**4. Mental health**

#### **4.1 Depression**

In the above a relation has been described between neuroticism and vegetarianism. It is also known that people with high neuroticism scores are more vulnerable to developing depression [32].

Depression is a mental state which is often associated with neuroticism. As mentioned above a vegetarian lifestyle is often associated with neuroticism. Therefore, it is assumed that a relation between depression and a vegetarian diet exists. Some studies show that in western culture a vegetarian diet is associated with a higher risk of depression [33]. In a longitudinal study among 9.668 male partners of pregnant women, vegetarians (3.6% of the sample) had higher depression scores on selfreports [34].

In a Chinese study of the elderly, the use of a vegetarian diet posed a higher risk for depressive symptoms, especially in men [35]. In a systematic literature review, including 18 studies with a total of 160.257 participants, 11 out of 18 studies showed that plant-based diets were associated with poorer mental health, 3 out of 18 studies showed better mental health, 4 out of 18 studies were equivocal. The higher-quality studies showed that people avoiding meat consumption ran a higher risk of depression/anxiety and/or self-harm behaviours. Despite differences in methodology and quality of the studies, the authors conclude that ending meat consumption is not a good strategy to promote psychological health [36]. In another recent systematic review and meta-analysis, including 13 studies with 17.809 individuals, it was found that vegetarians/vegans are at a higher risk of developing depressions [37].

In Seasonal Affective Disorder –winter type (SAD), an association between vegetarianism and SAD was found.

In an SAD outpatient clinic, the number of participants following a vegetarian diet was significantly higher than in the general population, and in a large group of vegetarians from Finland (from the Finnish national FINRISK 2012 study) the number of people with SAD was higher compared to omnivores [38].

Other studies arrive to different conclusions. In a study of diabetic patients in Iran, a plant-based diet seems to protect against developing depression, anxiety and stress, and these patients were better sleepers compared to meat eaters [39]. In a study of 15-year olds in four developing countries (India, Vietnam, Peru and

**23**

**4.2 Anxiety**

the benefits of the treatment [50].

*Vegetarian or Vegan Diet: Stimulating or at Risk to Mental Health?*

found between vegetarian, vegans and omnivores [41].

Ethiopia) no association was found between a vegetarian diet and emotional symptoms [40]. In a study of endurance runners, no differences in mental health were

In yet another study, the authors concluded that healthy dietary patterns do matter. The authors did not just compare plant-based diets versus diets containing meat. A healthy dietary pattern containing among other things fruits, whole grain, fish, olive oil, low-fat dairy and a low intake of animal food was compared to an unhealthy dietary pattern containing processed foods, red meats, refined grains, high-fat dairy products, sweets and a low intake of fruits and vegetables. The unhealthy diet was associated with an increased risk of depression [42]. Cultural beliefs and economic circumstances may also play a role. In a large-scale multinational cross-sectional study in four different countries it was found eating a vegetarian diet was not positively or negatively associated with mental health in the US, Germany and Russia, while in China vegetarians did run a higher risk of developing

If a relation between food and depression exists, the question arises what ingredients improve depressed mood, and more importantly what ingredients can help prevent or recover from depression. In a literature study, LaChance and Ramsey [44] found 12 antidepressant nutrients (folate, iron, long-chain omega-3 fatty acids (EPA and DHA), magnesium, potassium, selenium, thiamine, vitamin A, vitamin B6, vitamin B12, vitamin C, and zinc) which are found in plant foods like leafy greens, peppers and cruciferous vegetables, and sea-foods like mussels and oysters. These findings could lead to a ranking system of nutrients which can be used as a treatment opportunity for people with mental health issues. Another study presents some evidence for ranking plant-based food. In adolescents, regular, daily, diet of green and yellow vegetables was associated with a lower risk of depression compared to those who never ate these vegetables or only 1–2 times a week [45]. In a large cohort study (90.380 subjects) it was found that every exclusion of a food group (not exclusively animal products) from a diet was associated with the risk of developing depressive symptoms. As more food groups (meat, poultry, fish, eggs, milk and other dairy products, vegetables, legumes and/or grains) were excluded the more the risk of depression increased [46]. In addition to this, it is worth mentioning that it is still a matter of debate whether a vegetarian/vegan diet poses a risk to brain development even if supplements are added like iron, zinc and vitamin B12 [47, 48]. Some authors argue in favour of eating whole foods, not nutrients and emphasize the need for more holistic approaches in nutrition to preserve health, animal welfare, and the planet [49]. A 12-week intervention of plant-based diet, exercise, mindfulness, lifestyle and behaviour modification showed good results in the treatment of depression and anxiety, results which after 6 months still existed in most participants. In this study, it was impossible to distinguish between the different factors of the intervention, so it is unclear what the contribution of diet was to

A study of first year university students in the US found that vegetarians had

Although there is some evidence that a plant-based diet has some negative associations with mental health, there are also some studies contradicting these results. An international online survey recruited participants via diet-related social networks. Participants were divided into three group: vegans, vegetarians and omnivores. Vegans scored lower than omnivores on mood items, and male participants scored lower on anxiety scores compared to omnivores. Stress scores

higher perceived stress levels compared to non-vegetarians [51].

*DOI: http://dx.doi.org/10.5772/intechopen.94371*

depression [43].

#### *Vegetarian or Vegan Diet: Stimulating or at Risk to Mental Health? DOI: http://dx.doi.org/10.5772/intechopen.94371*

*Veganism - a Fashion Trend or Food as a Medicine*

peared when corrected for gender [29].

higher quality of life [31].

to developing depression [32].

vegetarianism and SAD was found.

**4. Mental health**

**4.1 Depression**

reports [34].

vores, and flexitarians scored somewhere in between [30].

personality traits, or found different results altogether.

omnivores scored higher on these traits, but that these effects weakened or disap-

In a small study using another method (the implicit association test) it was found that a positive attitude to plant-based diets was related to a more emphatic sensitivity towards humans and animals and also to a positive attitude towards healthy and natural products. There was a trend suggesting that vegetarians have a higher capacity to experience compassion for others who have negative experiences as compared to omnivores. Vegetarians showed a stronger association than omni-

It should also be mentioned that there are studies that failed to find significant differences between vegans/vegetarians and omnivores with respect to the Big-Five

An example is an online survey in which it was found that vegans were less neurotic than lacto-ovo vegetarians, more open and had more compatible personality traits, were more universalistic, empathic, and ethically oriented, and had a slightly

In the above a relation has been described between neuroticism and vegetarianism. It is also known that people with high neuroticism scores are more vulnerable

Depression is a mental state which is often associated with neuroticism. As mentioned above a vegetarian lifestyle is often associated with neuroticism. Therefore, it is assumed that a relation between depression and a vegetarian diet exists. Some studies show that in western culture a vegetarian diet is associated with a higher risk of depression [33]. In a longitudinal study among 9.668 male partners of pregnant women, vegetarians (3.6% of the sample) had higher depression scores on self-

In a Chinese study of the elderly, the use of a vegetarian diet posed a higher risk for depressive symptoms, especially in men [35]. In a systematic literature review, including 18 studies with a total of 160.257 participants, 11 out of 18 studies showed that plant-based diets were associated with poorer mental health, 3 out of 18 studies showed better mental health, 4 out of 18 studies were equivocal. The higher-quality studies showed that people avoiding meat consumption ran a higher risk of depression/anxiety and/or self-harm behaviours. Despite differences in methodology and quality of the studies, the authors conclude that ending meat consumption is not a good strategy to promote psychological health [36]. In another recent systematic review and meta-analysis, including 13 studies with 17.809 individuals, it was found

that vegetarians/vegans are at a higher risk of developing depressions [37].

number of people with SAD was higher compared to omnivores [38].

In Seasonal Affective Disorder –winter type (SAD), an association between

In an SAD outpatient clinic, the number of participants following a vegetarian diet was significantly higher than in the general population, and in a large group of vegetarians from Finland (from the Finnish national FINRISK 2012 study) the

Other studies arrive to different conclusions. In a study of diabetic patients in Iran, a plant-based diet seems to protect against developing depression, anxiety and stress, and these patients were better sleepers compared to meat eaters [39]. In a study of 15-year olds in four developing countries (India, Vietnam, Peru and

**22**

Ethiopia) no association was found between a vegetarian diet and emotional symptoms [40]. In a study of endurance runners, no differences in mental health were found between vegetarian, vegans and omnivores [41].

In yet another study, the authors concluded that healthy dietary patterns do matter. The authors did not just compare plant-based diets versus diets containing meat. A healthy dietary pattern containing among other things fruits, whole grain, fish, olive oil, low-fat dairy and a low intake of animal food was compared to an unhealthy dietary pattern containing processed foods, red meats, refined grains, high-fat dairy products, sweets and a low intake of fruits and vegetables. The unhealthy diet was associated with an increased risk of depression [42]. Cultural beliefs and economic circumstances may also play a role. In a large-scale multinational cross-sectional study in four different countries it was found eating a vegetarian diet was not positively or negatively associated with mental health in the US, Germany and Russia, while in China vegetarians did run a higher risk of developing depression [43].

If a relation between food and depression exists, the question arises what ingredients improve depressed mood, and more importantly what ingredients can help prevent or recover from depression. In a literature study, LaChance and Ramsey [44] found 12 antidepressant nutrients (folate, iron, long-chain omega-3 fatty acids (EPA and DHA), magnesium, potassium, selenium, thiamine, vitamin A, vitamin B6, vitamin B12, vitamin C, and zinc) which are found in plant foods like leafy greens, peppers and cruciferous vegetables, and sea-foods like mussels and oysters. These findings could lead to a ranking system of nutrients which can be used as a treatment opportunity for people with mental health issues. Another study presents some evidence for ranking plant-based food. In adolescents, regular, daily, diet of green and yellow vegetables was associated with a lower risk of depression compared to those who never ate these vegetables or only 1–2 times a week [45]. In a large cohort study (90.380 subjects) it was found that every exclusion of a food group (not exclusively animal products) from a diet was associated with the risk of developing depressive symptoms. As more food groups (meat, poultry, fish, eggs, milk and other dairy products, vegetables, legumes and/or grains) were excluded the more the risk of depression increased [46]. In addition to this, it is worth mentioning that it is still a matter of debate whether a vegetarian/vegan diet poses a risk to brain development even if supplements are added like iron, zinc and vitamin B12 [47, 48]. Some authors argue in favour of eating whole foods, not nutrients and emphasize the need for more holistic approaches in nutrition to preserve health, animal welfare, and the planet [49]. A 12-week intervention of plant-based diet, exercise, mindfulness, lifestyle and behaviour modification showed good results in the treatment of depression and anxiety, results which after 6 months still existed in most participants. In this study, it was impossible to distinguish between the different factors of the intervention, so it is unclear what the contribution of diet was to the benefits of the treatment [50].

#### **4.2 Anxiety**

A study of first year university students in the US found that vegetarians had higher perceived stress levels compared to non-vegetarians [51].

Although there is some evidence that a plant-based diet has some negative associations with mental health, there are also some studies contradicting these results. An international online survey recruited participants via diet-related social networks. Participants were divided into three group: vegans, vegetarians and omnivores. Vegans scored lower than omnivores on mood items, and male participants scored lower on anxiety scores compared to omnivores. Stress scores were lower in vegan females only. The difference between these results and other studies may be due to of methodological differences and a possible selection bias [52]. In their meta-analysis Iguacel et al. [37] found that a vegetarian/vegan diet was related to lower anxiety scores. Because of the heterogeneous character of the studies included, the authors made some sub-group analyses. In one of these subgroup analyses of anxiety it was emerged that mainly younger participants (under 26) ran a higher risk of developing anxiety. This last was a finding from the higher quality studies only.

### **4.3 Eating disorders**

People following a vegetarian or vegan diet are very conscious of their eating habits, and so are patients with eating disorders.

In a representative German survey (n = 2.449), participants were asked if they were vegetarian/vegan (5.4%) or omnivores and then filled out the Eating Disorder Examination Questionnaire (EDE-Q8). Vegetarians/vegans scored statistically significantly higher on the EDE-Q8 [53].

A study comparing subjects without eating disorders, with a non-clinical eating disorder and with a clinical eating disorder found that the group with the most severe eating disorders contained the highest number of vegetarians/vegans [54]. A comparison between vegetarians and omnivores yielded an association between following a vegetarian diet and orthorexia (unhealthy obsession with healthy eating), while omnivores often had more cognitive restraint as well as a higher body mass index [55].

Semi-vegetarians have been defined as vegetarians who only rarely eat meat. In a study looking for associations between diets with orthorexic tendencies and depression, semi-vegetarians with strong orthorexic tendencies show more depressive symptoms than omnivores and vegetarians. The authors speculate that semivegetarians with orthorexic tendencies have high or pathological health-related motives to become vegetarians and have failed to do so, which can be depressogenic because of the dissonance between their conception of good food and their actual behaviour [56].

### **4.4 Other disorders**

In a case study describing a 47-year-old female patient with a five-year history of psychosis, a serious vitamin B12 deficiency was found. Vitamin B12 in food is present in meat, fish, dairy products, and eggs. The patient had been following a strict vegan diet for seven years, and after administration of vitamin B12 the complaints disappeared. The authors point out that professionals should be aware of veganism as a cause of vitamin B12 deficiency and hence psychiatric complaints [57]. A vitamin B12 deficiency can lead to various mental disorders, such as depression, bipolar disorders, psychosis, and dementia [58]. It was found that, compared to omnivores, vegetarians often have vitamin B12 shortage and therefore are vulnerable to developing neuropsychiatric and neurological problems [59].

A cross-sectional survey in China of young children (3–6 year) showed a relation between dietary patterns and attention-deficit/hyperactivity disorder (ADHD). Unhealthy dietary patterns with processed foods and snacks were positively associated with ADHD complaints, and the more vegetarian food patterns negatively [60]. Unhealthy diet patterns may lead to a poor biochemistry status affecting ADHD behaviour. If this is the case, mental health professionals should be aware of this, in order to improve the ADHD symptomatology. No causal relationship between diet and ADHD symptoms is shown, but food preference patterns

**25**

*Vegetarian or Vegan Diet: Stimulating or at Risk to Mental Health?*

can be a consequence of ADHD behaviour [61]. Since people suffering from ADHD symptoms regularly have nutritional and vitamin deficiencies, nutritional assessments to detect potential deficits or allergies should be performed at the start of a treatment. Scientific evidence of using diet as a treatment of autism, as sometimes claimed, is weak and poor. A vegetarian diet does not lead to nutritional threats as it

In a *comprehensive* review of the literature on randomized clinical trials some evidence was found that vegetarian diets prevent or delay cognitive decline in

In the literature there is a growing number of papers mentioning a negative relation between mental health and a vegan/vegetarian diet; this particularly holds for a relation between vegan/vegetarian diet and depression. In most studies, it is unclear if a plant-based diet leads to depression or other mental problems, or if people with mental issues choose a vegan/vegetarian diet more often. It is possible that people who are vulnerable for depression, anxiety and stress are more concerned about their own well-being, health and the fate of the Earth, and therefore

Although many relations have been found, it is good to emphasize that a large number of these studies suffer from methodological limitations. Most are cohort studies or cross-sectional studies, in which no causal relation can established. In a recent study, data of several studies were pooled and no association was found between vegetarian diet and depression (pooled data of 10 studies) and also no association between vegetarian diet and anxiety either (pooled data of 4 studies) [65]. Another recent study shows that reviewing methodology matters. In this study, where the conclusions of different reviews about the effects of diets on depression are compared, it is shown that *narrative* reviews come to stronger conclusions than *systematic* reviews with and without meta-analyses [66]. Authors' selection bias and differences in a priori assumptions for the meta-analyses may also play a role. For

Some reasons (other than ethical, religious, animal welfare or health) for the growing popularity of plant-based diets are climate change and high greenhouse gas (GHG) emissions. Meat consumption is a major contributor to global warming. Looking for plant-based alternatives as a resource of proteins instead of animal foods is claimed as an attractive alternative. This can lead to a reduction in the use of arable land, nitrogen fertilizer, water and GHG emissions and therefore can lead to improved public health [67]. But there are other factors than proteins in food that are important for physical, and mental health (as discussed in this chapter).

Some plant foods (citrus fruit, grapes, berries, cocoa, nuts, green tea and coffee) improve specific cognitive domains, most notably frontal executive functions [63]. A different conclusion can be reached by using a different review methodology when examining the literature. In a *systematic* review of the literature on the effects of plant-based diets on body and brain, no evidence was found for the putative effects of a plant-based diet. No causal relation was seen between the use of a plantbased diet and effects on cognitive functions, mental and neurological functioning,

*DOI: http://dx.doi.org/10.5772/intechopen.94371*

**5. Neurologic/neuropsychologic aspects**

nor for any underlying mechanism [64].

make a more conscious choice of diet.

more robust conclusions clinical RCT trials are needed.

includes eggs and milk [62].

elderly adults.

**6. Conclusion**

can be a consequence of ADHD behaviour [61]. Since people suffering from ADHD symptoms regularly have nutritional and vitamin deficiencies, nutritional assessments to detect potential deficits or allergies should be performed at the start of a treatment. Scientific evidence of using diet as a treatment of autism, as sometimes claimed, is weak and poor. A vegetarian diet does not lead to nutritional threats as it includes eggs and milk [62].


**4. Results**

Results from DMA tests were shown as storage and loss moduli changes (Figure 3). The glass transition temperature determined from loss modulus changes along the temperature growth was equal to 107.5 ◦C (Figure 3).

**Figure 3.** Results from DMA test.

The results from tensile strength tests were summarized (Table 1). The medium values of elasticity modulus were in the range from 43.3 to 44.6 MPa, while tensile strength medium values were 930.5 to 1073.1 MPa.

**Table 1.** Summary of the results—BFRP bars in tension.

1 determined only for one specimen. 2 mean value calculated on specimens tested from two directions.

Two out of the three Ø12 specimens with caps mounted with epoxy resin did not fail during the test as a result as achieving stresses equal to tensile strength, but the FRP bars with hardened epoxy resin started to slide out of the steel caps. Therefore, maximum strength values should not be considered as tensile strength in that case, and were excluded from the analysis. Nevertheless, elasticity moduli were calculated for these specimens. Figure 4 shows the typical mode of failure for the analysed specimens.

**Figure 4.** Specimen after failure in tension.

The results of the compressive tests at room temperature are summarized in Table 2, while Figure 5 shows the typical form of failure in compression. The medium values of compressive strength were in the range of 441.2 to 456.0 MPa, and medium values of elasticity modulus were in the range of 31.0 to 38.4 MPa.

1 mean value calculated on specimens tested from two directions.

**Figure 5.** Specimen after failure in compression.

Compressive strength along with temperature at the surface of the specimen at failure time, at compressive strength tests at elevated temperatures (100 ◦C and 200 ◦C), are summarized in Table 3. Additionally, the results for four reference specimens tested without heating on the same day are included in this table. The strength retention ratio calculated for the medium temperature at failure equal to 97.3 ◦C was 24%, and for 191.0 ◦C, it was 8%.

**Table 3.** Compressive strength tests during heating results.

### **5. Discussion**

Tensile and compressive strength for BFRP bars may strongly vary depending on the type of used matrix, fibres, and volumetric proportions between matrix and fibres.

Basing on a comparison of the results from available experimental studies on mechanical properties of the BFRP bars ([2,3,12–16]—Table 4) the differences between tensile strength may vary from under 600 to even over 1500 MPa, which is a very wide range. In most cases, the tensile strength of the BFRP bars was higher than the typical value of tensile strength for steel reinforcement (about 500–600 MPa). However, no yielding occurs for non-metallic bars. As a result, rupture failure modes were noted in most cases in tension, which may result in a low safe reserve for design purposes.

In terms of tensile strength, the results from this study are similar to the works of Protchenko et al. [13], Urbanski et al. [14] and Włodarczyk and Trofimczuk [16].

Regarding compressive strength of the BFRP bars, there are few data available in the literature concerning this parameter. The reason for that may be the fact that reinforcement bars are typically submitted to tension during their lifecycle in most concrete structures. However, it is worth considering during designing that the compressive strength of the bars can be significantly lower than their tensile strength, and also lower than compressive strength of most of steel reinforcement bars (typically around 500–600 MPa). Moreover, similar results for compressive strength were noted within this study and by Thiyagarajan et al. [3] (about 450–500 MPa).

Elasticity modulus in tension measured within this study was equal to about 45 GPa, which is similar to other studies (38.34–52.0), apart from the Elgabbas et al. studies [2,15], in which the bars had a significantly higher stiffness (59.5–90.4 GPa). Even the highest value of elasticity modulus for BFRP bars amongst the available analysed literature (90.4 GPa) is much lower than typical values for reinforcement steel (about 210 GPa). This may lead to excessive deflections and crack propagation in bent concrete elements with non-metallic reinforcement.

Additionally, this study aimed to experimentally determine elasticity moduli at compression, which were 15–30% lower than the values measured in tension.

Further research will concern the examination of tensile strength at elevated and high temperatures in comparison to the available literature data [17–20]. The results from the current study will also be used for numerical modelling purposes regarding axially compressed concrete columns with BFRP reinforcement bars at room and high temperatures.

**Table 4.** Mechanical properties of the BFRP bars—comparison.


**2. The privatisation of the water supply and the institutional management of the process**

The section presents various issues on water privatisation in particular and water sector reforms in general as expressed in international literature. It presents cases of small scale water service providers as an alternative water service provision mechanism whose success could either be impeded or enhanced by the methods of the privatization adopted by a particular country.


**3.4 Time factor in PORT**

Two aspects of timing with regards to radiotherapy has been shown to be important for eventual outcomes in head and neck cancer management – overall treatment duration of radiotherapy as well as total time of both surgery and radiotherapy in CMT. Prolongation of both these indices seems to negatively impact the outcomes. Ang et al. conducted a multi-institutional study including 288 patients and found that in high-risk H&N cancers, there was a trend towards higher LRC and survival rates when PORT was delivered in 5 rather than 7 weeks [31]. Also, a

prolonged interval between surgery and PORT of >6 weeks or a total duration of surgery and PORT of >13 weeks significantly impacted outcomes negatively.

Huang et al. in their meta-analysis involving 46 studies dealing with this aspect found that in the combined analysis the rates of local recurrences were significantly higher among patients who received PORT more than 6 weeks after surgery (OR = 2.89; 95% CI) [32].

Fast tumour cell repopulation has been postulated as the reason behind why prolonging overall treatment time (OTT) can negatively impact local control and survival in cancers. González Ferreira et al. in their review of literature found prolongation of OTT resulted in an average loss of LRC ranging from 1 to 1.2%per day to 12–14% per day, requiring an average increase of 0.6–0.8Gy/day to compensate for it [33]. Also, they postulated that the lag period for the accelerated repopulation to be initiated was between 21 and 28 days.

Graboyes et al. conducted an institutional review to study this aspect and found that starting PORT > 6 weeks post-surgery resulted in decreased OS rates in both multivariate and propensity score-matched subsets [34]. They also found that increasing delay beyond 6 weeks resulted in small, progressive survival decrements [aHR 1.09, 1.10, 1.12 for 7–8 wks, 8–10 wks and >10wks respectively].

Zumer et al. did a retrospective analysis to identify the relationship between time before treatment intervention and tumour growth kinetics on treatment outcomes in those undergoing definitive radiotherapy with or without chemotherapy in 273 head and neck cancer patients [35]. There was no significant association between loco-regional control or survival indices and time to treatment intervention. They also found that the median tumour volume relative increase rate & tumour volume doubling time was 3.2%/day and 19 days respectively, but both had no impact on outcomes.

#### **3.5 Dose & volumes considerations for radiation in oral cancers**

As a principle in radiotherapy, at least for oral cavity squamous cell carcinomas, the dose needs to be delivered in the desired fractionated regimen without unnecessary interruptions and in the shortest time possible with no reduction in dose below that what is tolerated by late responding normal tissue.

This means that the total dose is important to prevent local recurrences and the factors that need to be kept in mind are [36].

Radiotherapy in oral cavity tumours is associated with lot of acute as well as chronic toxicities which will be dealt separately. In order to minimise this, there are several steps taken and one of them is the use of highly conformal Intensity modulated radiotherapy (IMRT), and there is lot of data to support its use in head and neck cancers. Before starting radiation therapy all patients undergo a detailed examination by a dental surgeon and this is known as dental prophylaxis. The dental surgeon will assess the area of treatment and also estimate the dose that would probably be delivered to the surrounding bony structures as well as ascertain the status of the teeth and score it as per DMF (Decayed, Missing, Filled) index.

### *Radiotherapy in Oral Cancers: Current Perspective and Future Directions DOI: http://dx.doi.org/10.5772/intechopen.99557*

Based on this, treatment is advised and appropriately followed. By doing this exercise, the chances of osteoradionecrosis & soft tissue related long-term toxicities can be reduced or even eliminated. IMRT involves simulation and planning for which the most basic step is immobilisation by thermoplastic facemask attached to a base plate indexed to the treatment table. After the planning CT scan is done the volumes are outlined on them as per the guidelines [37].


**Section 3 Computer Engineering 139**

Chapter 7 **Training Images-Based Stochastic Simulation on Many-Core Architectures 141** Tao Huang and Detang Lu

#### **Section 4 Materials and Metallurgical Engineering 159**

	- **Section 5 Geotechnical Civil Engineering 243**


Clay Minerals in Nature Their Characterization, Modification and Application

*Edited by Marta Valaškova and Gražyna Simha Martynková*

**CLAY MINERALS**

**APPLICATION**

Edited by **Marta Valášková**

and **Gražyna Simha Martynková**

**IN NATURE – THEIR**

**CHARACTERIZATION,**

**MODIFICATION AND**


2.3.5. Control Algorithm

In this section, we focus on the tuning control as implemented in the system-level model of Figure 2. A control algorithm, as visualized in Figure 12, maintains maximum voltage output even under varying excitation frequency. We consider this as a realistic use case. The time variable and DC voltage output are used as inputs for the control algorithm. The control scheme analyzes the voltage levels at a given frequency and selects one of the two tuning mechanisms.

**Figure 12.** Tuning control algorithm scheme based on maximum-voltage tracking.

In order to demonstrate the self-adaption of our harvester, we excite the structure with a stepwise frequency-varying harmonic excitation, as illustrated in Figure 13. The results demonstrate that the system is able to choose the adequate tuning mechanism. This choice is based on the current voltage level. The maximum voltage is achieved within 15 s. In contrast to our previous work [33], where we implemented an adaptive step size, here the tuning scheme employs a constant step size. This results in less tuning steps, which improve the energy efficiency of the tuning mechanism.

**Figure 13.** A control algorithm, which is based on maximum-voltage tracking, chooses the most effective tuning actuator.


*Article* **The August 2018 Geomagnetic Storm Observed by the High-Energy Particle Detector on Board the CSES-01 Satellite**

**Francesco Palma 1,\*,†, Alessandro Sotgiu 1,2, Alexandra Parmentier 1, Matteo Martucci 1,2, Mirko Piersanti 3, Simona Bartocci 1, Roberto Battiston 4,5, William Jerome Burger 5,6, Donatella Campana 7, Luca Carfora 1,2, Guido Castellini 8, Livio Conti 1,9, Andrea Contin 10,11, Giulia D'Angelo 3, Cinzia De Donato 1, Cristian De Santis 1, Francesco Maria Follega 4,5, Roberto Iuppa 4,5, Ignazio Lazzizzera 4,5, Nadir Marcelli 1,2, Giuseppe Masciantonio 1, Matteo Mergé 1,†, Alberto Oliva 11, Giuseppe Osteria 7, Federico Palmonari 10,11, Beatrice Panico 7, Francesco Perfetto 7, Piergiorgio Picozza 1,2, Michele Pozzato 11, Ester Ricci 4,5, Marco Ricci 12, Sergio Bruno Ricciarini 8, Zouleikha Sahnoun 11, Valentina Scotti 7,13, Roberta Sparvoli 1,2, Vincenzo Vitale 1, Simona Zoffoli 14 and Paolo Zuccon 4,5**

**Abstract:** On 25 August 2018, a G3-class geomagnetic storm reached the Earth's magnetosphere, causing a transient rearrangement of the charged particle environment around the planet, which was detected by the High-Energy Particle Detector (HEPD) on board the China Seismo-Electromagnetic Satellite (CSES-01). We found that the count rates of electrons in the MeV range were characterized by a depletion during the storm's main phase and a clear enhancement during the recovery caused by large substorm activity, with the key role played by auroral processes mapped into the outer belt. A post-storm rate increase was localized at L-shells immediately above ∼3 and mostly driven by non-adiabatic local acceleration caused by possible resonant interaction with low-frequency magnetospheric waves.

**Citation:** Palma, F.; Sotgiu, A.; Parmentier, A.; Martucci, M.; Piersanti, M.; Bartocci, S.; Battiston, R.; Burger, W.J.; Campana, D.; Carfora, L.; et al. The August 2018 Geomagnetic Storm Observed by the High-Energy Particle Detector on Board the CSES-01 Satellite. *Appl. Sci.* **2021**, *11*, 5680. https://doi.org/ 10.3390/app11125680

Academic Editor: Kambiz Vafai

Received: 20 May 2021 Accepted: 16 June 2021 Published: 19 June 2021

**Publisher's Note:** MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

**Copyright:** © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

**Keywords:** space weather; geomagnetic storms; LEO satellites; particle detectors

#### **1. Introduction**

Magnetic storms represent major signatures of variability in the Sun-Earth interaction. Such events appear as magnetic disturbances caused by bursts of radiation and charged particles emitted from the Sun in the form of coronal mass ejections (CMEs), solar flares, co-rotating interaction regions (CIRs), etc. [1,2]. These nonlinear and multiscale processes involve a vast set of plasma regions in the mutually interacting magnetosphere and ionosphere.

The terrestrial magnetosphere is under the permanent action of the solar wind. An increase in the solar wind dynamic pressure and a southward direction of the interplanetary magnetic field (IMF) are considered among the fundamental factors in magnetic storm development [3,4]. Under the solar wind driver, global changes occur in the magnetosphere following two principal dynamic triggers: magnetic reconnection at the dayside magnetopause [5] and viscous-like interactions causing magnetospheric convection [6]. One major consequence is the change in the fluxes of charged particles that constitute the magnetospheric ring current [7]. In cascade, the magnetosphere, which is mapped to the upper ionosphere through a system of field-aligned currents, can exchange momentum, energy, and particles with the latter by means of a variety of interactions [8,9]. For example, the transport of plasma between the plasmasphere and ionosphere is severely impacted by altered geomagnetic activity, leading to convection-driven erosion and refilling of the plasmasphere [10] or depletion due to reduced upward flux from the perturbed ionosphere [11].

Discerning physical phenomena that mark the solar-terrestrial environment is not the sole goal of the investigation of storm phenomena, since currently, geomagnetic storms and substorms can severely impact infrastructures at the ground level and in space, also posing a hazard to human health [12–17].

On 25 August 2018, the China Seismo-Electromagnetic Satellite (CSES-01) encountered the first strong magnetic storm since its launch on 2 February 2018. In this paper, after a sketch of the CSES-01 mission and the High-Energy Particle Detector (HEPD) in Section 2, a description of the major solar and geomagnetic characteristics of the storm is reported (Section 3). The magnetospheric disturbance was strong enough to trigger a response in the HEPD instrument; this is presented on the basis of HEPD trigger rate variations observed in the MeV energy range as a function of time and the McIlwain L-shell parameter (Section 4). Observations of this storm in a lower energy interval—from other particle detectors on board CSES-01—were previously presented in [18]. We discuss our results and draw our conclusions in Sections 5 and 6, respectively.

#### **2. Data and Methods**

#### *2.1. CSES-01 Mission and HEPD Detector*

The CSES-01 [19] is the first item of a multi-satellite constellation under construction by several missions scheduled for the next few years. The satellite was designed for the observation of variations in particle fluxes, plasma parameters, and the electromagnetic field and waves, induced by both natural and anthropogenic sources in the near-Earth space. One major goal of this Chinese-Italian space mission is to investigate possible correlations between the above-mentioned perturbations and the occurrence of high-magnitude earthquakes. Other fundamental targets are the study of space weather phenomena [18,20] and cosmic ray propagation [21].

The CSES-01 relies on the Chinese three-axis stabilized CAST2000 platform, and it is flying in a Sun-synchronous polar orbit at a ∼507 km altitude with a 97◦ inclination and a five-day revisit time. Nine scientific payloads are present on board the satellite [22–30], among which is the HEPD particle detector, which was designed and built by the Ital-

ian Limadou Collaboration. A schematic representation of the apparatus is reported in Figure 1. The HEPD is made up of a silicon tracking system; a trigger system that includes one plastic scintillator layer segmented into six paddles; a range calorimeter comprising a tower of 16 plastic scintillator planes, a matrix of 3 × 3 LYSO (lutetium–yttrium oxyorthosilicate) scintillator crystals, and an anti-coincidence (VETO) system equipped with 5 plastic scintillator planes, out of which 4 are placed at the lateral sides of the apparatus and 1 at the bottom (see [30,31]).

Thanks to this set of subdetectors, the HEPD is optimized to detect electrons in the energy range between 3 and 100 MeV and protons between 30 and 250 MeV, as well as light nuclei. In addition, the apparatus can detect different particle populations (solar, trapped, galactic, etc.) according to the satellite position (defined by the McIlwain L-shell parameter) and detected energy.

**Figure 1.** Schematic of the HEPD detector. All mechanical structures (as well as the lateral VETO plane located in the front) have been removed from the figure for visualization purposes.

The transmission of a dedicated command allows setting one of the eight predefined trigger mask configurations [32], which are the result of different logic combinations of counters from the various subdetectors. Hence, the different trigger masks define the aperture and the energy acceptance of the instrument. The trigger condition, labeled as T, corresponds to an above-threshold signal only in the trigger plane, and it is associated with the lowest energy threshold. By requiring a deeper penetration of the particle inside the detector (i.e., using the trigger plane counters and a set of tower planes in "AND" configuration, such as T & P1, T & P1 & P2, and so on), the geometric factor of the HEPD decreases, and consequently, the energy threshold for triggering increases. In July 2018 (late commissioning phase), the HEPD was configured with a trigger condition, labeled as T & P1 & P2, which corresponds to event acquisition and processing only when the released signals in the trigger plane and the first two calorimeter planes (P1, P2) are above predefined thresholds. However, for each of the predefined masks, even when not selected for the online acquisition, a rate meter independently provides the corresponding trigger

counting rate (1 s resolution). In this paper, we used the rate meters of three trigger masks (T, T & P1, and T & P1 & P2), corresponding to the integral number of particles per second above different energy thresholds.

Due to adjustments in attitude and additional scheduled maneuvers, the CSES-01 payloads are usually switched off at latitudes below −65◦ and above +65◦. However, the HEPD can benefit from its large field of view (±60◦) and geometrical acceptance to collect particles at large L-shells, though for a short time per day. Figure 2 shows the Monte Carlo-based geometrical factor of the HEPD for electrons in three different trigger configurations. In the current one (T & P1 & P2), the geometrical factor reaches a plateau value of ∼500 cm2sr at energies larger than ∼30 MeV.

**Figure 2.** The HEPD geometrical factor for electrons, as estimated from Monte Carlo simulations, as a function of kinetic energy and trigger configuration.

#### *2.2. NOAA19/POES Satellite*

NOAA19 is the youngest element in the constellation of the National Oceanic and Atmospheric Administration (NOAA) Polar Orbiting Environmental Satellites (POES), moving along a Sun-synchronous low-Earth orbit (revisit time: 102 min; inclination: 98.7◦) at an altitude of ∼850 km, and currently serving as the Prime Service Mission.

The onboard SEM-2 package mounts the Medium Energy Proton and Electron Detector (MEPED) [33], also including two couples of 30◦-wide telescopes, of which two are approximately zenith-pointing (MEPED-0◦) and two have an azimuthal orientation (MEPED-90◦). The electron telescope pair operates in the range from 40 to 2500 keV, over four integral energy channels (E1: > 40 keV; E2: > 130 keV; E3: > 287 keV; E4: > 612 keV).

The Sub-MeV fluxes used in this study were from the MEPED-90◦ electron telescope in the E2 channel, which represents the best compromise in terms of detection efficiency over the available energy range [34] vs. proton contamination [35].

#### *2.3. DMSP Satellite*

The auroral observations used in this study were from the Defense Meteorological Satellite Program (DMSP), consisting of a group of polar, Sun-synchronous satellites flying at ∼850 km with a period of ∼100 minutes [36]. The DMSP mission focuses on the observation of the near-Earth space plasma environment. In particular, we used the Special Sensor Ultraviolet Spectrographic Imager (SSUSI) instrument on board the DMSP, which is designed to measure far-ultraviolet emissions via imaging spectrograph (SIS) mapping through 5 spectral bins: 121.6 nm (*H I* Lyman *α*), 130.4 nm (*OI*), 135.6 nm (*OI*), 140–160 nm (*N*2 LBHS) and 160-180 nm (*N*2 LBHL) [37]. The image resolution is 16 × 156 pixel, while the time resolution (i.e., time to fly above the polar region and acquire an image) is between 20 and 30 min [37].

#### *2.4. RBSP Satellites*

The dual-spacecraft Radiation Belt Storm Probes (RBSPs) move along highly elliptical orbits (extending from 1.2 to 5.8 *RE*) at an inclination of 10◦, thus offering a non-ionospheric point of view due to direct penetration of the radiation belts.

The Relativistic Electron-Proton Telescope (REPT) on board the satellites of the RBSP class measures electrons in differential bins in the energy range ∼1–20 MeV with high detection efficiency above 5 MeV. A background partly due to galactic cosmic rays primarily afflicts the REPT measurements in the highest electron channels [38].

#### *2.5. Magnetopause and Plasmapause Position Models*

The magnetopause position was obtained by means of the Tsyganenko [39,40] T01 magnetospheric field model. T01 is a semi-empirical model in which the total magnetospheric field of external origin comes from the sum of the Chapman-Ferraro current and contributions from cross-tail, ring, and field-aligned currents. All these contributions are calculated taking into account the solar wind (SW) dynamic pressure, the interplanetary magnetic field (IMF) configuration, and the Dst index. For the present analysis, we used the SW and IMF observations stored in the OMNI CDAWeb repository.

The plasmapause location was assessed using the Liu and Liu [41] model, which is based on the experimental THEMIS-D satellite plasmapause crossing database. The model is based on the following equation:

$$
\phi = 2\pi (MLT/24)\_{\prime\prime}
$$

$$\begin{array}{rcl} \mathbb{E}\_{pp} = & a\mathbf{1} \cdot \left[ \mathbf{1} + a\_{MLT} \cos(\phi - 2\pi a\_{\text{pli}}/24) \right] \cdot \log\_{10} |D \text{st}\_{index}| + \\ & + b\mathbf{1} \cdot \left[ \mathbf{1} + b\_{MLT} \cos(\phi - 2\pi b\_{\text{pli}}/24) \right] .\end{array}$$

where MLT is the magnetic local time. The parameters used in the calculation of Ł*pp* are reported in Table 1.

**Table 1.** Parameters used to estimate the plasmapause location.

#### **3. The August 2018 Geomagnetic Storm**

On 20 August 2018, a large-scale filament gradually erupted from a quiet region of the Sun into an interplanetary CME (ICME) that affected the Earth's environment a few days later, starting on late 25 August 2018 [42] and giving rise to the third largest storm of Solar Cycle 24.

Figure 3 shows the SW parameters as retrieved by the ACE satellite (at the Lagrangian L1 point) from 23–31 August 2018. The magnetic cloud impinged the Earth's magnetosphere between 25 August at ∼12:15 UT and 26 August at ∼10:00 UT. Looking at Figure 3, we were able to determine the ICME boundaries [43] using the IMF behavior (Panel a) in conjunction with the SW temperature (Panel c) and the SW dynamic pressure (Panel d). Indeed, upon the ICME's arrival, the SW temperature decreased from ∼9 × 104 K to ∼1.5 × 104 K, while the IMF increased to 18 nT, lasting for approximately 12 h. At the same time, the IMF underwent a smooth rotation, leading to a prolonged (∼22 h) southward orientation (Panel b) at ≈14:30 UT on 25 August. Finally, the solar wind dynamic pressure fluctuated between ∼4 nPa and ∼10 nPa. A CIR followed on 26 August: the SW temperature increased from ∼ ×104 K to nearly 30 × 104 K around 12:20 UT, with the pressure increasing from ∼2 nPa to ∼8 nPa, as the solar wind stream was crossing a negative polarity high-speed stream (HSS) [42].

**Figure 3.** Solar wind parameters observed by the ACE spacecraft at L1: (**a**) IMF intensity; (**b**) IMF *Bz* component; (**c**) proton temperature; (**d**) dynamic pressure of the solar wind; (**e**) Sym-H index; (**f**) AE (black), AL (red), and AU (blue) indices. The SW parameters are expressed in the Geocentric Solar Magnetospheric (GSM) coordinate system.

To evaluate the consequences of the ICME impact on the Earth's environment, we used the Sym-H index (which mirrors the dynamics of the symmetric part of the ring current [44]) and the AE index (which indirectly measures the energy deposition rate in the polar ionosphere [45]). On 26 August, Sym-H (Figure 3e) showed a rapid decrease, reaching its minimum value (∼ −190 nT) at 07:57 UT. This structure mimics the behavior of the *Bz* component of the IMF, which shows a long-lasting (∼10 h) negative value starting at 16:52 UT of 25 August. This trend is clearly related to the southward IMF carried by the magnetic cloud [43]. As a consequence of this long interval of negative *Bz*, the SW plasma could flow inside the Earth's magnetosphere, possibly due to the occurrence of magnetic reconnection at the magnetopause between the geomagnetic field and the IMF [42].

The large bursts in the AE index (black line in Figure 3f) can be related to a sequence of fast relaxation events, possibly stemming from an activity in the near-Earth magnetotail regions in the form of a sequence of loading-unloading releases of energy [46,47]. Such processes give rise to a great amount of particle precipitation in the high-latitude region as confirmed by the behavior of the AL index (red line), which is excellently correlated with the negative turn of *Bz*. AL (and hence AE) peaks are directly related to the north-south flip of *Bz* between 11:00 UT and 21:00 UT on 26 August, induced by the arrival of the CIR.

#### **4. HEPD Response to the August 2018 Storm**

Figure 4 illustrates a comparison between the HEPD count rate maps before (20–23 August; upper panel) and after the impact of the storm (25–27 August; lower panel). In the top panel, the southern polar region presents a larger trigger rate than the northern one. This is due to the dipole tilt angle, which, in August, allowed the CSES-01 to explore higher geomagnetic latitudes in the Southern Hemisphere than in the Northern Hemisphere. In the bottom panel, an increase in the count rate is evident at both northern and southern latitudes—especially in the southern region—as a consequence of the storm's arrival. Both maps are related to trigger configuration T in Section 2, which requires an abovethreshold signal only in the trigger plane and allows detecting the lowest energetic electrons (>3 MeV). As concerns protons, their contribution to the trigger rate increase is negligible due to the absence of direct injection from solar energetic particles (SEPs) during this specific storm event [48]. For visualization purposes, we excluded the South Atlantic Anomaly (SAA) region, which is characterized by extremely high particle rates. For this purpose, we selected magnetic field values larger than 23,000 nT. For this analysis, we calculated magnetic field values by using the International Geomagnetic Reference Field (IGRF) series of mathematical models, in particular the IGRF-12 candidate [49].

The increased particle rate, during the storm time, is also visible as a function of the L-shell and time in Figure 5. The first three panels show the HEPD count rates for three different trigger configurations: from top to bottom, T, T & P1, and T & P1 & P2. The increase in the number of calorimeter planes used for trigger generation resulted in a higher energy threshold for electron detection (>3 MeV, >4.5 MeV, and >8 MeV, respectively), thus reducing the particle rate. For comparison, the time evolution of the Dst index is shown in the bottom panel of Figure 5. As can be inferred by a strong decrease of the Dst down to ∼−190 nT, the start of the storm's main phase was on late 25 August, exactly in coincidence with the increase of the HEPD particle rates.

**Figure 4.** Comparison between an HEPD trigger rate map before the occurrence of the geomagnetic storm, from 20–23 August (upper panel), and after the impact of the storm, from 25 August to 27 (lower panel). The maps are related to trigger configuration T, requiring an above-threshold signal just in the trigger plane and providing the lowest energy threshold for electron detection (>3 MeV). For visualization purposes, we excluded the South Atlantic Anomaly region, characterized by extremely high particle rates.

**Figure 5.** Top three panels: Trigger rates for three different HEPD configurations over the period August-September 2018; from top to bottom, T, T & P1, and T & P1 & P2. Adding more calorimeter planes to the trigger configuration results in increasing the energy threshold for electron detection (>3 MeV for T, >4.5 MeV for T & P1, and >8 MeV for T & P1 & P2). The proton contribution to the trigger rate increase is negligible due to the absence of direct injection from SEPs. The vertical white lines are due to a lack of data. Bottom panel: Time evolution of the Dst index.

#### **5. Discussion**

The hit of the ICME gives rise to a compression of the magnetosphere and a backward motion of the plasmasphere, as shown in Figure 6. Indeed, the magnetopause (black line), modeled using the T01 model [39,40] at the moment of the minimum value of the main phase of the geomagnetic storm (i.e., Dst minimum), steps back from ∼10*RE* before the storm down to ∼7.7*RE* (*RE* being the Earth's radius); while the plasmapause, evaluated by the model of Liu and Liu [41], moves from ∼5*RE* down to ∼3.8*RE*. On the other hand, the position of the inner boundary of the outer radiation belt (ORB) should reach *LORB* = 3.5, in accordance with the relation of Tverskaya [50] (|*SymH*|*max* = *c* · *L*−4 *ORB*, where *c* = 3 × 104 nT).

A depletion of the particle count rate (Figure 5) during the main phase of the storm is followed by a clear enhancement during recovery, which coincides with large substorm activity (>1000 nT) as measured by the AL index (red line in Figure 3f). The increase can be spotted at L-shells -3 for energies above 3 MeV (Figure 5, top panel) and, to a lesser extent, at L-shells -4 for energies above 4.5 MeV (Figure 5, second panel).

**Figure 6.** Magnetopause (black line) and plasmapause (red line) profiles as evaluated using the Tsyganenko T01 and the Liu (2014) models, respectively. The reference frame is the GSM. The SW parameters used in the T01 model are: *P* = 8.7 nPa; *By*,*IMF* = 4.5 nT; *Bz*,*IMF* = −16.8 nT; Dst = −174 nT. The Dst index value used in the plasmapause model is the same as in T01.

As a comparison, the >130 keV electron fluxes measured over the same period by the 90◦ Medium Energy Proton and Electron Detector (MEPED) on board the NOAA19 satellite are reported in Figure 7. The azimuthal telescopes of the MEPED class are affected by small >280 keV proton contamination even at large L-shells in disturbed periods (<0.6% at 4 < L < 7) [35].

The sub-MeV MEPED-90◦ observations appear fairly consistent with their MeV counterpart detected by the HEPD, yet reaching flux peaks two orders of magnitude larger than the count rates captured at higher energies. The arrival of the ICME triggered a clear slot-filling event that lasts several days after the impact, with flux enhancements reaching L-shells lower than those occupied by MeV electrons, in accordance with the apparent "barrier" revealed by the Van Allen Probes to significant inward transfer of ultrarelativistic electrons below L ∼2.5 [51].

**Figure 7.** Integral electron fluxes (>130 keV) measured by the MEPED-90◦ directional telescope on board the NOAA19 satellite over the period Aug-Sept 2018. As reported in [35], proton contamination remains modest in this class of azimuthal detectors even at large L-shells in disturbed periods (<0.6% at 4 < L < 7).

Prolonged and intense substorm activity during recovery (Figure 3f) shows that auroral processes play a non-negligible role in the analysis of particle acceleration in the ORB and that electrons can undergo a quick acceleration on typical timescales of auroral substorms. Taking into account that the auroral oval (AO) is mapped into the outer portion of the ring current (see [52] and the references therein) can help us better understand the connection between auroral processes and ORB dynamics. Indeed, Figure 4 shows a clear lowering of the AO region in concurrence with the storm (lower panel) with respect to the quiet reference conditions (upper panel). Such results are in agreement with ultraviolet (UV) observations by DMSP/SSUSI [37,53] for both hemispheres (Figure 8c,d). Indeed, UV images in the right column of Figure 8 display clear auroral precipitation at lower latitudes than during pre-storm conditions (left column) as a consequence of the high level of geomagnetic activity induced by south-oriented *Bz*,*IMF* (see Figure 3) and the expansion of the AO boundaries towards lower latitudes (red dashed lines in Figure 8).

**Figure 8.** The auroral ultraviolet images by the SSUSI instrument on board the DMSP satellite. Panel (**a**) refers to the quiet Northern Hemisphere observations; Panel (**b**) refers to the quiet Southern Hemisphere observations; Panel (**c**) refers to the stormy Northern Hemisphere observations; Panel (**d**) refers to the stormy Southern Hemisphere observations; the red dashed curves refer to the upper and lower boundaries of the auroral oval. The red curve refers to CSES-01's orbit. The selected reference is the Altitude Adjusted Corrected Geomagnetic (AACGM) coordinate system.

Peaks in the particle count rate during the recovery phase pinpoint a phenomenon of electron acceleration in the radiation belts, which could be ascribed to either adiabatic radial transport or nonadiabatic local heating by resonant interaction with very-low-frequency (VLF) waves [54]. Indeed, in order to make a discrimination between the two drivers, one can observe the radial phase space density (PSD) profiles of REPT electrons—directly monitored in the core of the belts—in the invariant (*μ*,*K*,*L*∗) space at fixed *μ* and *K*.

Radial diffusion moves (mostly 90◦ pitch angle, i.e., equatorially mirroring) electrons across different *L*∗ values while the *μ* and *K* invariants remain conserved, thus producing PSDs with a monotonic decrease from the outer source. Conversely, local acceleration makes PSDs increase over a limited *L*∗ range, with local peaks and negative radial gradients at higher *L*∗ values. Here, we set *K* at 0.1 *REG*1 2 under T04 field modeling, which addressed electrons with pitch angles generally greater than 45◦ and measured nearly continuously by the REPT instrument over a still broad range of *L*∗ [55]. On the other hand, electron energy corresponding to a particular *μ* changes with *L*∗, such that, fixing *μ* at 4500 *MeV G* , the range between ∼3 MeV and ∼7 MeV can be monitored.

Following the evolution of REPT PSDs from late 26 August to early 30 August (Figure 9), at higher *L*∗ values, peak structures with negative gradients were recovered, which, along the previous revelation of persistent chorus waves during the August 2018 event [56], calls for a dominance of local heating.

**Figure 9.** Radial PSD profiles at constant *μ* (4500 *MeV G* ) and *K* (0.1 *REG* 1 2 ) for RBSP-A/REPT electrons of energies between approximately 3 MeV and 7 MeV along both inbound and outbound crossings of the radiation belts. Complementary RBSP-B/REPT profiles (not shown) are consistent with their A counterpart.

#### **6. Conclusions**

The study of geomagnetic storms and other space weather phenomena is crucial to better understand the mechanisms taking place during solar events and to prevent their effects on technological and anthropic systems, such as reduced satellite operations, failures in spacecraft electronics, radio communication problems, etc.

On 25 August 2018, the CSES-01/HEPD particle rate meters were able to detect the effects of a G3-class, ICME-driven geomagnetic disturbance characterized by marked magnetosphere compression and plasmasphere erosion.

In our analysis, a depletion of HEPD count rate at the storm's main phase was observed, followed by a clear rate enhancement during its recovery phase. This increase was detected at L-shells -3 for electron energies above 3 MeV, and, to a lesser extent, at L-shells -4 for electron energies above 4.5 MeV. These results were consistent with the behavior of integral sub-MeV fluxes measured by the MEPED-90◦ electron telescope on board the NOAA19/POES satellite, over the same period. The enhancement of HEPD trigger rates suggested a phenomenon of acceleration of energetic electrons, which lasted several days. The discrimination between adiabatic radial transport and non-adiabatic local heating was made by inspection of the PSD profiles of the REPT magnetospheric electrons from late 26 August to early 30 August, whose negative gradients were in favour of the latter, with corroboration by persistent chorus wave interactions previously revealed by other payloads on board the CSES-01 for the same storm.

During the recovery phase, the HEPD trigger rate enhancement was in coincidence with prolonged and intense substorm activity (> 1000 nT), as measured by the AL index. This followed the HEPD orbits crossing the auroral oval region, which expanded during the storm and was marked by UV enhancement especially in the Southern Hemisphere, as detected by the SSUSI instrument on board the DMSP satellite. This occurrence showed that auroral processes cannot be neglected when studying the dynamics of particle acceleration in the ORB, since energetic electrons undergo quick acceleration on typical timescales of auroral substorms.

Considering the sky-rocketing focus on space weather studies in this last decade, HEPD's results prove promising, especially in view of the already-planned constellation of CSES satellites in the next few years (CSES-02 is currently under construction). It is worth noticing that this set of satellites will take shape in a period when several other missions, which contributed to the monitoring of the near-Earth environment, will be either deactivated or well beyond the end of their scheduled lifetimes.

**Author Contributions:** Writing—original draft, F.P. (Francesco Palma); conceptualization, M.M. (Matteo Martucci), M.P. (Mirko Piersanti), and R.S.; writing—review and editing, A.S., A.P., M.M. (Matteo Martucci), M.P. (Mirko Piersanti), F.M.F., R.I., A.O., E.R., and R.S.; designing the experiment or calibration or data production and processing, A.S., A.P., S.B., R.B., W.J.B., D.C., L.C. (Luca Carfora), G.C., L.C. (Livio Conti), A.C., G.D., C.D.D., C.D.S., F.M.F., R.I., I.L., N.M., G.M., M.M. (Matteo Mergé), A.O., G.O., F.P. (Federico Palmonari), B.P., F.P. (Francesco Perfetto), P.P., M.P. (Michele Pozzato), E.R., M.R., S.B.R., Z.S., V.S., V.V., S.Z., and P.Z. All authors read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** CSES/HEPD data can be found at www.leos.ac.cn/ (accessed on 3 April 2021).

**Acknowledgments:** This work made use of data from the CSES-01 mission, a project funded by the China National Space Administration (CNSA), the China Earthquake Administration (CEA) in collaboration with the Italian Space Agency (ASI), the National Institute for Nuclear Physics (INFN), the Institute for Applied Physics (IFAC-CNR), and the Institute for Space Astrophysics and Planetology (INAF-IAPS). We kindly acknowledge the OMNIWeb website (https://omniweb. gsfc.nasa.gov/, accessed on 3 April 2021) for providing part of the data used in this paper. This work was supported by the Italian Space Agency in the framework of the "Accordo Attuativo 2020- 32.HH.0 Limadou Scienza+" (CUP F19C20000110005) and the ASI-INFN Agreement No.2014-037-R.0, Addendum 2014-037-R-1-2017. M. Piersanti thanks the ISSI-BJ project "the electromagnetic data validation and scientific application research based on CSES satellite" and Dragon 5 cooperation 2020-2024 (ID. 59236).

**Conflicts of Interest:** The authors declare no conflict of interest.

#### **References**


Acknowledgements

I would like to express my sincere gratitude to Prof. Chinghua Hung and all members in Precision Engineering and Simulation Laboratory, Department of Mechanical Engineering, National Chiao Tung University (Taiwan), for their support in all the time of writing this manuscript.

My sincere thanks also go to my husband, my son, and all members of my family for their encouragement so that I could finish this manuscript.


**12. ILM peeling technique**

### **12.1 Initiation**

The creation of an ILM flap is a crucial step in ILM peeling. The ideal starting point has been suggested as about 1000 microns above or below the fovea. A small ILM tear is created on the retinal surface by scraping the retinal surface with a diamond-dusted or using picks, bent MVR blades or with dedicated ILM forceps using a pinch and peel technique. Many surgeons utilise custom-designed micro forceps to pinch and lift the ILM and create a small flap to then grasp and customise the direction and shape of the desired flap (**Figure 10**).

### **12.2 Flap creation**

Vitreoretinal forceps and the diamond-dusted membrane scraper are valuable tools for flap creation [54]. The majority of surgeons tend to peel an ILM area of about one disk diameter around the fovea, releasing enough retinal tissue in order to allow macular hole closure (**Figure 11**). A broader area of ILM up to 3 disk diameters may be removed to improve retinal compliance and subsequent retinal closure but it is still unclear regarding the exact dimension of ILM removal needed.

**Figure 10.** *The finesse SHARKSKIN ILM forceps.*

**Figure 11.** *ILM flap folded over the macular hole.*

## **12.3 Side effects**

ILM peeling is one of the most demanding procedures in ophthalmic surgery requiring a high level of manual dexterity. Retinal damage can occur at the initial ILM flap creation point resulting in retinal haemorrhages and nerve fibre layer damage as well as iatrogenic eccentric retinal holes have been reported [55]. A peculiar retinal alteration in the area where the ILM is removed has been described as Disassociated

Optic Nerve Fibre Layer (DONFL) with a characteristic change in inner retinal morphology and appears related to Muller cell end plate damage [56–58].

#### **12.4 ILM peeling variants**

#### *12.4.1 Foveal sparing peeling*

This technique entails ILM removal but sparing a circular area of 400 microns around the MH rim. In a study by HO [59] foveal sparing resulted in better visual acuity and postoperative anatomy, based on the concept that Muller cells are important for maintaining foveal architecture. Muller cells may improve light transmission to the photoreceptors [60].  The latter group demonstrated a greater increase in foveal sensitivity following surgery. Muller cells preservation may therefore provide a better functional outcome after macular hole surgery [62, 63].

#### *12.4.2 ILM abrasion*

Mahajan [64] reported a different procedure to reduce trauma during ILM removal by using a diamond-dusted membrane scraper (DDMS) in circumferential and centripetal motions around the MH. This procedure was thought to encourage glial cell activation, losing ILM attachment to the underlying retinal tissue and ultimately encouraging MH closure.

ILM peeling was initially described in 1997 by Eckardt [25]. The rationale for ILM peeling was the removal of residual adherent vitreous cortex remnants, thereby increasing retinal compliance. ILM serves as a scaffold for cellular proliferation, and its removal should encourage MH closure. Peeling the ILM ensures the thorough removal of any tangential tractional components implicated in the development of macular holes. The removal of a potential scaffold for the re-proliferation of myofibroblasts may reduce the possibility of late reopening of surgically closed holes. Furthermore, peeling off the ILM is also believed to stimulate wound healing at the macula, possibly by inducing local expression of growth factors that promote glial repair (**Video 1**, http://bit.ly/433B3XW).

The Cochrane database of systemic reviews concluded in 2013 that there was enough evidence to support the positive effects of ILM peeling for stages 2–4 idiopathic MH's to improve the primary anatomical hole closure rate, although no clear benefit was found for small holes [24].

ILM peeling increases the likelihood of successful macular hole closure, but it has been suggested that the extra manipulation of this membrane at the time of surgery could be harmful to the retina.

Swelling of the arcuate nerve fibre layer after internal limiting membrane peeling was described by Clark [65]. Electrophysiologic studies using focal macular electroretinogram showed a delayed recovery of the b-wave 6 months after macular hole surgery in eyes that underwent ILM peeling compared to those without peeling [66].

Although anatomical closure achieved after complete ILM peeling was associated with improved visual outcomes, the rate of anatomic closure was inversely correlated with the extent of ILM peeling actually achieved. It was suggested that excessive unsuccessful attempts at ILM peeling might enhance anatomic success (possibly

through enhanced promotion of glial healing) at the expense of poorer visual outcomes, presumably resulting from damage to inner retinal elements [67].

Inner limiting membrane peeling appears to improve the rate of anatomical closure, but its effect on visual outcome is less predictable and unsuccessful attempts to peel the ILM are associated with poor visual outcome. While ILM peeling may be performed for full-thickness macular holes of any stage, it is more commonly reserved for stage 3 or 4 holes, long-standing holes, those that have failed to close, or those that have re-opened following conventional surgery.

ILM peeling is thought to be beneficial for macular hole closure and in particular for large holes, however, it may also cause side effects on retinal anatomy and functionality. Retinal changes described after ILM peeling included inner retinal dimpling [68], dissociated retinal nerve fibre layer (RNFL), [69] and reduced parafoveal retinal thickness [70].

#### **13. Internal limiting membrane peel extension**

ILM peeling has improved surgical success in MH surgery. The ILM can be removed using forceps, diamond dusted scraper or other surgical tools and it has been suggested that at least 2 disc diameter (DD) of ILM should be removed around the fovea. Different surgeons perform this delicate procedure using peel radii from 0.5 to 3 DD. Bae et al. [71] compared peel sizes of 0.75 DD versus 1.5 DD and showed that a larger ILM peel lessens postoperative metamorphopsia. Modi et al. [72] have shown similar results in MH closure rates with 3 mm versus 5 mm peel sizes. No consensus on optimal peel width exists, but case reports of wide peels having success in large MHs have led many surgeons to peel ILM up to the arcades [73].

#### **13.1 Macular holes >400 microns**

In macular holes <400 microns conventional ILM peeling provided better functional outcomes compared with the inverted flap technique and should be advocated [74].

FTMH above 400 microns have a reduced rate of success with standard surgery, and other techniques such as ILM flaps and retinal expansion may be preferred for these macular holes [7]. Vitrectomy with the inverted ILM flap technique seems to be effective surgery for large idiopathic and myopic MHs, improving both functional and anatomical outcomes in a study by Rizzo [75] and surgical closure in all patients is reported in a study by Yamashita [76].

The practice of using the ILM on top of a macular hole has many effects, such as a bandage, isolating the retinal hole from the vitreous fluids, as a scaffold stimulating glial tissue proliferation, and will all encourage hole closure. In a study by Michalewska et al. [19] the use of ILM flap increased the rate of MH closure up to 98% for large MHs. This technique has also resulted in a 100% macular hole closure rate in myopic MH's reported in some studies [77, 78].

ILM flaps can be divided into two groups, inverted and non-inverted flaps: Inverted flaps

These flaps require the presence of ILM still hinged around the hole or near the hole in order to prevent displacement of ILM in the vitreous cavity. Michalewska [79] describes a procedure where the ILM is engaged with ILM forceps and removed almost in its entirely around the macular hole but a tiny residual attachment is left in place. Folded ILM is then packed inside the MH rather than a flap covering it. ILM is massaged into the MH from all sides until it becomes inverted and may be described as an 'ILM plug'. At a microscopic level, the presence of this plug may hamper outer retinal layer healing and prevent visual acuity recovery by interfering with photoreceptor reconstitution [80]. ILM tissue however is also known to work as a scaffold for tissue proliferation, promoting photoreceptors restoration and providing guidance for the correct positioning of the cells [81]. Rossi [82] stated that by using the fill technique, the ILM acts as a filler, glue, and scaffold all at the same time.

Shin [83] first introduced a true flap technique (single-layered flap of the ILM) for covering MH's (larger than 400 μm) with the assistance of perfluoro-n-octane (PFO) in 2014. Perflurocarbon liquid allows ILM flap stabilisation during fluid-air exchange by reducing dislocation or flap loss.

The temporal inverted internal limiting membrane flap was described by Michalewska [79]. The nasal ILM was left in place to protect the tissue from surgical trauma and lessen the occurrence of dissociated optic nerve fibre layer (DONFL).

The opposite approach has also been described and named the "Texas taco" [84]. This procedure involves peeling the nasal ILM and then it is folded temporally to cover the MH.

Ghassemi et al. [85] investigated the results of different ILM flap directions. The techniques used were a hemi circular ILM peel with a temporally hinged inverted flap, a circular ILM peel with a temporally only hinged inverted flap and a circular ILM peel with a superior inverted flap. Similar results were obtained with all flap directions.

Aurora [86] described the Cabbage Leaf Inverted Internal Limiting Membrane Flap technique. Three inverted ILM flaps sealed the hole looking like cabbage leaves. These flaps were connected to the edge of the MH, trimmed and flipped over the MH, one above the other like seen with cabbage leaves.

In cases when the central ILM had already been removed during previous surgery, Tabandeh [87] described the SWIFT flap procedure. An ILM flap is fashioned from superior residual ILM then a narrow strip of residual ILM forms the base of the flap, which is positioned horizontally. The ILM flap is inverted over the macular hole and covers the MH and the retina inferior to the MH **Figures 12** and **13**.

Leisser [88] described a technique where a temporal ILM flap was prepared while the residual ILM around the MH was peeled to the rim of the MH, after which the ILM flap was positioned in an inverted fashion over the MH (**Figures 14** and **15**).

The pedunculated flap technique creates an ILM flap that covers the macular hole from the border of the previous ILM peel. The flap should be large enough to cover the region of the pre-existing ILM peel as well as the macular hole.

**Figure 12.** *SWIFT (superior wide-based FLAP transposition) FLAP.*

**Figure 13.** *Macular holes covered with inverted ILM.*


*3.1. Weight Loss*

With respect to anthropometric parameters, our results showed that the improvement in body weight and composition induced by consumption of 500 mg per day brown seaweed extract rich in polyphenols with dietary modifications aimed at moderate weight loss was not greater than that provoked by dietary modifications alone. The lack of additional weight loss is consistent with recent data from Derosa et al. [27], who reported no effect of 6-month administration of food supplement containing *Ascophyllum nodosum* and *Fucus vesiculosus* extract and chromium picolinate on body weight and BMI in dysglycemic subjects. On the other hand, De Martin and co-authors [26] reported a significant decrease in waist circumference in overweight and obese subjects after 6 months of treatment with the same nutraceutical combination that had been administered in the study by Derosa et al. [27]. In light of these studies, it is possible that a reducing effect of brown seaweed extract on body weight was masked by the effect of the low-calorie diet in the present study. It is also to be considered that the absence of additional weight loss could be attributed to the dysglycemic status of our subjects or to the absence of chromium picolinate in the supplement.


**Game-Based Learning, Gamification in Education and Serious Games**

Editors **Carlos Vaz de Carvalho Antonio Coelho**

MDPI ' Basel ' Beijing ' Wuhan ' Barcelona ' Belgrade ' Manchester ' Tokyo ' Cluj ' Tianjin

*Editors* Carlos Vaz de Carvalho GILT School of Engineering of the Porto Polytechnic Porto Portugal

Antonio Coelho Computer Eng. Faculty of Engineering of the Porto University Porto Portugal

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