Given an abstract, indicate which of the provided candidate titles (Option1 and Option2) best describes it (respond with the text of the title, not option1/2).

Ex Input:
Abstract: In the Drosophila embryo the establishment and specification of metameric units depends upon the selective activation of the segmentation and the homoeotic selector genes. The former are necessary for establishing the appropriate number of metameric or parasegmental units, whereas the latter control the pathways of differentiation followed by particular parasegments. Classical embryological manipulations have show n that these processes must be closely coordinated during normal development. However, previous studies of pair-rule genes have led to the suggestion that the specification of segmental identity proceeds independently of the establishment of metameres as physical units. These apparently conflicting perspectives can be reconciled by envisaging a common maternally derived positional information system which is independently interpreted by the components of both processes. In the case of the partitioning process, the gap and pair-rule genes would be instrumental in translating this information, whereas the activation of the homeotic genes would be mediated via other intermediaries (see ref. 9 for review). It is difficult to see, however, how such a system could ensure the precise regulation of the tw o types of genes implicit in the final differentiated pattern. This difficulty has led to the suggestion that the segmentation mechanism must define the precise boundaries of selector gene expression. Here we confirm this suggestion and propose that the gene fushi tarazu plays a key role in this process, integrating the processes of metameric partitioning and regional specification in the Drosophila embryo. 
 Which is the apt title for the abstract? option1: The correct activation of Antennapedia and bithorax complex genes requires the fushi tarazu gene. option2: Diagnostic radiology: usage and trends in the United States, 1964-1980.

Ex Output:
The correct activation of Antennapedia and bithorax complex genes requires the fushi tarazu gene.


Ex Input:
Abstract: Low-level activity at the end of the QRS complex was analyzed from 63 thoracic leads in 15 normal subjects and in 21 patients with ventricular tachycardia (VT). The latter had old myocardial infarction and no conduction disturbances and had not been receiving antiarrhythmic drugs. In both normal subjects and patients with VT, isopotential maps of the time-averaged and filtered (25 Hz high-pass) electrocardiograms during the terminal portion of the QRS were dipolar, i.e., they showed single positive and negative regions. For patients with VT, the extrema were either distant, with one over the precordial area and the other over the back, or close together in the precordial region. In 10 patients, maps recorded after administration of antiarrhythmic drugs remained the same while QRS duration was prolonged. In six patients, maps recorded before antiarrhythmic surgery showed distant extrema for septal or posterobasal VT sites of origin and close extrema for anterior or posteroapical sites. Generally, QRS duration was reduced and maps were modified after surgery. Late potentials can be well detected with only three orthogonal leads because their distributions are dipolar, but maps provide additional information about their distribution, which may be related to conduction delay sites and possibly to VT sites of origin. Sources near the torso surface would produce close extrema, whereas deeper sources would produce distant extrema. 
 Which is the apt title for the abstract? option1: Characterization of the spatial distribution of late ventricular potentials by body surface mapping in patients with ventricular tachycardia. option2: The strictures, sinuses, and fissures of Crohn's disease.

Ex Output:
Characterization of the spatial distribution of late ventricular potentials by body surface mapping in patients with ventricular tachycardia.


Ex Input:
Abstract: Twenty years of published experience with the Workman-Armstrong equation for predicting walking VO2 is reviewed. The equation is reexpressed in currently accepted terminology, and it is shown that the equation serves well as a basic model of normal walking. Employing this model to analyze VO2/step leads to the elaboration of a three-compartment model of the metabolic cost of walking. This three-compartment model provides a rational estimate of the fraction of walking's metabolic cost that powers the actual walking movement. Doubt is expressed that "comfortable speed of walking" is definable in energy terms. It is suggested that the requirements of maintaining balance while walking may determine both the comfortable speed of walking and the curvilinearity of the relationship between ground-speed and freely chosen step frequency of walking. 
 Which is the apt title for the abstract? option1: Metabolic cost of walking: equation and model. option2: The US health care system in the year 2000.

Ex Output:

Metabolic cost of walking: equation and model.


