The trick in building a vented box is to get the right size enclosure and the right size vent. You can't be too far off on either of these factors or your speaker's performance will suffer. In particular, using a too-small box or a too-high vent tuning frequency can eliminate bass instead of increasing it.
1 Dengue fever is a disease caused by a family of viruses that are transmitted by mosquitoes. 2  Symptoms include severe joint and muscle pain, swollen lymph nodes, headache, fever, exhaustion, and rash. 3  The presence of fever, rash, and headache (the dengue triad) is characteristic of dengue fever.
Dengue fever can also cause bleeding from the skin, nose, and gums. Recovery from dengue fever is often lengthy, lasting several weeks, and patients can experience lingering fatigue and depression. Infection with the dengue virus can also cause a disease called severe dengue, which is more serious than dengue fever. Although the early symptoms of severe dengue are similar to dengue fever, severe dengue has a much higher death rate.