Symmetry and stability of orientationally ordered collective motions of self-propelled, semiflexible filaments

Ordered, collective motions commonly arise spontaneously in systems of many interacting, active units, ranging from cellular tissues and bacterial colonies to self-propelled colloids and animal flocks. Active phases are especially rich when the active units are sufficiently anisotropic to produce liquid crystalline order and thus active nematic phenomena, with important biophysical examples provided by cytoskeletal filaments including microtubules and actin. Gliding assay experiments have provided a testbed to study the collective motions of these cytoskeletal filaments and unlocked diverse collective active phases, including states with long-range orientational order. However, it is not well-understood how such long-range order emerges from the interplay of passive and active aligning mechanisms. We use Brownian dynamics simulations to study the collective motions of semiflexible filaments that self-propel in quasi-two dimensions, in order to gain insights into the aligning mechanisms at work in these gliding assay systems. We find that, without aligning torques in the microscopic model, long-range orientational order can only be achieved when the filaments are able to overlap. The symmetry (nematic or polar) of the long-range order that first emerges is shown to depend on the energy cost of filament overlap and on filament flexibility. However, our model also predicts that a long-range-ordered active nematic state is merely transient, whereas long-range polar order is the only active dynamical steady state in systems with finite filament rigidity.Comment: Main text: 9 pages, 6 figures. Supplementary Material: 5 pages, 5 figures. For associated video files, see https://livejohnshopkins-my.sharepoint.com/:f:/g/personal/mathani1_jh_edu/EmZKBH1qRzJFmK1mXTr32BUBfu2xJk1yesRJ3NyUo1ueRQ?e=LPRud

Clinico-social Profile of Chikungunya Cases Reported in 2016 at a Tertiary Care Hospital in New Delhi

Background: Chikungunya epidemic is a public health problem in South-East Asian countries.There was an epidemic of chikungunyain the year 2016 in New Delhi. Therefore, this present study was planned to understand the epidemiological profile of Chikungunya cases attending fever clinic in a tertiary care hospital in New Delhi.Objective: To studyepidemiological and clinical profile of Chikungunya cases attending fever clinic in Safdarjung Hospital.Methods: A total of 200 patients with fever of up to 7days duration were enrolled at fever clinic of VMMC and Safdarjung Hospital, New Delhi from May 2016 to October 2016.Total number of 47874 fevercases were reported in fever clinic from May 2016 to October 2016. A preformed semi-structured, intervieweradministeredquestionnairewas used for data collection. Serum specimens were screened for chikungunya infection by serology (IgM). Chikungunya infection was detected in 16.5% patients byanti- CHIKV IgM antibodies by ELISA.Results: Among these 200 suspected cases of chikungunya, fever (96.0%),joint pain (81.0%),Myalgia (77.5%) and lower backache (57.5%) were the major clinical features. Major joints involved were knee joint (45.5%), wrist (32.5%), hand (phalanges) (34.5%) and ankle joints (31.0%). Myalgia, rashes, joint painand joint swelling was frequently observed among chikungunya confirmed cases (p<0.05). All group of ages, both gender and all class of socioeconomic scale were equally susceptible to chikungunya infection.Conclusion: Chikungunya virus had a wide spectrum of clinical features and all age groups, gender and socioeconomic status people were equally susceptible to Chikungunya infection.All acute febrile illness patients with joint pain shouldbe screened in the laboratory for both Chikungunya IgM antibodies.Predictability of chikungunya is more in presence of joint pain and swelling, myalgia and rashes. This study emphasizes the need for a continuous surveillance on the disease burden