16 research outputs found
Entire solutions of hydrodynamical equations with exponential dissipation
We consider a modification of the three-dimensional Navier--Stokes equations
and other hydrodynamical evolution equations with space-periodic initial
conditions in which the usual Laplacian of the dissipation operator is replaced
by an operator whose Fourier symbol grows exponentially as \ue ^{|k|/\kd} at
high wavenumbers . Using estimates in suitable classes of analytic
functions, we show that the solutions with initially finite energy become
immediately entire in the space variables and that the Fourier coefficients
decay faster than \ue ^{-C(k/\kd) \ln (|k|/\kd)} for any . The
same result holds for the one-dimensional Burgers equation with exponential
dissipation but can be improved: heuristic arguments and very precise
simulations, analyzed by the method of asymptotic extrapolation of van der
Hoeven, indicate that the leading-order asymptotics is precisely of the above
form with . The same behavior with a universal constant
is conjectured for the Navier--Stokes equations with exponential
dissipation in any space dimension. This universality prevents the strong
growth of intermittency in the far dissipation range which is obtained for
ordinary Navier--Stokes turbulence. Possible applications to improved spectral
simulations are briefly discussed.Comment: 29 pages, 3 figures, Comm. Math. Phys., in pres
Major Advances in Monkeypox Vaccine Research and Development – An Update
Monkeypox (MPX) is a zoonotic disease that is endemic to the western and central regions of Africa and it is caused by monkeypox virus (MPXV), which is classified as a member of the Poxviridae family, specifically the Chordopoxvirinae subfamily, and the Orthopoxvirus genus. The current multiregional outbreak of MPX, which started in May of 2022, has since swiftly spread across the globe and thus has been declared a global public health emergency by the World Health Organization (WHO). Protective immunity against MPXV can be achieved by administering a smallpox vaccination, as the two viruses share antigenic properties. Although smallpox was declared eradicated in 1980, the vaccine campaign was halted the following year, leaving the population with significantly less immunity than it had before. The potential for human-to-human transmission of MPXV has grown as a result. Due to the lack of a particular treatment for MPX infection, anti-viral medications initially designed for the smallpox virus are being employed. However, the prognosis for MPX may vary depending on factors like immunization history, pre-existing illnesses, and comorbidities, even though the majority of persons who develop MPX have a mild, self-limiting illness. Vaccines and antiviral drugs are being researched as potential responses to the latest 2022 MPX epidemic. The first-generation smallpox vaccinations maintained in national stockpiles of several countries are not recommended due to not meeting the current safety and manufacturing criteria, as stated by the WHO. Newer, safer (second- and third-generation) smallpox vaccines, such as JYNNEOSTM, which has been licensed for the prevention of MPX, are indicated as potentially useful in the interim guideline. Studies on vaccines and antiviral drugs are still being investigated as possible remedies to the recent MPX outbreak. This mini-review article serves as a retrospective look at the evolution of smallpox vaccines from their inception in the 1700s to the current trends up to the end of year 2022, specifically for developing monkeypox vaccines
Diversity of marine molluscs in the bycatch from lobster nets, Erwadi, Gulf of Mannar
170-175The current study was carried out to document molluscs that are caught in lobster nets (Singhi valai), an indigenous gear operated by fishers in the Gulf of Mannar to harvest lobsters, crabs and fishes. This net is operated in depths up to 15 m from the traditional country craft, ‘Vallam’. A total of 73 species of marine molluscs from class Bivalvia (32 species belonging to 4 families) and Gastropoda (41 species belonging to 27 families) have been documented. Vulsella vulsella was dominant (12.35%) among bivalves whereas Lambis lambis was dominant (14.7%) among the gastropods. The family Veneridae in bivalves (29%) and the family Strombidae in gastropods (17%) contributed the highest among the documented molluscs