A note on the power distribution between symmetric and anti-symmetric components of the tropical Brightness Temperature spectrum in the wavenumber-frequency plane

A recent study observed the existence of a salient bias towards the symmetric part of the tropical wavenumber-frequency spectrum. Examination of the tropical Brightness Temperature (BT) spectrum in this note shows that its parity difference, i.e., the difference between its symmetric and anti-symmetric components, is concentrated in regions of the wavenumber-frequency plane corresponding to the spectral bands suggested by Wheeler and Kiladis (1999). In terms of the difference between the spectral power in the symmetric and anti-symmetric components, the spectral bands corresponding to Kelvin waves, Madden-Julian Oscillation, and Rossby waves explain about 31%, 21%, and 13% of the symmetric bias, respectively, while the combined contribution of all the other bands is negligible. The “background” spectrum after filtering out all the spectral bands explains the remaining 35% of the symmetric bias. As these spectral bands were originally designed for filtering convectively coupled equatorial waves, the findings of this note may help estimate the contributions of different wave features to the symmetric bias in the tropical BT spectrum. In addition, these findings may also help better understand the processes responsible for generating the tropical background spectrum.

BLACK SEA SECURITY AND ASYMMETRIC MILITARY THREATS IN THE 21ST CENTURY: NEW TRENDS AND NEW CHALLENGES

The Black Sea region is increasingly becoming a priority on the international agenda. In fact, a regional approach is emerging as actors understand that common problems need tobe addressed jointly. Nevertheless, cooperation efforts are hampered by a number of factors, such as uneven economic and political development within and among countries, nationalist forces, and longstanding animosities between regional players. In this context, it is imperative to foster sound policies aimed at strengthening dialogue and cooperation so as to contain and ultimately resolve conflicts with peaceful means. However, there is little policy-oriented research on the challenges and opportunities for cooperation in the Black Sea region. The purpose of this paper is to assess the impact of terrorism and its dangers towards the Black Sea region. The work also describes the significance of international terrorism and its general definitions. Besides, the result and findings are based on theoretical studies and assumptions and the result of the analysis of the "Case Study" of the Black Sea region. Case study examines how the Black Sea region influences the spread of terrorism and what threats it poses for this region. Furthermore, the aspects of what makes the region important on international arena are analyzed and the existent and potential security issues are examined, as well as strategicimportance of the region for the EU and NATO is analyzed even from academic framework –“Securitization” theory322. The theory is based on security studies conceptual background and the background spectrum includes: the Copenhagen School and Critical security studies as the type323.Keywords: Black Sea region, Copenhagen School, Critical security studies, Securitization,NATO, EU, Georgia’s national security

Sero-prevalence of SARS CoV-2 specific antibody among general population of Tripura, India: A baseline observation

Background: Spectrum of COVID-19 disease ranges from asymptomatic or mild symptomatic to life threatening cases. Population based sero-epidemiological studies are useful for assessing the magnitude of COVID-19 infection in a geographic area and it is helpful for planning control measures. Objectives: To estimate the sero-prevalence of SARS CoV-2 antibody in the general population of Tripura and to study the factors associated with it. Methodology: This community based cross-sectional study was conducted from 15th October to 14th November 2020 among 4800 subjects selected from the whole state of Tripura, India by probability proportionate to size sampling technique using 30 clusters. Electrochemiluminescence (eCLIA) based assay was used to test the serum samples for SARS-CoV-2 specific antibody. Data entry and analysis was performed using SPSS-25 for windows and sero-prevalence was expressed in percentages. Binary logistic regression model was used for predicting sero-positivity by including the significant factors associated with SARS-CoV-2 infection as found out by univariate analysis. Result: Sero-prevalence of SARS-CoV-2 antibody was found to be 34% among the general population of Tripura and it varied from 42.4% to 19.7% across different districts. Logistic regression model has identified, urban residency (OR: 1.21, 95% CI: 1.03-1.42), ethnic community (OR: 0.55, 95% CI: 0.48-0.64) and literacy (OR: 1.41, 95% CI: 1.13-1.77) as the independent risk factors for SARS-CoV-2 sero-positivity (p<0.05). Conclusion: Approximately one out of three residents of Tripura has already acquired the novel SARS CoV-2 infection. As the threshold required for achieving herd immunity against COVID-19 is not yet known, control measures need to be continued for preventing further spread of disease in the community.

Effects of the Background Turbulence on the Relaxation of Ion Temperature Anisotropy in Space Plasmas

Turbulence in space plasmas usually exhibits two regimes separated by a spectral break that divides the so called inertial and kinetic ranges. Large scale magnetic fluctuations are dominated by non-linear MHD wave-wave interactions following a −5/3 or −2 slope power-law spectrum. After the break, at scales in which kinetic effects take place, the magnetic spectrum follows a steeper power-law k−α shape given by a spectral index α &gt; 5/3. Despite its ubiquitousness, the possible effects of a turbulent background spectrum in the quasilinear relaxation of solar wind temperatures are usually not considered. In this work, a quasilinear kinetic theory is used to study the evolution of the proton temperatures in an initially turbulent collisionless plasma composed by cold electrons and bi-Maxwellian protons, in which electromagnetic waves propagate along a background magnetic field. Four wave spectrum shapes are compared with different levels of wave intensity. We show that a sufficient turbulent magnetic power can drive stable protons to transverse heating, resulting in an increase in the temperature anisotropy and the reduction of the parallel proton beta. Thus, stable proton velocity distribution can evolve in such a way as to develop kinetic instabilities. This may explain why the constituents of the solar wind can be observed far from thermodynamic equilibrium and near the instability thresholds.

Effects of the Background Turbulence on the Relaxation of Ion Temperature Anisotropy in Space Plasmas

&lt;p&gt;Turbulence in space plasmas usually exhibits two regimes separated by a spectral break that divides the so called inertial and kinetic ranges. Large scale magnetic fluctuations are dominated by MHD non-linear wave-wave interactions following a -5/3 or -3/2 slope power-law spectrum. After the break, at scales in which kinetic effects take place, the magnetic spectrum follows a steeper power-law &lt;em&gt;k&lt;sup&gt;- &amp;#945;&lt;/sup&gt;&lt;/em&gt; shape given by a spectral index &lt;em&gt;&amp;#945; &lt;/em&gt;&gt; 5/3. The location of the break and the particular value of &lt;em&gt;&amp;#945;, &lt;/em&gt;depend on plasma conditions, and different space environments can exhibit different spectral indices. Despite its ubiquitousness, the possible effects of a turbulent background spectrum in the quasilinear relaxation of solar wind temperatures are usually not considered. In this work, a quasilinear kinetic theory is used to study the evolution of the proton temperatures in a solar wind-like plasma composed by cold electrons and bi-Maxwellian protons, in which electromagnetic waves propagate along a background magnetic field. Four wave spectrum shapes are compared with different levels of wave intensity. We show that a sufficient turbulent magnetic power can drive stable protons to transverse heating, resulting in an increase in the temperature anisotropy and the reduction of the parallel proton beta. Thus, stable proton velocity distribution can evolve in such a way as to develop kinetic instabilities. This may explain why the constituents of the solar wind can be observed far from thermodynamic equilibrium and near the instability thresholds.&lt;/p&gt;

Westward-propagating Rossby modes in idealized GCMs

This work investigates the characteristics of westward-propagating Rossby modes in idealized global general circulation models. Using a nonlinear smoothing algorithm to estimate the background spectrum and an objective method to extract the spectral peaks, the 4 leading meridional modes can be identified for each of the first 3 zonal wavenumbers, with frequencies close to the predictions from the Hough modes obtained by linearizing about a state of rest. Variations in peak amplitude for different modes, both within a simulation and across simulations, may be understood under the assumption that the forcing of the modes scales with the background spectrum. Surface friction affects the amplitude and width of the peaks but both remain finite as friction goes to zero, which implies that some other mechanism, arguably nonlinear, must also contribute to the damping of the modes. Although spectral peaks are also observed for the precipitation field with idealized moist physics, there is no evidence of mode enhancement by the convective heating. Subject to the same friction, the amplitude of the peaks are very similar in the dry and moist models when both are normalized by the background spectra.

The role of claw colouration in fiddler crabs’ mate choice: Private communication channel or handicap?

Colour cues play an important role in sexual selection and conspecific recognition. Literature shows that conspecifics might enjoy their everyday chat, without ever worrying about occasional eavesdroppers (e.g., predators), when information interchange evolves into a private communication channel. Yet, when signalling is converted into foraging cues by predators, their prey must pay the due cost for sustaining conversation. For that matter, fiddler crabs draw attention for having flashy enlarged claws that could potentially attract the attention of many predators. Surprisingly, the costs associated with claw colouration in fiddler crabs are still poorly understood and have never been studied in American species. Here, we initially examine whether hypertrophied claws of American thin-fingered fiddler crabs (Leptuca leptodactyla) reflect UV-light and how conspecific females react to these cues. Then we test two alternative hypotheses concerning the role of claw colouration in fiddler crabs’ mate choice: a) that claw colouration evolved into a private communication channel, which could have significantly lowered signalling costs for males; b) that claw colouration is conspicuous to potential reproductive partners, as well as to predators, making colour signalling by males very costly (i.e., a handicap). Thereafter, we measured the reflectance spectra from several enlarged claws and modelled their chromatic contrast against the background spectrum, considering the visual systems of conspecific fiddler crabs and two kinds of predators (foxes and plovers). We also tested female conspecifics’ preference towards enlarged claws that reflected UV-light or other colour cues, by artificially altering claw colouration. Our results show a clear female preference for UV reflecting males. We also found that natural enlarged claws should be highly detectable by avian predators, refuting the private communication channel hypothesis. Furthermore, since female fiddler crabs select the most flamboyant claws from the sandy background, claw colouration in fiddler crabs can be understood as an honest signal.HIGHLIGHTSThe hypertrophied claws of male Leptuca leptodactyla reflect UV light.Female fiddler crabs display a natural preference for UV light cues.Male enlarged claws are conspicuous to birds and crabs, but cryptic to mammals.Conspicuous claws function as handicaps and may honestly signal individual quality.Our data refute the presence of a private communication channel in L. leptodactyla.

Revisiting cosmic microwave background radiation using blackbody radiation inversion

Blackbody radiation inversion is a mathematical process for the determination of probability distribution of temperature from measured radiated power spectrum. In this paper a simple and stable blackbody radiation inversion is achieved by using an analytical function with three determinable parameters for temperature distribution. This inversion technique is used to invert the blackbody radiation field of the cosmic microwave background, the remnant radiation of the hot big bang, to infer the temperature distribution of the generating medium. The salient features of this distribution are investigated and analysis of this distribution predicts the presence of distortion in the cosmic microwave background spectrum.

Pattern of pediatric renal diseases in a rural tertiary care hospital

Background: Spectrum of renal disease varies in different population, geographical location, and by environmental factors. The purpose of this study was to find out the occurrence of different pediatric renal diseases at a teaching hospital in the rural part of Maharashtra, India.Methods: All cases of renal diseases from one month to 12 years of age, admitted to the wards during the period of July 2018 to December 2019, were included in the study. Detailed clinical and laboratory evaluations were performed on all patients. Diseases were categorized as per standard definitions and managed with hospital protocols.Results: Renal diseases accounted to be 235 cases (2.8%) of total pediatric admissions during study period, of which (61.3%) were male and (38.7%) female. Nephrotic syndrome (NS), was the most common disorder (34%) followed by congenital anomalies of the kidney and the urinary tract (CAKUT) (24.7%), urolithiasis (11%), urinary tract infection (10.63%), chronic kidney disease (CKD) (7.66%) and acute kidney injury (AKI) (3.83%). The causes of AKI were dehydration, urosepsis, septicemia, and acute glomerulonephritis (AGN). Mortality was found in 3.4% of cases and the etiologies were AKI, NS and CKD.Conclusions: A substantial number of children are hospitalized with renal and urinary tract diseases. NS and congenital defects were the leading renal disorders in this study. These patients need comprehensive services for early identification and management.