Investigation of gas-gas immiscibility in mixtures of carbon tetrafluoride and n-alkanes

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Bounds on graviton mass using weak lensing and SZ effect in galaxy clusters

In General Relativity (GR), the graviton is massless. However, a common feature in several theoretical alternatives of GR is a non-zero mass for the graviton. These theories can be described as massive gravity theories. Despite many theoretical complexities in these theories, on phenomenological grounds, the implications of massive gravity have been widely used to put bounds on graviton mass. One of the generic implications of giving a mass to the graviton is that the gravitational potential will follow a Yukawa-like fall off. We use this feature of massive gravity theories to probe the mass of graviton by using the largest gravitationally bound objects, namely galaxy clusters. In this work, we use the mass estimates of galaxy clusters measured at various cosmologically defined radial distances measured via weak lensing (WL) and Sunyaev-Zel'dovich (SZ) effect. We also use the model independent values of Hubble parameter $H(z)$ smoothed by a non-parametric method, Gaussian process. Within $1\sigma$ confidence region, we obtain the mass of graviton $m_g < 5.9 \times 10^{-30}$ eV with the corresponding Compton length scale $\lambda_g > 6.82$ Mpc from weak lensing and $m_g < 8.31 \times 10^{-30}$ eV with $\lambda_g > 5.012$ Mpc from SZ effect. This analysis improves the upper bound on graviton mass obtained earlier from galaxy clusters.Comment: 9 Pages, 3 Figures, 2 Tables, Accepted for publication in Physics Letters

Monitoring cholesterol organization in membranes at low concentrations utilizing the wavelength-selective fluorescence approach

We previously showed using a fluorescent analogue of cholesterol (NBD-cholesterol, or 25-[N-[(7-nitrobenz-2-oxa-1,3-diazol-4-yl)-methyl]amino]-27-norcholesterol), that cholesterol may exhibit local organization at low concentrations in membranes by the formation of transbilayer tail-to-tail dimers of cholesterol (Rukmini, R., Rawat, S.S., Biswas, S.C., Chattopadhyay, A., 2001. Biophys. J. 81, 2122-2134). In this report, we have monitored the microenvironmental features of cholesterol monomers and dimers utilizing wavelength-selective fluorescence spectroscopy. Our results utilizing red edge excitation shift (REES) and wavelength-dependent change in fluorescence anisotropy show that the microenvironment around the NBD moieties in the dimer form is more rigid possibly due to steric constraints imposed by the dimer conformation. These results provide new information and are relevant in understanding the organization of cholesterol in membranes at low concentrations

Spin-flux attachment by dimensional reduction of vortices

The description of a system of vortices in terms of dual fields provides a window to new phases of the system. It was found recently that dualizing a 3+1-d boson-fermion system leads to a system of fermions and vortices interacting via a 2-form field through a non-local term. Here we explore some consequences of such an interaction when the degrees of freedom of the system are confined to a 2+1-d space-time. In particular, we show that the vortices in the 2+1-d system are attached to the fermions via their non-zero spin magnetic moment in a way similar to the phenomenon of flux attachment in Chern-Simons gauge theory coupled to matter. We also show that such flux attached particles exhibit fractional statistical behaviour like anyons. Thus our model provides a realization of anyons without Chern-Simons theory

Wavelength-selective fluorescence as a novel tool to study organization and dynamics in complex biological systems

The dynamics exhibited by a given component of a large macromolecule such as a folded globular protein or an organized supramolecular assembly like the biological membrane is a function of its precise localization within the larger system. A set of approaches based on the red edge effect in fluorescence spectroscopy, which can be used to monitordirectly the environment and dynamics around a fluorophore in a complex biological system, is reviewed in this article. A shift in the wavelength of maximum fluorescence emission toward higher wavelengths, caused by a shift in the excitation wavelength toward the red edge of the absorption band, is termed the red edge excitation shift (REES). This effect is mostly observed with polar fluorophores in motionally restricted media such as very viscous solutions or condensed phases. This phenomenon arises from the slow rates of solvent relaxation around an excited-state fluorophore, which is a function of the motional restriction imposed on the solvent molecules in the immediate vicinity of the fluorophore. Utilizing this approach, it becomes possible to probe the mobility parameters of the environment itself (which is represented by the relaxing solvent molecules) using the fluorophore merely as a reporter group. Further, since the ubiquitous solvent for biological systems is water, the information obtained in such cases will come from the otherwise optically silent water molecules. This makes REES and related techniques extremely useful in biology since hydration plays a crucial modulatory role in a large number of important cellular events

Government employment and pay : a global and regional perspective

The authors try to replace myths about government pay and employment with reliable facts from a survey for about 100 countries in the early 1900s. The study also outlines the general nature of civil service problems in the different regions. Nevertheless, while the facts are useful to"flag"possible problems and initiate a dialogue, recommendations for reform must be based on country-specific analysis. Globally, government employment is negatively associated with wages, and positively with the fiscal deficit (although the availability of financing is more important) and with per capita income (confirming"Wagner's Law"). But the global results stem almost entirely from strong results for Africa and Latin America. Civil service reform has suffered in the past from an overemphasis on retrenchment for fiscal reasons. Its true objective, for each country, is to achieve a civil service of the size and skill-mix, incentives, professional ethos, and accountability needed to provide public goods, help formulate and enforce the rules, and intervene to remedy market failures -as these government roles happen to be defined in the country in question. Civil service reform can begin with various diagnostic and fact-finding activities. The key measures concern rightsizing, incentives, and accountability. These are all relative notions: the right size of the workforce depends on the roles assigned to government; wage adequacy depends on private compensation levels; and strengthening of accountability must define accountability for what and to whom. When retrenchment is warranted, it must be carried out with great care to avoid skill reduction, demoralization, and lower-quality service. Adequate compensation is a must, and wage compression isto be avoided. But performance bonuses, popular in some advanced countries, have been only marginally effective in improving performance in developing countries, even in the private sector. And they can be dangerous in countries with ethnic, clan, or religious conflicts. Finally, improvements in accountability will most often require greater external openness and systematic feedback from service users.Banks&Banking Reform,Enterprise Development&Reform,Municipal Financial Management,Decentralization,Environmental Economics&Policies,National Governance,Banks&Banking Reform,Municipal Financial Management,Environmental Economics&Policies,Economic Policy, Institutions and Governance