4,333 research outputs found
Competition Among Rent Seeking Groups in General Equilibrium
A two sector general equilibrium model is developed in which households can influence the government's choice of the relative price of traded goods and the level of public goods supplied to each sector. The model is used to illustrate key problems addressed by the political economy literature, modeling issues that arise, and the nature of insights that can be obtained that traditional approaches cannot discern.General equilibrium, political economy, rent seeking, lobbying, Political Economy,
Describing many-body localized systems in thermal environments
In this work we formulate an efficient method for the description of fully many-body localized systems in weak contact with thermal environments at temperature T. The key idea is to exploit the representation of the system in terms of quasi-local integrals of motion (l-bits) to efficiently derive the generator for the quantum master equation in Born-Markov approximation. We, moreover, show how to compute the steady state of this equation efficiently by using quantum-jump Monte-Carlo techniques as well as by deriving approximate kinetic equations of motion. As an example, we consider a one-dimensional disordered extended Hubbard model for spinless fermions, for which we derive the l-bit representation approximately by employing a recently proposed method valid in the limit of strong disorder and weak interactions. Coupling the system to a global thermal bath, we study the transport between two leads with different chemical potentials at both of its ends. We find that the temperature-dependent current is captured by an interaction-dependent version of Mott's law for variable range hopping, where transport is enhanced/lowered depending on whether the interactions are attractive or repulsive, respectively. We interpret these results in terms of spatio-energetic correlations between the l-bits
Millimeter and sub-millimeter atmospheric performance at Dome C combining radiosoundings and ATM synthetic spectra
The reliability of astronomical observations at millimeter and sub-millimeter
wavelengths closely depends on a low vertical content of water vapor as well as
on high atmospheric emission stability. Although Concordia station at Dome C
(Antarctica) enjoys good observing conditions in this atmospheric spectral
windows, as shown by preliminary site-testing campaigns at different bands and
in, not always, time overlapped periods, a dedicated instrument able to
continuously determine atmospheric performance for a wide spectral range is not
yet planned. In the absence of such measurements, in this paper we suggest a
semi-empirical approach to perform an analysis of atmospheric transmission and
emission at Dome C to compare the performance for 7 photometric bands ranging
from 100 GHz to 2 THz. Radiosoundings data provided by the Routine
Meteorological Observations (RMO) Research Project at Concordia station are
corrected by temperature and humidity errors and dry biases and then employed
to feed ATM (Atmospheric Transmission at Microwaves) code to generate synthetic
spectra in the wide spectral range from 100 GHz to 2 THz. To quantify the
atmospheric contribution in millimeter and sub-millimeter observations we are
considering several photometric bands in which atmospheric quantities are
integrated. The observational capabilities of this site at all the selected
spectral bands are analyzed considering monthly averaged transmissions joined
to the corresponding fluctuations. Transmission and pwv statistics at Dome C
derived by our semi-empirical approach are consistent with previous works. It
is evident the decreasing of the performance at high frequencies. We propose to
introduce a new parameter to compare the quality of a site at different
spectral bands, in terms of high transmission and emission stability, the Site
Photometric Quality Factor.Comment: accepted to MNRAS with minor revision
Joint density-functional theory for electronic structure of solvated systems
We introduce a new form of density functional theory for the {\em ab initio}
description of electronic systems in contact with a molecular liquid
environment. This theory rigorously joins an electron density-functional for
the electrons of a solute with a classical density-functional theory for the
liquid into a single variational principle for the free energy of the combined
system. A simple approximate functional predicts, without any fitting of
parameters to solvation data, solvation energies as well as state-of-the-art
quantum-chemical cavity approaches, which require such fitting.Comment: Fixed typos and minor updates to tex
Sun-photometric measurements of atmospheric turbidity variations caused by the Pinatubo aerosol cloud in the Himalayan region during the summer periods of 1991 and 1992
Measurements of direct solar irradiance were taken episodically on two days of September 1990 and regularly in the summer periods from July to October 1991 and from
mid-July to mid-August 1992 at the Pyramid Laboratory (5050 m a.m.s.l.) situated at the foot of Mt. Everest (Nepal), using two examples of the Volz multispectral sunphotometer, model A. These sun-photometric measurements were analysed in terms of the Bouguer-Lambert-Beer law in order to
determine the values of aerosol optical thickness at the three sun-photometric window-wavelengths. Examining these spectral series in terms of the well-known Ångström formula, the best-fit values of turbidity parameters a and b were calculated with great accuracy. From the measurements taken in September 1990, we found values of the aerosol optical thickness in good agreement with the mean values of the background aerosol optical depth measured at the Mauna Loa Observatory (Hawaii) during the four-year period from 1988 to 1991. The spectral values of the aerosol optical thickness determined during the summer of 1991 show that the mean daily values of parameter b increased abruptly from about 0.06 to more than 0.16 from July 26 to 28, 1991, and then varied between 0.09 and 0.16 during the rest of the measurement period. Simultaneously, parameter a was found to decrease from more than 1.25 to 0.39 towards the end of July and to vary between 0.40 and 0.78 during September. These large variations of both atmospheric turbidity parameters have been attributed to the growth of the aerosol particles and to the consequent
changes in the size distribution curve of the Pinatubo aerosol particles. Analysing the variations of the stratospheric aerosol optical depth in terms of particle polydispersions consisting of a linear combination of a background aerosol monomodal model and a bimodal model representing the Pinatubo fresh aerosol particle size
distribution, the vertical mass loading of stratospheric aerosol particles was estimated to vary between 0.037 and 0.047 g m22 from July 24 to 27 and to increase to values ranging between 0.048 and 0.074 g m22 during the rest of summer 1991, presenting a mean value of (0.063 6 0.009) g m22 for the two-month period. The measurements taken in summer 1992 show that parameter b ranged between 0.08 and 0.12, while parameter a was found to vary between 0.23 and 0.73. The stratospheric aerosol depth values were analysed through a best-fit procedure based on a linear combination of a background model of small aerosol particles and a trimodal model consisting of aged volcanic aerosol particles. Following this procedure, the vertical mass loading of Pinatubo aerosol particles was found to vary between 0.043 and 0.057 g m22 during summer 1992, the mean value being evaluated as equal to (0.047 6 0.004) g m22
Observation of coherent electroproduction on deuterons at large momentum transfer
The first experimental results for coherent -electroproduction on the
deuteron, , at large momentum transfer, are reported. The
experiment was performed at Jefferson Laboratory at an incident electron energy
of 4.05 GeV. A large pion production yield has been observed in a kinematical
region for 1.11.8 GeV, from threshold to 200 MeV excitation energy
in the system. The -dependence is compared with theoretical
predictions.Comment: 26 page
Single-cell RNA analysis of type I spiral ganglion neurons reveals a Lmx1a population in the cochlea
In the mature cochlea, each inner hair cell (IHC) is innervated by multiple spiral ganglion neurons of type I (SGNI). SGNIs are morphologically and electro-physiologically diverse. Also, they differ in their susceptibility to noise insult. However, the molecular underpinnings of their identity and physiological differences remain poorly understood. In this study, we developed a novel triple transgenic mouse, which enabled the isolation of pure populations of SGNIs and the analysis of a 96-gene panel via single-cell qPCR. We found three distinct populations of Type I SGNs, which were marked by their exclusive expression of Lmx1a, Slc4a4, or Mfap4/Fzd2, respectively, at postnatal days P3, P8, and P12. Our data suggest that afferent SGN subtypes are established genetically before the onset of hearing and that the expression of key physiological markers, such as ion channels, is heterogeneous and may be underlying the heterogeneous firing proprieties of SGNIs
Ive Got My Virtual Eye On You: Remote Proctors And Academic Integrity
This paper discusses the challenges of online teaching, the reasons students cheat and one means of curtailing that cheating in the online environment. The use of Securexam Remote Proctor System in one university application is reviewed
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