Pilot study of vegetation in the Alchichica-Perote region by remote sensing

A study of the application of satellite images to the identification of vegetation in a small area corresponding to the arid zone of Veracruz and part of Puebla is presented. This study is accomplished by means of images from the LANDSAT satellite obtained on January 19 and May 23, 1973. The interpretation of the different maps is made on the basis of information from the data bank of the Flora de Veracruz program, and various surveys made by land and air

Aerosol–precipitation elevation dependence over the central Himalayas using cloud-resolving WRF-Chem numerical modeling

Atmospheric aerosols can modulate the orographic precipitation impacting the evolution of clouds through radiation and microphysical pathways. This study implements the cloud-resolving Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) to study the response of the central Himalayan elevation-dependent precipitation to the atmospheric aerosols. The first monsoonal month of 2013 is simulated to assess the effect of aerosols through radiation and cloud interactions. The results show that the response of diurnal variation and precipitation intensities (light, moderate, and heavy) to aerosol radiation and cloud interaction depended on the different elevational ranges of the central Himalayan region. Below 2000 m a.s.l., the total effect of aerosols resulted in suppressed mean light precipitation by 19 % while enhancing the moderate and heavy precipitation by 3 % and 12 %, respectively. In contrast, above 2000 m a.s.l., a significant reduction of all three categories of precipitation intensity occurred with the 11 % reduction in mean precipitation. These contrasting altitudinal precipitation responses to the increased anthropogenic aerosols can significantly impact the hydroclimate of the central Himalayas, increasing the risk for extreme events and influencing the regional supply of water resources.</p

Improving Reliability of Subject-Level Resting-State fMRI Parcellation with Shrinkage Estimators

A recent interest in resting state functional magnetic resonance imaging (rsfMRI) lies in subdividing the human brain into anatomically and functionally distinct regions of interest. For example, brain parcellation is often used for defining the network nodes in connectivity studies. While inference has traditionally been performed on group-level data, there is a growing interest in parcellating single subject data. However, this is difficult due to the low signal-to-noise ratio of rsfMRI data, combined with typically short scan lengths. A large number of brain parcellation approaches employ clustering, which begins with a measure of similarity or distance between voxels. The goal of this work is to improve the reproducibility of single-subject parcellation using shrinkage estimators of such measures, allowing the noisy subject-specific estimator to "borrow strength" in a principled manner from a larger population of subjects. We present several empirical Bayes shrinkage estimators and outline methods for shrinkage when multiple scans are not available for each subject. We perform shrinkage on raw intervoxel correlation estimates and use both raw and shrinkage estimates to produce parcellations by performing clustering on the voxels. Our proposed method is agnostic to the choice of clustering method and can be used as a pre-processing step for any clustering algorithm. Using two datasets---a simulated dataset where the true parcellation is known and is subject-specific and a test-retest dataset consisting of two 7-minute rsfMRI scans from 20 subjects---we show that parcellations produced from shrinkage correlation estimates have higher reliability and validity than those produced from raw estimates. Application to test-retest data shows that using shrinkage estimators increases the reproducibility of subject-specific parcellations of the motor cortex by up to 30%.Comment: body 21 pages, 11 figure

Elevational richness patterns of sphingid moths support area effects over climatic drivers in a near‐global analysis

Not sure if this is the pre-refereed or final submitted version.Aim We test hypotheses on the environmental control of elevational richness patterns of sphingid moths for their global applicability and generality. Specifically, we compare effects of area with climate‐related drivers, such as primary productivity and temperature, while also considering direct effects of precipitation. Major taxa Sphingid moths (Lepidoptera). Location Eighty‐six mountain ranges of the Old World and the Australia/Pacific region, from Scandinavia and Siberia through the African and Australasian tropics to South Africa and Southern Australia. Methods We used a large compilation of point locality records for 744 species, in addition to fine‐grained range maps derived from species distribution modelling of these records, to characterize the elevational pattern of species richness in 86 custom‐delineated mountain regions. For both types of data, we compared the effects of environmental drivers on richness by comparing standardized coefficients of multivariate models for pooled data after accounting for between‐region variation in richness. Results We observed varying patterns of elevational richness across the research region, with a higher prevalence of midpeaks in arid regions. We found overwhelming support for area as a main determinant of richness, modulated by temperature and productivity, whereas we detected no effect of precipitation. Main conclusions Area, productivity and temperature are the main environmental predictors explaining a large proportion of variability in sphingid richness. This is consistent not only with other elevational studies, but also with empirical and theoretical biodiversity research in a non‐elevational context (with the caveat of some unresolved issues in elevational area effects). However, distinct differences in elevational patterns remain even within the same mountain ranges when comparing with other Lepidoptera, that is, geometrid moths, which highlights the importance of understanding higher clade differentiation in ecological responses, within insects and in other groups.© 2019 John Wiley & Sons Ltd. This is the pre-peer reviewed version of the following article: Bärtschi, F, McCain, CM, Ballesteros‐Mejia, L, Kitching, IJ, Beerli, N, Beck, J. Elevational richness patterns of sphingid moths support area effects over climatic drivers in a near‐global analysis. Global Ecol Biogeogr. 2019; 28: 917– 927. https://doi.org/10.1111/geb.12903, which has been published in final form at doi:10.1111/geb.12903. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.

Third quantization: a general method to solve master equations for quadratic open Fermi systems

The Lindblad master equation for an arbitrary quadratic system of n fermions is solved explicitly in terms of diagonalization of a 4n x 4n matrix, provided that all Lindblad bath operators are linear in the fermionic variables. The method is applied to the explicit construction of non-equilibrium steady states and the calculation of asymptotic relaxation rates in the far from equilibrium problem of heat and spin transport in a nearest neighbor Heisenberg XY spin 1/2 chain in a transverse magnetic field.Comment: 24 pages, with 8 eps figures - few minor corrections to the published version, e.g. anti-symmetrizing the matrix given by eq. (27

Typhoid and Paratyphoid Cost of Illness in Pakistan: Patient and Health Facility Costs from the Surveillance for Enteric Fever in Asia Project II

Background: The objective of this study was to estimate the cost of illness from enteric fever (typhoid and paratyphoid) at selected sites in Pakistan. Methods: We implemented a cost-of-illness study in 4 hospitals as part of the Surveillance for Enteric Fever in Asia Project (SEAP) II in Pakistan. From the patient and caregiver perspective, we collected direct medical, nonmedical, and indirect costs per case of enteric fever incurred since illness onset by phone after enrollment and 6 weeks later. From the health care provider perspective, we collected data on quantities and prices of resources used at 3 of the hospitals, to estimate the direct medical economic costs to treat a case of enteric fever. We collected costs in Pakistani rupees and converted them into 2018 US dollars. We multiplied the unit cost per procedure by the frequency of procedures in the surveillance case cohort to calculate the average cost per case. Results: We collected patient and caregiver information for 1029 patients with blood culture-confirmed enteric fever or with a nontraumatic terminal ileal perforation, with a median cost of illness per case of US $196.37 (IQR, US$72.89-496.40). The median direct medical and nonmedical costs represented 8.2% of the annual labor income. From the health care provider perspective, the estimated average direct medical cost per case was US $50.88 at Hospital A, US$52.24 at Hospital B, and US $11.73 at Hospital C. Conclusions: Enteric fever can impose a considerable economic burden in Pakistan. These new estimates of the cost of illness of enteric fever can improve evaluation and modeling of the costs and benefits of enteric fever prevention and control measures, including typhoid conjugate vaccines

Molecular testing dynamics is reactive to COVID-19 incidence: Observations from the colombian experience

There was a positive correlation between molecular tests conducted and COVID-19 incidence and death rate (r = 0.79, p < 0.01 and r = 0.64, p < 0.01, respectively). The cointegration (ADF) test revealed a statistically significant and closely time-dependent stochastic structure between daily COVID-19 cases and number of molecular tests (ADF, -3.50; p < 0.01)

Stochastic dynamics and control of a driven nonlinear spin chain: the role of Arnold diffusion

We study a chain of non-linear, interacting spins driven by a static and a time-dependent magnetic field. The aim is to identify the conditions for the locally and temporally controlled spin switching. Analytical and full numerical calculations show the possibility of stochastic control if the underlying semi-classical dynamics is chaotic. This is achievable by tuning the external field parameters according to the method described in this paper. We show analytically for a finite spin chain that Arnold diffusion is the underlying mechanism for the present stochastic control. Quantum mechanically we consider the regime where the classical dynamics is regular or chaotic. For the latter we utilize the random matrix theory. The efficiency and the stability of the non-equilibrium quantum spin-states are quantified by the time-dependence of the Bargmann angle related to the geometric phases of the states.Comment: Journal-ref: to appear in J.Phys.