207 research outputs found

    Assessment of climatic risks in relation to the transport infrastructure of the northern regions of Russia

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    Theme. Infrastructure of transport systems of the permafrost zone of Russia, operated in conditions of global warming. Objectives. To quantify the risks of disrupting the functionality of transport infrastructure facilities, taking into account the soil and natural and climatic features in the territory of their operation. Methodology. Modeling the temperature dynamics of the soil massif, including the upper seasonal thawed layer and the lower layer of permafrost soil, identifying changes in its strength and deformation properties under the accepted scenario of climatic changes, assessing the impact of changes in the soil massif on the operational state and safety of various types of infrastructure facilities of transport systems (taking into account the appearance of additional precipitation of thawing soil and a decrease in its bearing capacity), determination of the values of predicted risks on a scale that is uniform for all types of objects. Results. New data have been obtained on the negative consequences of climate change for the infrastructure of transport systems in the permafrost zone of Russia. Under fairly conservative assumptions about a warming of 2 degrees Celsius, the risk of functional impairment for the road profile is predicted to be from 86 to 294 points on a 1000-point scale, and climatic risks increase with an increase in the temperature of permafrost. The magnitude of the expected risks in relation to the aerodrome pavement is approximately at the same level; these two types of objects are distinguished by the greatest resistance to climatic changes. Pile foundations are subject to risk ranging from 143 to 529 points. The most vulnerable to warming are strip and columnar foundations, for which the lowest risk value obtained during modeling is 389 points, and under unfavorable conditions (high-temperature permafrost in combination with low soil moisture), the risk increases to the maximum possible value of 1000 points. Implications. The risks of disrupting the functionality of infrastructural objects of the permafrost transport systems, predicted at warming up to 2 degrees Celsius, should be considered significant. With risks up to 400 points (road profile, airfield coverage), it is advisable to limit ourselves to monitoring the current state of the facility and, if necessary, restore its functionality. With risks from 400 to 600 points, it is recommended, and in case of risks over 600 points, it is mandatory to carry out preventive engineering and technical measures aimed at stabilizing the temperature regime of soils and preventing a sudden loss of functionality of individual elements of the transport system

    Central factorials under the Kontorovich-Lebedev transform of polynomials

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    We show that slight modifications of the Kontorovich-Lebedev transform lead to an automorphism of the vector space of polynomials. This circumstance along with the Mellin transformation property of the modified Bessel functions perform the passage of monomials to central factorial polynomials. A special attention is driven to the polynomial sequences whose KL-transform is the canonical sequence, which will be fully characterized. Finally, new identities between the central factorials and the Euler polynomials are found.Comment: also available at http://cmup.fc.up.pt/cmup/ since the 2nd August 201

    Kaposi's sarcoma associated with Wegener’s granulomatosi

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    A case of Kaposi's sarcoma development in a pt with Wegener's granulomatosis during immunosupres- sive treatment with cyclophosphane and prednisolone

    SPERMATOGENIC TESTICULAR FUNCTION IN MEN WITH CHRONIC UROGENITAL MONOTRICHOMONIASIS AND PATHOSPERMIA

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    We did not observed significant differences in levels of inhibin B and follicle-stimulating hormone in serum samples of men with chronic urogenital trichomoniasis and different spermogram. It confirmed that spermatogenic testicular function in these men is preserved

    Berry phases for the nonlocal Gross-Pitaevskii equation with a quadratic potential

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    A countable set of asymptotic space -- localized solutions is constructed by the complex germ method in the adiabatic approximation for the nonstationary Gross -- Pitaevskii equation with nonlocal nonlinearity and a quadratic potential. The asymptotic parameter is 1/T, where T≫1T\gg1 is the adiabatic evolution time. A generalization of the Berry phase of the linear Schr\"odinger equation is formulated for the Gross-Pitaevskii equation. For the solutions constructed, the Berry phases are found in explicit form.Comment: 13 pages, no figure

    Left/right asymmetry in Dyakonov–Tamm-wave propagation guided by a topological insulator and a structurally chiral material

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    The propagation of Dyakonov–Tamm waves guided by the planar interface of an isotropic topological insulator and a structurally chiral material, both assumed to be nonmagnetic, was investigated by numerically solving the associated canonical boundary-value problem. The topologically insulating surface states of the topological insulator were quantitated via a surface admittance gTI, which significantly affects the phase speeds and the spatial profiles of the Dyakonov–Tamm waves. Most significantly, it is possible that a Dyakonov–Tamm wave propagates co-parallel to a vector u in the interface plane, but no Dyakonov–Tamm wave propagates anti-parallel to u. The left/right asymmetry, which vanishes for gTI = 0, is highly attractive for one-way on-chip optical communication

    The Interplay of Variants Near LEKR and CCNL1 and Social Stress in Relation to Birth Size

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    Background We previously identified via a genome wide association study variants near LEKR and CCNL1 and in the ADCY5 genes lead to lower birthweight. Here, we study the impact of these variants and social stress during pregnancy, defined as social adversity and neighborhood disparity, on infant birth size. We aimed to determine whether the addition of genetic variance magnified the observed associations. Methodology/Principal Findings We analyzed data from the Northern Finland Birth Cohort 1986 (n = 5369). Social adversity was defined by young maternal age (<20 years), low maternal education (<11 years), and/or single marital status. Neighborhood social disparity was assessed by discrepancy between neighborhoods relative to personal socio-economic status. These variables are indicative of social and socioeconomic stress, but also of biological risk. The adjusted multiple regression analysis showed smaller birth size in both infants of mothers who experienced social adversity (birthweight by −40.4 g, 95%CI −61.4, −19.5; birth length −0.14 cm, 95%CI −0.23, −0.05; head circumference −0.09 cm 95%CI −0.15, −0.02) and neighborhood disparity (birthweight −28.8 g, 95%CI −47.7, −10.0; birth length −0.12 cm, 95%CI −0.20, −0.05). The birthweight-lowering risk allele (SNP rs900400 near LEKR and CCNL1) magnified this association in an additive manner. However, likely due to sample size restriction, this association was not significant for the SNP rs9883204 in ADCY5. Birth size difference due to social stress was greater in the presence of birthweight-lowering alleles. Conclusions/Significance Social adversity, neighborhood disparity, and genetic variants have independent associations with infant birth size in the mutually adjusted analyses. If the newborn carried a risk allele rs900400 near LEKR/CCNL1, the impact of stress on birth size was stronger. These observations give support to the hypothesis that individuals with genetic or other biological risk are more vulnerable to environmental influences. Our study indicates the need for further research to understand the mechanisms by which genes impact individual vulnerability to environmental insults

    Missing Links: Referrer Behavior and Job Segregation

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    How does referral recruitment contribute to job segregation, and what can organizations do about it? Current theory on network effects in the labor market emphasizes the job-seeker perspective, focusing on the segregated nature of job-seekers’ information and contact networks, and leaves little role for organizational influence. But employee referrals are necessarily initiated from within a firm by referrers. We argue that referrer behavior is the missing link that can help organizations manage the segregating effects of referring. Adopting the referrer’s perspective of the process, we develop a computational model which integrates a set of empirically documented referrer behavior mechanisms gleaned from extant organizational case studies. Using this model, we compare the segregating effects of referring when these behaviors are inactive to the effects when the behaviors are active. We show that referrer behaviors substantially boost the segregating effects of referring. This impact of referrer behavior presents an opportunity for organizations. Contrary to popular wisdom, we show that organizational policies designed to influence referrer behaviors can mitigate most if not all of the segregating effects of referring

    Effects of Acute Cytomegalovirus Infection on Rat Islet Allograft Survival

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    Transplantation of pancreatic islets is a promising therapy for the treatment of type 1 diabetes mellitus. However, long-term islet graft survival rates are still unsatisfactory low. In this study we investigated the role of cytomegalovirus (CMV) in islet allograft failure. STZ-diabetic rats received an allogenic islet graft in combination with either an acute CMV infection or control infection. A third group received ganciclovir treatment in addition to the CMV infection. Graft function was assessed by measuring basal blood glucose levels. After sacrifice, the islet grafts were retrieved for analysis of infection and leukocyte infiltration. CMV-infected recipients demonstrated accelerated islet graft failure compared to noninfected controls. CMV infection of the graft was only observed prior to complete graft failure. Quantification of the leukocyte infiltration demonstrated increased CD8(+) T-cell and NK cell infiltration in the CMV-infected grafts compared to the controls. This suggests that CMV infection accelerates immune-mediated graft destruction. Antiviral ganciclovir treatment did not prevent accelerated graft failure, despite effectively decreasing the grade of infection. Our data confirm the recently published CITR data, which state that CMV is an independent risk factor for failure of islet grafts. Also, our data demonstrate that new approaches for preventing virus-induced islet allograft failure may be required
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