From Door to Desk(top): The Portal-to-Portal Act in the Digital Age

This note examines wage and hour litigation in the context of booting up and shutting down computers in call centers and the problem of analogizing physical work to digital work under the Fair Labor Standards Act. Pajda argues that by viewing computers as workplaces rather than tools for the purposes of determining whether booting up and shutting down computers are compensable workplace activities, courts can bypass the fact intensive inquiry on whether these actions are “integral and indispensable” to the work of the employee and provide clear guidelines to employers on what needs to be compensated. Pajda further argues that by analogizing computers to workplaces, employees and unions could bargain for contracts that circumscribe a default rule that booting up and shutting down computers is non-compensable

098— The Misrepresentation of Native American Women In The Media and Their Social Activism Against Violence and Mistreatment

This poster takes a look at the myths and stereotypes surrounding Native American women in media and throughout history. In this poster, we examine the work that Native American women have done in social movements such as #TakingBackTigerLilly and #NotYourMascot, that are working towards dispelling the stereotypes and false impressions surrounding them. This poster also examines the violence that native women are exposed to and their social activism through movements. These movements are meant to show people the truth about the violent acts that affect native women and their communities

PTH and arterial hypertension

Parathormon (PTH) jest od wielu lat postrzegany jako potencjalny czynnik hipertensynogenny. Pogląd ten opiera się jednak tylko na dowodach pośrednich, takich jak podwyższone stężenie PTH w surowicy u chorych z nadciśnieniem tętniczym pierwotnym oraz zwiększona częstość występowania nadciśnienia tętniczego u pacjentów z pierwotną nadczynnością przytarczyc (pHPT). Parenteralne podanie PTH powoduje krótkotrwały rozkurcz naczyń oraz wzrost natriurezy, co przemawia przeciwko udziałowi PTH w patogenezie nadciśnienia tętniczego. Wpływ PTH na ciśnienie tętnicze może być następstwem pogorszenia funkcji śródbłonka naczyń, proliferacji komórek mięśni gładkich naczyń oraz przerostu mięśnia sercowego. Wątpliwości dotyczące udziału PTH w etiopatogenezie nadciśnienia pierwotnego powstają przy uwzględnieniu czynności wydalniczej nerek, która często jest upośledzona nie tylko u chorych z pHPT, ale również u pacjentów z nadciśnieniem tętniczym związanym z nefropatią nadciśnieniową i starzeniem się organizmu. Należy więc zwrócić szczególną uwagę na niewątpliwy niekorzystny wpływ przewlekłej ekspozycji nerek na zwiększone stężenie PTH i wapnia w surowicy u pacjentów z pHPT. Niezależnie od nieudowodnionej roli PTH w etiopatogenezie nadciśnienia tętniczego, pHPT wiąże się niewątpliwie ze zwiększonym ryzykiem schorzeń sercowo-naczyniowych. Celem niniejszego, krytycznego przeglądu literatury jest przedstawienie aktualnego stanu wiedzy na temat zależności pomiędzy PTH a nadciśnieniem tętniczym.Parathormon (PTH) has been recognized as a potential factor in the etiopathogenesis of essential hypertension. The higher prevalence of arterial hypertention in primary hyperparathyroidism (pHPT) than in the general population and higher serum PTH concetration in patients with essential hypertensive are the only indirect evidence confirming this assumption. Infusion of PTH in man results in transient vasodilatation and increased urinary sodium excretion that gives evidence against its hypertensive effect. On the contrary, impaired endothelial function, proliferation of vascular smooth cells and heart hypertrophy may cause increase of blood pressure. Question concerning the role of PTH in the pathogenesis of arterial hypertension arises when excretory renal function, which is often impaired not only in patients with pHPT but also with arterial hypertension as a result of hypertensive nephropathy and ageing, is taken under consideration. It is important to remember about the negative consequences of long-term kidney exposition to increased PTH and serum calcium level in patients with pHPT. However, the role of PTH in the etiopathogenesis of arterial hypertension is still unclear, pHPT is undoubtedly associated with increased cardiovascular risk. The aim of this critical review is to summarize current arguments concerning the relationship between PTH and arterial hypertension

A new type of temperature driven reorientation transition in magnetic thin films

We present a new type of temperature driven spin reorientation transition (SRT) in thin films. It can occur when the lattice and the shape anisotropy favor different easy directions of the magnetization. Due to different temperature dependencies of the two contributions the effective anisotropy may change its sign and thus the direction of the magnetization as a function of temperature may change. Contrary to the well-known reorientation transition caused by competing surface and bulk anisotropy contributions the reorientation that we discuss is also found in film systems with a uniform lattice anisotropy. The results of our theoretical model study may have experimental relevance for film systems with positive lattice anisotropy, as e.g. thin iron films grown on copper.Comment: 7 pages, 4 figures, accepted for publication in EPJ

Finite size effects with variable range exchange coupling in thin-film Pd/Fe/Pd trilayers

The magnetic properties of thin-film Pd/Fe/Pd trilayers in which an embedded ~1.5 A-thick ultrathin layer of Fe induces ferromagnetism in the surrounding Pd have been investigated. The thickness of the ferromagnetic trilayer is controlled by varying the thickness of the top Pd layer over a range from 8 A to 56 A. As the thickness of the top Pd layer decreases, or equivalently as the embedded Fe layer moves closer to the top surface, the saturated magnetization normalized to area and the Curie temperature decrease whereas the coercivity increases. These thickness-dependent observations for proximity-polarized thin-film Pd are qualitatively consistent with finite size effects that are well known for regular thin-film ferromagnets. The critical exponent $\beta$ of the order parameter (magnetization) is found to approach the mean field value of 0.5 as the thickness of the top Pd layer increases. The functional forms for the thickness dependences, which are strongly modified by the nonuniform exchange interaction in the polarized Pd, provide important new insights to understanding nanomagnetism in two-dimensions.Comment: 14 pages, 5 figures, submitted to JMM

Exchange coupling in transition-metal nano-clusters on Cu(001) and Cu(111) surfaces

We present results of density-functional calculations on the magnetic properties of Cr, Mn, Fe and Co nano-clusters (1 to 9 atoms large) supported on Cu(001) and Cu(111). The inter-atomic exchange coupling is found to depend on competing mechanisms, namely ferromagnetic double exchange and antiferromagnetic kinetic exchange. Hybridization-induced broadening of the resonances is shown to be important for the coupling strength. The cluster shape is found to weaken the coupling via a mechanism that comprises the different orientation of the atomic d-orbitals and the strength of nearest-neighbour hopping. Especially in Fe clusters, a correlation of binding energy and exchange coupling is also revealed

Exchange interactions and Curie temperature in (GaMn)As

We use supercell and frozen-magnon approaches to study the dependence of the magnetic interactions in (Ga,Mn)As on the Mn concentration. We report the parameters of the exchange interaction between Mn spins and the estimates of the Curie temperature within the mean-field and random-phase approximations. In agreement with experiment we obtain a nonmonotonous dependence of the Curie temperature on the Mn concentration. We estimate the dependence of the Curie temperature on the concentration of the carries in the system and show that the decrease of the number of holes in the valence band leads to fast decrease of the Curie temperature. We show that the hole states of the valence band are more efficient in mediating the exchange interaction between Mn spins than the electron states of the conduction band

Electronic structure, exchange interactions and Curie temperature in diluted III-V magnetic semiconductors: (GaCr)As, (GaMn)As, (GaFe)As

We complete our earlier (Phys. Rev. B, {\bf 66}, 134435 (2002)) study of the electronic structure, exchange interactions and Curie temperature in (GaMn)As and extend the study to two other diluted magnetic semiconductors (GaCr)As and (GaFe)As. Four concentrations of the 3d impurities are studied: 25%, 12.5%, 6.25%, 3.125%. (GaCr)As and (GaMn)As are found to possess a number of similar features. Both are semi-metallic and ferromagnetic, with similar properties of the interatomic exchange interactions and the same scale of the Curie temperature. In both systems the presence of the charge carriers is crucial for establishing the ferromagnetic order. An important difference between two systems is in the character of the dependence on the variation of the number of carriers. The ferromagnetism in (GaMn)As is found to be very sensitive to the presence of the donor defects, like As$_{\rm Ga}$ antisites. On the other hand, the Curie temperature of (GaCr)As depends rather weakly on the presence of this type of defects but decreases strongly with decreasing number of electrons. We find the exchange interactions between 3d atoms that make a major contribution into the ferromagnetism of (GaCr)As and (GaMn)As and propose an exchange path responsible for these interactions. The properties of (GaFe)As are found to differ crucially from the properties of (GaCr)As and (GaMn)As. (GaFe)As does not show a trend to ferromagnetism and is not half-metallic that makes this system unsuitable for the use in spintronic semiconductor devices

Exchange coupling in Eu monochalcogenides from first principles

Using a density functional method with explicit account for strong Coulomb repulsion within the 4f shell, we calculate effective exchange parameters and the corresponding ordering temperatures of the (ferro)magnetic insulating Eu monochalcogenides (EuX; X=O,S,Se,Te) at ambient and elevated pressure conditions. Our results provide quantitative account of the many-fold increase of the Curie temperatures with applied pressure and reproduce well the enhancement of the tendency toward ferromagnetic ordering across the series from telluride to oxide, including the crossover from antiferromagnetic to ferromagnetic ordering under pressure in EuTe and EuSe. The first and second neighbor effective exchange are shown to follow different functional dependencies. Finally, model calculations indicate a significant contribution of virtual processes involving the unoccupied f states to the effective exchange.Comment: 4 pages, 6 figure