Origin of the butterfly magnetoresistance in a Dirac nodal-line system

We report a study on the magnetotransport properties and on the Fermi surfaces (FS) of the ZrSi(Se,Te) semimetals. Density Functional Theory (DFT) calculations, in absence of spin orbit coupling (SOC), reveal that both the Se and the Te compounds display Dirac nodal lines (DNL) close to the Fermi level $\varepsilon_F$ at symmorphic and non-symmorphic positions, respectively. We find that the geometry of their FSs agrees well with DFT predictions. ZrSiSe displays low residual resistivities, pronounced magnetoresistivity, high carrier mobilities, and a butterfly-like angle-dependent magnetoresistivity (AMR), although its DNL is not protected against gap opening. As in Cd$_3$As$_2$, its transport lifetime is found to be 10$^2$ to 10$^3$ times larger than its quantum one. ZrSiTe, which possesses a protected DNL, displays conventional transport properties. Our evaluation indicates that both compounds most likely are topologically trivial. Nearly angle-independent effective masses with strong angle dependent quantum lifetimes lead to the butterfly AMR in ZrSiSe

Transnational Legal Practice 2008

The current financial turmoil shaking the world illustrates the connectedness of national markets and economies. Legal practice is no exception: lawyers and their firms are experiencing the upheaval along with their clients.1 This has resulted in new opportunities for lawyers and firms–in bankruptcy and restructuring and, likely in the future, in regulatory advising as well–and, at the same time, in substantial challenges. The promise of benefits from a diversified practice–in terms of both substance and geography–is being tested as lawyers and law firms follow their clients through the uncertainties of the current economic conditions. As law firms cut the size of their legal and non-legal staffs and decrease compensation expectations, they also are capitalizing on the benefits of a geographically diverse footprint of practice by looking to overseas activities as opportunities for growth. The number of firms announcing new offices in the Middle East, for example, has not slowed during the economic crisis.2 Over the last twenty years or so, the growth of overseas activities of the largest U.S.-based law firms has far outpaced their growth within the United States, by a rate of ten-to-one.3 In 2007, more than 15,000 lawyers worked for the National Law Journal 250 firms in more than 550 offices located outside the United States.4 Indeed, two U.S.-based law firms with substantial investments in overseas offices joined the ranks of four of the London “Magic Circle” firms in a new category dubbed the “global elite.”5 But the description so far relates only to the most visible part of the story of the importance of overseas-related work for U.S. lawyers. Overseas-related work also supports lawyers working for firms that do not have formal international footprints. These may be firms with foreign clients or U.S.-based clients involved in offshore activities or partnerships. They may be firms that are members of international networks or associations of lawyers that serve as a source of referral relationships, among other things. Each of these arrangements points to the continuing importance of keeping watch over the regulatory and business environment for lawyers outside the United States. The U.S. Department of Commerce Bureau of Economic Analysis estimates that the export of U.S. legal services generated $6.4 billion in receipts in 2007, while imports of legal services were valued at nearly$1.6 billion, yielding a four-to-one surplus for balance-of-payment accounts.6 If globalization continues, as appears likely, lawyers may be able to rely on overseas activities as a sort of hedge against instability at home. Access to overseas legal markets, then, remains an issue of high priority

Transnational Legal Practice 2008

The current financial turmoil shaking the world illustrates the connectedness of national markets and economies. Legal practice is no exception: lawyers and their firms are experiencing the upheaval along with their clients.1 This has resulted in new opportunities for lawyers and firms–in bankruptcy and restructuring and, likely in the future, in regulatory advising as well–and, at the same time, in substantial challenges. The promise of benefits from a diversified practice–in terms of both substance and geography–is being tested as lawyers and law firms follow their clients through the uncertainties of the current economic conditions. As law firms cut the size of their legal and non-legal staffs and decrease compensation expectations, they also are capitalizing on the benefits of a geographically diverse footprint of practice by looking to overseas activities as opportunities for growth. The number of firms announcing new offices in the Middle East, for example, has not slowed during the economic crisis.2 Over the last twenty years or so, the growth of overseas activities of the largest U.S.-based law firms has far outpaced their growth within the United States, by a rate of ten-to-one.3 In 2007, more than 15,000 lawyers worked for the National Law Journal 250 firms in more than 550 offices located outside the United States.4 Indeed, two U.S.-based law firms with substantial investments in overseas offices joined the ranks of four of the London “Magic Circle” firms in a new category dubbed the “global elite.”5 But the description so far relates only to the most visible part of the story of the importance of overseas-related work for U.S. lawyers. Overseas-related work also supports lawyers working for firms that do not have formal international footprints. These may be firms with foreign clients or U.S.-based clients involved in offshore activities or partnerships. They may be firms that are members of international networks or associations of lawyers that serve as a source of referral relationships, among other things. Each of these arrangements points to the continuing importance of keeping watch over the regulatory and business environment for lawyers outside the United States. The U.S. Department of Commerce Bureau of Economic Analysis estimates that the export of U.S. legal services generated $6.4 billion in receipts in 2007, while imports of legal services were valued at nearly$1.6 billion, yielding a four-to-one surplus for balance-of-payment accounts.6 If globalization continues, as appears likely, lawyers may be able to rely on overseas activities as a sort of hedge against instability at home. Access to overseas legal markets, then, remains an issue of high priority

Evolution of Structural and Physical Properties of Sr3(Ru1-xMnx)2O7 with Mn Concentration

Layered ruthenates are prototype materials with strong structure-property correlations. We report the structural and physical properties of double-layered perovskite Sr3(Ru1-xMnx)2O7 single crystals with 0<=x<=0.7. Single crystal x-ray diffraction refinements reveal that Mn doping on the Ru site leads to the shrinkage of unit-cell volume and disappearance of (Ru/Mn)O6 octahedron rotation when x>0.16, while the crystal structure remains tetragonal. Correspondingly, the electric and magnetic properties change with x. The electrical resistivity reveals metallic character (d rho/d T>0) at high temperatures but insulating behavior (d rho/d T<0) below a characteristic temperature T_MIT. Interestingly, T_MIT is different from T_M, at which magnetic susceptibility reaches maximum. T_MIT monotonically increases with increasing x while T_M shows non-monotonic dependence with x. The difference between T_MIT and T_M (T_MIT>T_M) becomes larger when x>0.16. The constructed phase diagram consists of five distinct regions, demonstrating that the physical properties of such a system can easily be tuned by chemical doping.Comment: 5 pages, 4 figure

CXCR7 influences leukocyte entry into the CNS parenchyma by controlling abluminal CXCL12 abundance during autoimmunity

During CNS autoimmunity, brain endothelial cell CXCR7 internalizes CXCL12 from the perivascular space, thereby permitting leukocyte migration into the CNS parenchyma

Enhanced sphingosine-1-phosphate receptor 2 expression underlies female CNS autoimmunity susceptibility

Multiple sclerosis (MS) is an inflammatory disease of the CNS that is characterized by BBB dysfunction and has a much higher incidence in females. Compared with other strains of mice, EAE in the SJL mouse strain models multiple features of MS, including an enhanced sensitivity of female mice to disease; however, the molecular mechanisms that underlie the sex- and strain-dependent differences in disease susceptibility have not been described. We identified sphingosine-1-phosphate receptor 2 (S1PR2) as a sex- and strain-specific, disease-modifying molecule that regulates BBB permeability by destabilizing adherens junctions. S1PR2 expression was increased in disease-susceptible regions of the CNS of both female SJL EAE mice and female patients with MS compared with their male counterparts. Pharmacological blockade or lack of S1PR2 signaling decreased EAE disease severity as the result of enhanced endothelial barrier function. Enhanced S1PR2 signaling in an in vitro BBB model altered adherens junction formation via activation of Rho/ROCK, CDC42, and caveolin endocytosis-dependent pathways, resulting in loss of apicobasal polarity and relocation of abluminal CXCL12 to vessel lumina. Furthermore, S1PR2-dependent BBB disruption and CXCL12 relocation were observed in vivo. These results identify a link between S1PR2 signaling and BBB polarity and implicate S1PR2 in sex-specific patterns of disease during CNS autoimmunity

Polycrystalline thin film materials and devices

Results of Phase II of a research program on polycrystalline thin film heterojunction solar cells are presented. Relations between processing, materials properties and device performance were studied. The analysis of these solar cells explains how minority carrier recombination at the interface and at grain boundaries can be reduced by doping of windows and absorber layers, such as in high efficiency CdTe and CuInSe{sub 2} based solar cells. The additional geometric dimension introduced by the polycrystallinity must be taken into consideration. The solar cells are limited by the diode current, caused by recombination in the space charge region. J-V characteristics of CuInSe{sub 2}/(CdZn)S cells were analyzed. Current-voltage and spectral response measurements were also made on high efficiency CdTe/CdS thin film solar cells prepared by vacuum evaporation. Cu-In bilayers were reacted with Se and H{sub 2}Se gas to form CuInSe{sub 2} films; the reaction pathways and the precursor were studied. Several approaches to fabrication of these thin film solar cells in a superstrate configuration were explored. A self-consistent picture of the effects of processing on the evolution of CdTe cells was developed

The Quantity Theory of Money is Valid. The New Keynesians are Wrong!

We test the quantity theory of money (QTM) using a novel approach and a large new sample. We do not follow the usual approach of first differentiating the logarithm of the Cambridge equation to obtain an equation relating the growth rate of real GDP, the growth rate of money and inflation. These variables must then again be ‘integrated’ by averaging in order to obtain stable relationships. Instead we suggest a much simpler procedure for testing directly the stability of the coefficient of the Cambridge equation. For 125 countries and post-war data we find the coefficient to be surprisingly stable. We do not select for high inflation episodes as was done in most empirical studies; inflation rates do not even appear in our data set. Much work supporting the QTM has been done by economic historians and at the University of Chicago by Milton Friedman and his associates. The QTM was a foundation stone of the monetarist revolution. Subsequently belief in it waned. The currently dominant New Keynesian School, implicitly or explicitly denies the validity of the QTM. We survey this history and argue that the QTM is valid and New Keynesians are wrong