Switching of the magnetic order in CeRhIn5−x_{5-x}Snx_{x} in the vicinity of its quantum critical point

We report neutron diffraction experiments performed in the tetragonal antiferromagnetic heavy fermion system CeRhIn$_{5-x}$Sn$_{x}$ in its ($x$, $T$) phase diagram up to the vicinity of the critical concentration $x_c$ $\approx$ 0.40, where long range magnetic order is suppressed. The propagation vector of the magnetic structure is found to be $\bf{k_{IC}}$=(1/2, 1/2, $k_l$) with $k_l$ increasing from $k_l$=0.298 to $k_l$=0.410 when $x$ increases from $x$=0 to $x$=0.26. Surprisingly, for $x$=0.30, the order has changed drastically and a commensurate antiferromagnetism with $\bf{k_{C}}$=(1/2, 1/2, 0) is found. This concentration is located in the proximity of the quantum critical point where superconductivity is expected.Comment: 5 pages, 5 figures, submitted to Phys. Rev.

Entry pathways of herpes simplex virus type 1 into human keratinocytes are dynamin- and cholesterol-dependent

Herpes simplex virus type 1 (HSV-1) can enter cells via endocytic pathways or direct fusion at the plasma membrane depending on the cell line and receptor(s). Most studies into virus entry have used cultured fibroblasts but since keratinocytes represent the primary entry site for HSV-1 infection in its human host, we initiated studies to characterize the entry pathway of HSV-1 into human keratinocytes. Electron microscopy studies visualized free capsids in the cytoplasm and enveloped virus particles in vesicles suggesting viral uptake both by direct fusion at the plasma membrane and by endocytic vesicles. The ratio of the two entry modes differed in primary human keratinocytes and in the keratinocyte cell line HaCaT. Inhibitor studies further support a role for endocytosis during HSV-1 entry. Infection was inhibited by the cholesterol-sequestering drug methyl-beta-cyclodextrin, which demonstrates the requirement for host cholesterol during virus entry. Since the dynamin-specific inhibitor dynasore and overexpression of a dominant-negative dynamin mutant blocked infection, we conclude that the entry pathways into keratinocytes are dynamin-mediated. Electron microscopy studies confirmed that virus uptake is completely blocked when the GTPase activity of dynamin is inhibited. Ex vivo infection of murine epidermis that was treated with dynasore further supports the essential role of dynamin during entry into the epithelium. Thus, we conclude that HSV-1 can enter human keratinocytes by alternative entry pathways that require dynamin and host cholesterol

Phase diagram of CeVSb3 under pressure and its dependence on pressure conditions

We present temperature dependent resistivity and ac-calorimetry measurements of CeVSb3 under pressure up to 8 GPa in a Bridgman anvil cell modified to use a liquid medium and in a diamond anvil cell using argon as a pressure medium, respectively. We observe an initial increase of the ferromagnetic transition temperature Tc with pressures up to 4.5 GPa, followed by decrease of Tc on further increase of pressure and finally its disappearance, in agreement with the Doniach model. We infer a ferromagnetic quantum critical point around 7 GPa under hydrostatic pressure conditions from the extrapolation to 0 K of Tc and the maximum of the A coefficient from low temperature fits of the resistivity \rho (T)=\rho_{0}+AT^{n}. No superconductivity under pressure was observed down to 0.35 K for this compound. In addition, differences in the Tc(P) behavior when a slight uniaxial component is present are noticed and discussed and correlated to choice of pressure medium

Middle Atlantic Outer Continental Shelf Environmental Studies Volume 1: Executive Summary

Increasing demand for petroleum and natural gas in the United States has led to a need for development of reliable new domestic sources. The Outer Continental Shelf of the United States holds great interest among the oil companies for possible exploration and development of oil and gas resources to meet this need. This interest was demonstrated for the Middle Atlantic Outer Continental Shelf in the oil companies\u27 response to the lease sale conducted in August 1976. Of the 154 tracts comprising 876,750 acres offered for lease in August 1975 for exploratory drilling in the Baltimore Canyon Trough (Figure 1), oil compa~ies purchased drilling rights to 101 tracts comprising 575,011 acres. The Bureau of Land Management Environmental Studies Program was established to provide information needed for prediction, assessment, and management of impacts on the human marine and coastal environments of the Outer Continental Shelf and the nearshore area which may be affected by these drilling activities. The studies are designed to: 1. Provide information on the status of the environment upon which the prediction of the impacts of Outer Continental Shelf oil and gas development for leasing decisionmaking may be based, 2. provide information on the ways and extent that Outer Continental Shelf development can potentially impact the human, marine, biological, and coastal areas, 3. ensure that information already available or being collected under the program is in a form that can be used in the decisionmaking process associated with a specific leasing action or with the longer term Outer Continental Shelf minerals management responsibilities, and 4. provide a basis for furture monitoring of Outer Continental Shelf operations

Similarity of Fermi Surface in the Hidden Order State and in the Antiferromagnetic State of URu2Si2

Shubnikov-de Haas measurements of high quality URu2Si2 single crystals reveal two previously unobserved Fermi surface branches in the so-called hidden order phase. Therefore about 55% of the enhanced mass is now detected. Under pressure in the antiferromagnetic state, the Shubnikov-de Haas frequencies for magnetic fields applied along the crystalline c axis show little change compared with the zero pressure data. This implies a similar Fermi surface in both the hidden order and antiferromagnetic states, which strongly suggests that the lattice doubling in the antiferromagnetic phase due to the ordering vector QAF = (0 0 1) already occurs in the hidden order. These measurements provide a good test for existing or future theories of the hidden order parameter.Comment: 4 pages, 4 figure

Thermal Storage with Ice Harvesting Systems

Application of Harvesting Ice Storage Systems. Thermal storage systems are becoming widely accepted techniques for utility load management. This paper discusses the principles of ice harvesting equipment and their application to the multi-use environments. The potential for application of low dew point environments in terms of comfort and system energy consumption will also be discussed. Several case studies will be the installations of harvesting thermal storage systems

Optimal Control of Harvesting Ice Thermal Storage Systems

Thermal storage is becoming a standard consideration in HVAC and process cooling systems. As the technology is refined, more attention is being given to minimize the energy consumption and power demand requirements. This paper addresses a method for optimal control of a harvesting ice storage system. A simplified procedure is used to develop 24 hour load data. Example installations will be shown

Antiferromagnetism and Superconductivity in CeRhIn5_5

We discuss recent results on the heavy fermion superconductor CeRhIn$_5$ which presents ideal conditions to study the strong coupling between the suppression of antiferromagnetic order and the appearance of unconventional superconductivity. The appearance of superconductivity as function of pressure is strongly connected to the suppression of the magnetic order. Under magnetic field, the re-entrance of magnetic order inside the superconducting state shows that antiferromagnetism nucleates in the vortex cores. The suppression of antiferromagnetism in CeRhIn$_5$ by Sn doping is compared to that under hydrostatic pressure.Comment: 6 pages, 8 figures, to be published in Proc. Int. Conf. Heavy Electrons (ICHE2010) J. Phys. Soc. Jpn. 80 (2011

Suppression of hidden order in URu2Si2 under pressure and restoration in magnetic field

We describe here recent inelastic neutron scattering experiments on the heavy fermion compound URu2Si2 realized in order to clarify the nature of the hidden order (HO) phase which occurs below T_0 = 17.5 K at ambient pressure. The choice was to measure at a given pressure P where the system will go, by lowering the temperature, successively from paramagnetic (PM) to HO and then to antiferromagnetic phase (AF). Furthermore, in order to verify the selection of the pressure, a macroscopic detection of the phase transitions was also achieved in situ via its thermal expansion response detected by a strain gauge glued on the crystal. Just above P_x = 0.5 GPa, where the ground state switches from HO to AF, the Q_0 = (1, 0, 0) excitation disappears while the excitation at the incommensurate wavevector Q_1 = (1.4, 0, 0) remains. Thus, the Q_0 = (1, 0, 0) excitation is intrinsic only in the HO phase. This result is reinforced by studies where now pressure and magnetic field $H$ can be used as tuning variable. Above P_x, the AF phase at low temperature is destroyed by a magnetic field larger than H_AF (collapse of the AF Q_0 = (1, 0, 0) Bragg reflection). The field reentrance of the HO phase is demonstrated by the reappearance of its characteristic Q_0 = (1, 0, 0) excitation. The recovery of a PM phase will only be achieved far above H_AF at H_M approx 35 T. To determine the P-H-T phase diagram of URu2Si2, macroscopic measurements of the thermal expansion were realized with a strain gauge. The reentrant magnetic field increases strongly with pressure. Finally, to investigate the interplay between superconductivity (SC) and spin dynamics, new inelastic neutron scattering experiments are reported down to 0.4 K, far below the superconducting critical temperature T_SC approx 1.3 K as measured on our crystal by diamagnetic shielding.Comment: 5 pages, 7 figures, ICN 2009 conference proceeding