Fabrication and analogue applications of nanoSQUIDs using Dayem bridge junctions

We report here recent work at the U.K. National Physical Laboratory on developing nanoscale SQUIDs using Dayem bridge Josephson junctions. The advantages are simplicity of fabrication, exceptional low-noise performance, toward the quantum limit, and a range of novel applications. Focused ion beam patterned Nb SQUID, possessing exceptionally low noise (∼200 nΦ0/Hz1/2 above 1 kHz), and operating above 4.2 K can be applied to measurement of nanoscale magnetic objects or coupled to nanoelectromechanical resonators, as well as single particle detection of photons, protons, and ions. The limited operating temperature range may be extended by exposing the Dayem bridges to carefully controlled ion beam implantation, leading to nonreversible changes in junction transition temperature.The work reported here was supported in part by the EMRP projects ‘MetNEMS’ NEW-08 and ‘BioQUART’SIB-06. The EMRP is jointly funded by the EMRP participating countries within EURAMET and the European Union

Novel methods of fabrication and metrology of superconducting nanostructures

As metrology extends toward the nanoscale, a number of potential applications and new challenges arise. By combining photolithography with focused ion beam and/or electron beam methods, superconducting quantum interference devices (SQUIDs) with loop dimensions down to 200 nm and superconducting bridge dimensions of the order 80 nm have been produced. These SQUIDs have a range of potential applications. As an illustration, we describe a method for characterizing the effective area and the magnetic penetration depth of a structured superconducting thin film in the extreme limit, where the superconducting penetration depth $lambda$ is much greater than the film thickness and is comparable with the lateral dimensions of the device

Distinct functions of integrin alpha and beta subunit cytoplasmic domains in cell spreading and formation of focal adhesions.

Integrin-mediated cell adhesion often results in cell spreading and the formation of focal adhesions. We exploited the capacity of recombinant human alpha IIb beta 3 integrin to endow heterologous cells with the ability to adhere and spread on fibrinogen to study the role of integrin cytoplasmic domains in initiation of cell spreading and focal adhesions. The same constructs were also used to analyze the role of the cytoplasmic domains in maintenance of the fidelity of the integrin repertoire at focal adhesions. Truncation mutants of the cytoplasmic domain of alpha IIb did not interfere with the ability of alpha IIb beta 3 to initiate cell spreading and form focal adhesions. Nevertheless, deletion of the alpha IIb cytoplasmic domain allowed indiscriminate recruitment of alpha IIb beta 3 to focal adhesions formed by other integrins. Truncation of the beta 3 subunit cytoplasmic domain abolished cell spreading mediated by alpha IIb beta 3 and also abrogated recruitment of alpha IIb beta 3 to focal adhesions. This truncation also dramatically impaired the ability of alpha IIb beta 3 to mediate the contraction of fibrin gels. In contrast, the beta 3 subunit cytoplasmic truncation did not reduce the fibrinogen binding affinity of alpha IIb beta 3. Thus, the integrin beta 3 subunit cytoplasmic domain is necessary and sufficient for initiation of cell spreading and focal adhesion formation. Further, the beta 3 cytoplasmic domain is required for the transmission of intracellular contractile forces to fibrin gels. The alpha subunit cytoplasmic domain maintains the fidelity of recruitment of the integrins to focal adhesions and thus regulates their repertoire of integrins

The Facts of the Weather Extreme Events in the United States: Is there a Trend?

Numerous weather and climate extremes impact human society, the societal infrastructure, and the natural environment. The main purposes of this study were to review the historical record of weather extremes in the United States, identify the frequency and intensity of severe storms in the historical record, and examine the extent of economic damage resulting from those extreme events which occurred over the most recent decades. Potential changes in climate are forecast to result in possible frequency and/or intensity changes in extreme events, increases in precipitation, decreases in extreme low temperatures, increases in extreme high temperature, and changes in ecological systems such as climate-induced phonological shifts and possible biological extinctions. However, the impacts of tropical storms, hurricanes, and rainfalls on society and the nature systems need to be further investigated due to the difficulties of evaluations on variations of storms’ activities (intensity and frequency). Climatologists, biologists, and social scientists need to work together to bridge the gaps among the disciplines. Future research may consider focusing on future trends and changes in frequency of extreme events based on the outcomes of the most integrated climate models to evaluate the relationships between the severe weather extremes and the continued greenhouse gas scenarios of the coming decades

Effects of Climate Change in North America: An Overview

As forecast by many researchers, climate change can be expected to impact regions through direct effects (e.g., temperature shifts, changes in sea level, extreme weather events, and precipitation changes) and indirect effects (e.g., migrations of species and changes in ecosystems). Previous studies have reported how various regions will face challenges as to adaptations and vulnerabilities brought on by climate change differently according to their wealth. Interrelated impacts have been forecast to occur in North America stemming from variations due to climate change, including economic, ecological, environmental, and social impacts, as well as social and ecological changes. This study overviews the effects (direct and indirect) of climate change on various sectors in North America. It concludes, along with the suggestions of the AR4, that future studies should focus on regional studies of climate change, impacts of extreme weather events, and in-depth integrated models for mitigation, adaptation, and impact based on future simulations of climate change

Traffic agents for improving QoS in mixed infrastructure and ad hoc modes wireless LAN

As an important complement to infrastructured wireless networks, mobile ad hoc networks (MANET) are more flexible in providing wireless access services, but more difficult in meeting different quality of service (QoS) requirements for mobile customers. Both infrastructure and ad hoc network structures are supported in wireless local area networks (WLAN), which can offer high data-rate wireless multimedia services to the mobile stations (MSs) in a limited geographical area. For those out-of-coverage MSs, how to effectively connect them to the access point (AP) and provide QoS support is a challenging issue. By mixing the infrastructure and the ad hoc modes in WLAN, we propose in this paper a new coverage improvement scheme that can identify suitable idle MSs in good service zones as traffic agents (TAs) to relay traffic from those out-of-coverage MSs to the AP. The service coverage area of WLAN is then expanded. The QoS requirements (e.g., bandwidth) of those MSs are considered in the selection process of corresponding TAs. Mathematical analysis, verified by computer simulations, shows that the proposed TA scheme can effectively reduce blocking probability when traffic load is light

From Management to Sustainability: Strategies for Producers, Consumers, and Small Businesses; Journal: Journal of Management and Sustainability

The effects of climate change and other stressors on the agricultural sector provide proof that the need to achieve agricultural sustainability is a legitimate issue that should be addressed immediately. The ultimate financial benefits to achieving sustainability are immense. This study investigated the causes of climate change and reported how it directly and indirectly affects the agricultural sector of the Southeastern Region of the United States. We concluded that crops vary with the different adaptation strategies and with the predicted rise in temperature and fluctuation in precipitation. It is essential for producers to monitor closely their previous growing seasons. Long term investments include plant breeding, rotating crops, building infrastructure, and mitigation systems. Climate awareness and its impacts on agriculture by consumers, producers, and policymakers are essential to develop adaptation strategies to mitigate the effects of climate change

Can Walmart Integrate Values with Value?: From Sustainability to Sustainable Business

This article focuses on Walmart’s recent setbacks and how those setbacks provide an expanded role for product sustainability in Walmart’s business model. Walmart’s recent struggles are discussed and brief examples of their sustainable initiatives are given. Sustainability’s effect on consumer behavior is addressed. Consumer demand for and loyalty to green brands is one of the main reasons Walmart’s sustainability index could revive the company

Stress-related differential expression of multiple β-carotene ketolase genes in the unicellular green alga Haematococcus pluvialis

The unicellular green alga Haematococcus pluvialis is used as a biological production system for astaxanthin. It accumulates large amounts of this commercially interesting ketocarotenoid under a variety of environmental stresses. Here we report the identification and expression of three different β-carotene ketolase genes (bkt) that are involved in the biosynthesis of astaxanthin in a single strain of the alga. Bkt1 and bkt2 proved to be the crtO and bkt previously isolated from two different strains of H. pluvialis. Bkt3 is a novel third gene, which shared 95% identical nucleotide sequence with bkt2. Nitrogen deficiency alone could not induce the alga cells to produce astaxanthin in 3 days even though it enhances the expression of the bkt genes to three times of that in normal growing cells within 16 h. High light irradiation (125 μmol m -2 s -1) or 45 mM sodium acetate greatly increased the expression of bkt genes to 18 or 52 times of that in normal growing cells, resulting in an accumulation of substantial astaxanthin (about 6 mg g -1 dry biomass) in 3 days. It is suggested that the existence of the multiple bkt genes and their strong up-regulation by different stress conditions is one of the reasons that H. pluvialis accumulates large amounts of astaxanthin in an instant response to stress environments. © 2005 Elsevier B.V. All rights reserved.postprin

Effect of magnetic field on electron transport in HgTe/CdTe quantum wells: numerical analysis

The effect of magnetic field on electron transport in the inverted band structure of HgTe/CdTe quantum well is investigated. Although magnetic field breaks the time-reversal symmetry, the quantum spin Hall effect can still survive at large magnetic field up to 10 T. Moreover, two quantum anomalous Hall-like phases emerge, in which the system only has a spin-up or spin-down edge state at a given sample edge and the edge current is spin polarized. By tuning the Fermi energy, the system can transit between the quantum spin Hall phase and two quantum anomalous Hall-like phases, so the polarized direction of the edge current is well controllable. Thus the spin selectivity can be realized for potential applications of spintronics. Due to the quantum spin and anomalous Hall-like effects, the longitudinal and Hall resistances exhibit quantum plateaus. In addition, at certain magnetic field, some exotic plateaus like 23 fractional quantum Hall effect are also observed, where edge states with the same spin counterpropagate at the one edge. At last, these plateaus are hardly affected by Rashba spin-orbit interaction, Zeeman effect, and Anderson disorder. © 2012 American Physical Society.published_or_final_versio