229 research outputs found
Fermi surface and quasiparticle dynamics of Na(x)CoO2 {x=0.7} investigated by Angle-Resolved Photoemission Spectroscopy
We present an angle-resolved photoemission study of Na0.7CoO2, the host
cobaltate of the NaxCoO2.yH2O series. Our results show a large hexagonal-like
hole-type Fermi surface, an extremely narrow strongly renormalized
quasiparticle band and a small Fermi velocity. Along the Gamma to M high
symmetry line, the quasiparticle band crosses the Fermi level from M toward
Gamma consistent with a negative sign of effective single-particle hopping (t
): t is estimated to be about 8 meV which is on the order of exchange coupling
J in this system. This suggests that t ~ J ~ 10 meV is an important energy
scale in the system. Quasiparticles are well defined only in the T-linear
resistivity regime. Small single particle hopping and unconventional
quasiparticle dynamics may have implications for understanding the unusual
behavior of this new class of compounds.Comment: Revised text, Added Figs, Submitted to PR
Role of deep levels and interface states in the capacitance characteristics of allâsputtered CuInSe2/CdS solar cell heterojunctions
Allâsputtered CuInSe2/CdS solar cellheterojunctions have been analyzed by means of capacitanceâfrequency (CâF) and capacitanceâbias voltage (CâV) measurements. Depending on the CuInSe2 layer composition, two kinds of heterojunctions were analyzed: type 1 heterojunctions (based on stoichiometric or slightly Inârich CuInSe2 layers) and type 2 heterojunctions (based on Cuârich CuInSe2 layers). In type 1 heterojunctions, a 80âmeV donor level has been found. Densities of interface states in the range 101 0â101 1 cm2âeVâ 1 (type 1) and in the range 101 2â101 3 cmâ 2âeVâ 1 (type 2) have been deduced. On the other hand, doping concentrations of 1.6Ă101 6 cmâ 3 for stoichiometric CuInSe2 (type 1 heterojunction) and 8Ă101 7 cmâ 3 for the CdS (type 2 heterojunction) have been deduced from CâVmeasurements
Aspergillus niger: an unusual cause of invasive pulmonary aspergillosis
Infections due to Aspergillus species cause significant morbidity and mortality. Most are attributed to Aspergillus fumigatus, followed by Aspergillus flavus and Aspergillus terreus. Aspergillus niger is a mould that is rarely reported as a cause of pneumonia. A 72-year-old female with chronic obstructive pulmonary disease and temporal arteritis being treated with steroids long term presented with haemoptysis and pleuritic chest pain. Chest radiography revealed areas of heterogeneous consolidation with cavitation in the right upper lobe of the lung. Induced bacterial sputum cultures, and acid-fast smears and cultures were negative. Fungal sputum cultures grew A. niger. The patient clinically improved on a combination therapy of empiric antibacterials and voriconazole, followed by voriconazole monotherapy. After 4 weeks of voriconazole therapy, however, repeat chest computed tomography scanning showed a significant progression of the infection and near-complete necrosis of the right upper lobe of the lung. Serum voriconazole levels were lowânormal (1.0â
Îźg mlâ1, normal range for the assay 0.5â6.0âÎźg mlâ1). A. niger was again recovered from bronchoalveolar lavage specimens. A right upper lobectomy was performed, and lung tissue cultures grew A. niger. Furthermore, the lung histopathology showed acute and organizing pneumonia, fungal hyphae and oxalate crystallosis, confirming the diagnosis of invasive A. niger infection. A. niger, unlike A. fumigatus and A. flavus, is less commonly considered a cause of invasive aspergillosis (IA). The finding of calcium oxalate crystals in histopathology specimens is classic for A. niger infection and can be helpful in making a diagnosis even in the absence of conidia. Therapeutic drug monitoring may be useful in optimizing the treatment of IA given the wide variations in the oral bioavailability of voriconazole
Trisomy of a Down Syndrome Critical Region Globally Amplifies Transcription via HMGN1 Overexpression
Down syndrome (DS, trisomy 21) is associated with developmental abnormalities and increased leukemia risk. To reconcile chromatin alterations with transcriptome changes, we performed paired exogenous spike-in normalized RNA and chromatin immunoprecipitation sequencing in DS models. Absolute normalization unmasks global amplification of gene expression associated with trisomy 21. Overexpression of the nucleosome binding protein HMGN1 (encoded on chr21q22) recapitulates transcriptional changes seen with triplication of a Down syndrome critical region on distal chromosome 21, and HMGN1 is necessary for B cell phenotypes in DS models. Absolute exogenous-normalized chromatin immunoprecipitation sequencing (ChIP-Rx) also reveals a global increase in histone H3K27 acetylation caused by HMGN1. Transcriptional amplification downstream of HMGN1 is enriched for stage-specific programs of B cells and B cell acute lymphoblastic leukemia, dependent on the developmental cellular context. These data offer a mechanistic explanation for DS transcriptional patterns and suggest that further study of HMGN1 and RNA amplification in diverse DS phenotypes is warranted. How trisomy 21 contributes to Down syndrome phenotypes, including increased leukemia risk, is not well understood. Mowery et al. use per-cell normalization approaches to reveal global transcriptional amplification in Down syndrome models. HMGN1 overexpression is sufficient to induce these alterations and promotes lineage-associated transcriptional programs, signaling, and B cell progenitor phenotypes
The strategic calculus of terrorism: Substitution and competition in the IsraelâPalestine conflict
Previous work on the dynamics of conflicts where we see terrorism has tended to focus on whether we see shifts in attack mode following government countermeasures. We contend that many factors other than counterinsurgency can influence whether groups resort to terrorism, including competition between groups, as well as their relationship to public opinion and other political events. Hence, understanding terrorist tactics in prolonged conflicts with multiple actors requires us to consider a more general framework of innovation, imitation, competition and dependence between actors. We use disaggregated data on terrorist attacks, counterterrorism and public opinion in the IsraelâPalestine conflict to jointly evaluate predictions derived from several conventional theories of strategic behaviour. We find that the strategic calculus of Palestinian groups is complex and cannot be treated as time invariant. Our results suggest that factors such as the degree of public support, inter-group competition, the anticipation of countermeasures and non-trivial non-violent payoffs have an observable effect on the strategic behaviour of the Palestinian groups, and that structural relationships are often far from constant over time. </jats:p
Border collapse and boundary maintenance: militarisation and the micro-geographies of violence in IsraelâPalestine
This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.Drawing upon subaltern geopolitics and feminist geography, this article explores how militarisation shapes micro-geographies of violence and occupation in IsraelâPalestine. While accounts of spectacular and large-scale political violence dominate popular imaginaries and academic analyses in/of the region, a shift to the micro-scale foregrounds the relationship between power, politics and space at the level of everyday life. In the context of IsraelâPalestine, micro-geographies have revealed dynamic strategies for âgetting byâ or âdealing withâ the occupation, as practiced by Palestinian populations in the face of spatialised violence. However, this article considers how Jewish Israelis actively shape the spatial micro-politics of power within and along the borders of the Israeli state. Based on 12 months of ethnographic research in Tel Aviv and West Jerusalem during 2010â2011, an analysis of everyday narratives illustrates how relations of violence, occupation and domination rely upon gendered dynamics of border collapse and boundary maintenance. Here, the borders between home front and battlefield break down at the same time as communal boundaries are reproduced, generating conditions of âtotal militarismâ wherein military interests and agendas are both actively and passively diffused. Through gendering the militarised micro-geographies of violence among Jewish Israelis, this article reveals how individuals construct, navigate and regulate the everyday spaces of occupation, detailing more precisely how macro political power endures.This work was supported by the SOAS, University of London; University of London Central Research Fund
Recommended from our members
Foreign policy and globalization theory: The case of Israel
Since the early 1990s, international relations has witnessed a stimulating debate on globalization. This debate laid the foundations for globalization theory (GT), providing the tools for an empirical examination of the globalization of multiple activities: from politics and organized violence, to finance, trade and production, through culture and environmental degradation. However, examination of what appear to be the best-known works on globalization reveals that foreign policy has been virtually excluded from GT. In this context, based on what is described here as a synergistic transformationalist approach (STA) to globalization, I provide a critique of GT. The critique is geared towards examining why foreign policy hitherto has been overlooked by contemporary GT. I expose the problems this generates and address them by exploring how STA enables GT to incorporate foreign policy. I use the case of Israel heuristically to elicit how incorporating foreign policy into GT may provide a better understanding of the relationship between foreign policy and globalization. Three themes are highlighted: the role of foreign policy in inducing and reproducing globalization; determining the mutually constitutive relationship between globalization and the state; and shaping the interfacing between international politics and globalization
- âŚ