645 research outputs found
Electronic properties of the pseudogap system (TaSe4)2I
The room temperature ``metallic'' properties of the quasi-one-dimensional
charge density wave system (TaSe4)2I differ markedly from those expected of
either a Fermi or a Luttinger Liquid. We discuss evidence for the simplest
possible explanation of the observed behavior of (TaSe4)2I in its conducting
phase - namely the existence of large quasi-static fluctuations of structural
order, which however remain of finite extent above the charge density wave
transition temperature. These fluctuations produce a pseudogap in the density
of states. We compute the temperature dependence of the optical and DC
conductivities of (TaSe4)2I in its conducting phase, the nature of its core
hole spectra, and the NMR relaxation rate. Predictions for these quantities are
made on the basis of a Lee, Rice and Anderson model. This model represents the
simplest theory of a pseudogap, and gives satisfactory agreement with
experiment in the cases where comparisons can be made. In contrast, the
predictions of a strongly correlated (Luttinger Liquid) model appear to to
contradict the data. The chief remaining discrepancy is that the gap appearing
in transport quantities is less than that observed in photoemission. We discuss
some possibilities for resolving this issue.Comment: 41 pages latex, 11 ps figures, uses IOP macro
Expansion of the ligand knowledge base for chelating P,P-donor ligands (LKB-PP)
[Image: see text] We have expanded the ligand knowledge base for bidentate P,P- and P,N-donor ligands (LKB-PP, Organometallics2008, 27, 1372–1383) by 208 ligands and introduced an additional steric descriptor (nHe(8)). This expanded knowledge base now captures information on 334 bidentate ligands and has been processed with principal component analysis (PCA) of the descriptors to produce a detailed map of bidentate ligand space, which better captures ligand variation and has been used for the analysis of ligand properties
Polyvalent diazonium polymers provide efficient protection of oncolytic adenovirus Enadenotucirev from neutralising antibodies while maintaining biological activity in vitro and in vivo
Oncolytic viruses offer many advantages for cancer therapy when administered directly to confined solid tumors. However, the systemic delivery of these viruses is problematic due to host immune response, undesired interactions with blood components and inherent targeting to the liver. Efficacy of systemically administered viruses has been improved by masking viral surface proteins with polymeric materials, through modulation of viral pharmacokinetic profile and accumulation in tumors in vivo. Here we describe a new class of polyvalent reactive based upon poly(N-(2-hydroxypropyl)methacrylamide) (polyHPMA) with diazonium reactive groups and their application in the modification of the chimeric oncolytic virus Enadenotucirev (EnAd). A series of six reactive copolymers with different chain lengths and density of reactive groups was synthesised and used to coat EnAd. Polymer coating was found to be extremely efficient with concentrations as low as 1 mg/mL resulting in complete (>99%) ablation of neutralising antibody binding. Coating efficiency was found to be dependent on both chain length and reactive group density. Coated viruses were found to have reduced transfection activity both in vitro and in vivo with greater protection against neutralising antibodies resulting in lower transgene production. However, in the presence of neutralising antibodies some in vivo transgene expression was maintained for coated virus compared to the uncoated control. Reduction in transgene expression was found to not be solely due to reduced cellular uptake but due to reducing unpackaging of the virus within the cells and reducing replication indicating that polymer coating does not cause permanent inactivation of the virus. These data suggest that virus activity may be modulated by appropriate design of coating polymers while retaining protection against neutralising antibodies
Does shear wave ultrasound independently predict axillary lymph node metastasis in women with invasive breast cancer?
Shear wave elastography (SWE) shows promise as an adjunct to greyscale ultrasound examination in assessing breast masses. In breast cancer, higher lesion stiffness on SWE has been shown to be associated with features of poor prognosis. The purpose of this study was to assess whether lesion stiffness at SWE is an independent predictor of lymph node involvement. Patients with invasive breast cancer treated by primary surgery, who had undergone SWE examination were eligible. Data were retrospectively analysed from 396 consecutive patients. The mean stiffness values were obtained using the Aixplorer(®) ultrasound machine from SuperSonic Imagine Ltd. Measurements were taken from a region of interest positioned over the stiffest part of the abnormality. The average of the mean stiffness value obtained from each of two orthogonal image planes was used for analysis. Associations between lymph node involvement and mean lesion stiffness, invasive cancer size, histologic grade, tumour type, ER expression, HER-2 status and vascular invasion were assessed using univariate and multivariate logistic regression. At univariate analysis, invasive size, histologic grade, HER-2 status, vascular invasion, tumour type and mean stiffness were significantly associated with nodal involvement. Nodal involvement rates ranged from 7 % for tumours with mean stiffness <50 kPa to 41 % for tumours with a mean stiffness of >150 kPa. At multivariate analysis, invasive size, tumour type, vascular invasion, and mean stiffness maintained independent significance. Mean stiffness at SWE is an independent predictor of lymph node metastasis and thus can confer prognostic information additional to that provided by conventional preoperative tumour assessment and staging
Differential p53 protein expression in breast cancer fine needle aspirates: the potential for in vivo monitoring
Fine needle aspiration (FNA) biopsy is the least invasive method of sampling breast cancer in vivo and provides material for breast cancer diagnosis. FNA has also been used to examine cellular markers to predict and monitor the effects of therapy. The aim of this study was to assess the accuracy of using FNA material compared with resected cancer for Western blotting studies of the p53 pathway, a key to tumour response to radiotherapy and chemotherapy. Paired samples of breast cancer FNAs collected pre-operatively and post-operatively were compared with tissue samples obtained at the time of surgical resection. Western blots were probed for p53 using the antibodies DO12 and DO1, and for levels of downstream proteins p21/WAF1 and p27. The protein extracted by FNA was sufficient for up to 5 Western blot studies. p53 expression and phosphorylation did not differ significantly pre- and post-operatively, indicating that intra-operative manipulation does not affect p53 expression or downstream activation in breast cancer. However, expression of p53, p21 and p27 varied between individual patients suggesting a range of p53 pathway activation in breast cancer. Immunohistochemistry confirmed that the cancer cells accounted for the protein expression detected on Western blots. FNA yields adequate protein for Western blotting studies and could be used as a method to monitor p53 activity in vivo before and during anti-cancer treatment possibly providing early evidence of tumour response to therapy. © 2001 Cancer Research Campaign http://www.bjcancer.co
Doing ‘judgemental rationality’ in empirical research: the importance of depth-reflexivity when researching in prison
Critical realist thought has theorised convincingly that epistemic relativism is constellationally embedded in ontological realism which in turn necessitates judgemental rationality. In social science, judgemental rationality involves acting upon plausible decisions about competing points of view. However, the tools for doing this are, as yet, under-articulated. This paper addresses this absence by articulating triangulation and depth-reflexivity as two tools for doing judgemental rationality in empirical research. It draws on the experiences of a diverse team working on an international comparative research project on conversion to Islam in prisons. It demonstrates how epistemic and relational gaps between researchers and research subjects can be bridged by mobilising the ‘laminated’ properties and personal attributes of a diverse research team that factors in attributes that are absent as well as those present. The biographical experiences of the team are analyzed in a variety of intersecting dimensions: faith, ethnicity/ethno-culture, gender, class and professionality
Pathways to diagnosis of non-small cell lung cancer: a descriptive cohort study
© 2019, Crown. Little has been published on the diagnostic and referral pathway for lung cancer in Australia. This study set out to quantify general practitioner (GP) and lung specialist attendance and diagnostic imaging in the lead-up to a diagnosis of non-small cell lung cancer (NSCLC) and identify common pathways to diagnosis in New South Wales (NSW), Australia. We used linked health data for participants of the 45 and Up Study (a NSW population-based cohort study) diagnosed with NSCLC between 2006 and 2012. Our main outcome measures were GP and specialist attendances, X-rays and computed tomography (CT) scans of the chest and lung cancer-related hospital admissions. Among our study cohort (N = 894), 60% (n = 536) had ≥4 GP attendances in the 3 months prior to diagnosis of NSCLC, 56% (n = 505) had GP-ordered imaging (chest X-ray or CT scan), 39% (N = 349) attended a respiratory physician and 11% (N = 102) attended a cardiothoracic surgeon. The two most common pathways to diagnosis, accounting for one in three people, included GP and lung specialist (respiratory physician or cardiothoracic surgeon) involvement. Overall, 25% of people (n = 223) had an emergency hospital admission. For 14% of people (N = 129), an emergency hospital admission was the only event identified on the pathway to diagnosis. We found little effect of remoteness of residence on access to services. This study identified a substantial proportion of people with NSCLC being diagnosed in an emergency setting. Further research is needed to establish whether there were barriers to the timely diagnosis of these cases
HLA Immunogenotype Determines Persistent Human Papillomavirus Virus Infection in HIV-Infected Patients Receiving Antiretroviral Treatment
A proportion of human immunodeficiency virus (HIV)–infected patients develop persistent, stigmatizing human papillomavirus (HPV)–related cutaneous and genital warts and anogenital (pre)cancer. This is the first study to investigate immunogenetic variations that might account for HPV susceptibility and the largest to date to categorize the HPV types associated with cutaneous warts in HIV-positive patients. The HLA class I and II allele distribution was analyzed in 49 antiretroviral (ART)–treated HIV-positive patients with persistent warts, 42 noninfected controls, and 46 HIV-positive controls. The allele HLA-B*44 was more frequently identified in HIV-positive patients with warts (P = .004); a susceptible haplotype (HLA-B*44, HLA-C*05; P = .001) and protective genes (HLA-DQB1*06; P = .03) may also contribute. Cutaneous wart biopsy specimens from HIV-positive patients harbored common wart types HPV27/57, the unusual wart type HPV7, and an excess of Betapapillomavirus types (P = .002), compared with wart specimens from noninfected controls. These findings suggest that HLA testing might assist in stratifying those patients in whom vaccination should be recommended
Lifetime of d-holes at Cu surfaces: Theory and experiment
We have investigated the hole dynamics at copper surfaces by high-resolution
angle-resolved photoemission experiments and many-body quasiparticle GW
calculations. Large deviations from a free-electron-like picture are observed
both in the magnitude and the energy dependence of the lifetimes, with a clear
indication that holes exhibit longer lifetimes than electrons with the same
excitation energy. Our calculations show that the small overlap of d- and
sp-states below the Fermi level is responsible for the observed enhancement.
Although there is qualitative good agreement of our theoretical predictions and
the measured lifetimes, there still exist some discrepancies pointing to the
need of a better description of the actual band structure of the solid.Comment: 15 pages, 7 figures, 1 table, to appear in Phys. Rev.
Surface characterization and surface electronic structure of organic quasi-one-dimensional charge transfer salts
We have thoroughly characterized the surfaces of the organic charge-transfer
salts TTF-TCNQ and (TMTSF)2PF6 which are generally acknowledged as prototypical
examples of one-dimensional conductors. In particular x-ray induced
photoemission spectroscopy turns out to be a valuable non-destructive
diagnostic tool. We show that the observation of generic one-dimensional
signatures in photoemission spectra of the valence band close to the Fermi
level can be strongly affected by surface effects. Especially, great care must
be exercised taking evidence for an unusual one-dimensional many-body state
exclusively from the observation of a pseudogap.Comment: 11 pages, 12 figures, v2: minor changes in text and figure labellin
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