Upper Limits on the Extragalactic Background Light from the Gamma-Ray Spectra of Blazars

The direct measurement of the extragalactic background light (EBL) is difficult at optical to infrared wavelengths because of the strong foreground radiation originating in the Solar System. Very high energy (VHE, E$>$100 GeV) gamma rays interact with EBL photons of these wavelengths through pair production. In this work, the available VHE spectra from six blazars are used to place upper limits on the EBL. These blazars have been detected over a range of redshifts and a steepening of the spectral index is observed with increasing source distance. This can be interpreted as absorption by the EBL. In general, knowledge of the intrinsic source spectrum is necessary to determine the density of the intervening EBL. Motivated by the observed spectral steepening with redshift, upper limits on the EBL are derived by assuming that the intrinsic spectra of the six blazars are $\propto E^{-1.8}$. Upper limits are then placed on the EBL flux at discrete energies without assuming a specific spectral shape for the EBL. This is an advantage over other methods since the EBL spectrum is uncertain.Comment: 33 pages, 14 figures, accepted by Ap

Shortened Lung Clearance Index is a repeatable and sensitive test in children and adults with cystic fibrosis

BACKGROUND: Lung clearance index (LCI) derived from sulfur hexafluoride (SF6) multiple breath washout (MBW) is a sensitive measure of lung disease in people with cystic fibrosis (CF). However, it can be time-consuming, limiting its use clinically. AIM: To compare the repeatability, sensitivity and test duration of LCI derived from washout to 1/30th (LCI1/30), 1/20th (LCI1/20) and 1/10th (LCI1/10) to 'standard' LCI derived from washout to 1/40th initial concentration (LCI1/40). METHODS: Triplicate MBW test results from 30 clinically stable people with CF and 30 healthy controls were analysed retrospectively. MBW tests were performed using 0.2% SF6 and a modified Innocor device. All LCI end points were calculated using SimpleWashout software. Repeatability was assessed using coefficient of variation (CV%). The proportion of people with CF with and without abnormal LCI and forced expiratory volume in 1 s (FEV1) % predicted was compared. Receiver operating characteristic (ROC) curve statistics were calculated. Test duration of all LCI end points was compared using paired t tests. RESULTS: In people with CF, LCI1/40 CV% (p=0.16), LCI1/30 CV%, (p=0.53), LCI1/20 CV% (p=0.14) and LCI1/10 CV% (p=0.25) was not significantly different to controls. The sensitivity of LCI1/40, LCI1/30 and LCI1/20 to the presence of CF was equal (67%). The sensitivity of LCI1/10 and FEV1% predicted was lower (53% and 47% respectively). Area under the ROC curve (95% CI) for LCI1/40, LCI1/30, LCI1/20, LCI1/10 and FEV1% predicted was 0.89 (0.80 to 0.97), 0.87 (0.77 to 0.96), 0.87 (0.78 to 0.96), 0.83 (0.72 to 0.94) and 0.73 (0.60 to 0.86), respectively. Test duration of LCI1/30, LCI1/20 and LCI1/10 was significantly shorter compared with the test duration of LCI1/40 in people with CF (p<0.0001) equating to a 5%, 9% and 15% time saving, respectively. CONCLUSIONS: In this study, LCI1/20 was a repeatable and sensitive measure with equal diagnostic performance to LCI1/40. LCI1/20 was shorter, potentially offering a more feasible research and clinical measure

Draft Genome Sequences of 15 Isolates of Listeria monocytogenes Serotype 1/2a, Subgroup ST204

Listeria monocytogenes sequence type 204 (ST204) strains have been isolated from a range of food, environmental, and clinical sources in Australia. This study describes the draft genome sequences of 15 isolates collected from meat and dairy associated sources

Histone-DNA contacts in structure/function relationships of nucleosomes as revealed by crosslinking

The magnitude of the problem of understanding the structure/function relationships of eukaryotic chromosomes can be appreciated from the fact that the human diploid genome contains more than 2 meters of DNA packaged into 46 chromosomes, each at metaphase being several microns in length. Each chromatid of a chromosome contains a single DNA molecule several centimeters in length. In addition to the DNA, chromosomes contain an equal weight of histones and an equal weight of non-histone chromosomal proteins. These histones are the major chromosomal structural proteins. The non-histone chromosomal proteins are involved in the DNA processes of transcription and replication, in chromosome organization and in nuclear architecture. Polytene chromosomes with their bands and interbands and puffs of active genetic loci provide visual evidence for long range order as do the bands and interbands of mammalian metaphase chromosomes. The gentle removal of histones and all but the most tightly bound 2--3% of non-histone proteins from metaphase chromosomes revealed by electron microscopy a residual protein scaffold constraining a halo of DNA loops extending out from the scaffold

Bypass or Angioplasty for Severe Limb Ischaemia? A Delphi Consensus Study

AbstractObjectives: to examine the level of agreement among vascular surgeons and interventional radiologists regarding their preference for the surgical or endovascular management of severe limb ischaemia.Design: Delphi consensus study using 596 different hypothetical patient scenarios.Participants: Delphi consensus group for the Bypass versus Angioplasty in Severe Ischaemia of the Leg (BASIL) trial.Methods: twenty consultant vascular surgeons and 17 interventional radiologists completed both rounds of the study. The scenarios detailed the anatomical extent of disease, whether the patients had rest pain only or had tissue loss, and whether or not a suitable vein for bypass was available. Panellists were asked to score their treatment preference for either surgery or angioplasty on an eight-point scale. Outliers (top 10% and bottom 10% responses) were removed. If the remaining 80% of responses fell within a 3-point range, this was defined as “agreement”. If they did not, this was considered “disagreement”.Results: there was substantial disagreement in 484 (81%) of scenarios in round 1 and 401 (67%) in round 2. This disagreement was greater among surgeon than radiologists in both round 1 (83 vs 65%) and round 2 (69 vs 42%). Surgeons also demonstrated less convergence between rounds.Conclusions: there is substantial disagreement between and among surgeons and radiologists with regard to the appropriateness of surgery or angioplasty for severe limb ischaemia. This lack of consensus stems from the absence of an evidence base and means that the same patient may receive entirely different treatment depending on which hospital and consultant they attend. Not only may this unexplained variation be clinically unsatisfactory, it has major implications for the planning and use of health service resources