577 research outputs found
Magnification as a Tool in Weak Lensing
Weak lensing surveys exploit measurements of galaxy ellipticities. These
measurements are subject to errors which degrade the cosmological information
that can be extracted from the surveys. Here we propose a way of using the
galaxy data themselves to calibrate the measurement errors. In particular, the
cosmic shear field, which causes the galaxies to appear elliptical, also
changes their sizes and fluxes. Information about the sizes and fluxes of the
galaxies can be added to the shape information to obtain more robust
information about the cosmic shear field. The net result will be tighter
constraints on cosmological parameters such as those which describe dark
energy.Comment: 4 pages, 2 figure
A Conditional Luminosity Function Model of the Cosmic Far-Infrared Background Anisotropy Power Spectrum
The cosmic far-infrared background (CFIRB) is expected to be generated by
faint, dusty star-forming galaxies during the peak epoch of galaxy formation.
The anisotropy power spectrum of the CFIRB captures the spatial distribution of
these galaxies in dark matter halos and the spatial distribution of dark matter
halos in the large-scale structure. Existing halo models of CFIRB anisotropy
power spectrum are either incomplete or lead to halo model parameters that are
inconsistent with the galaxy distribution selected at other wavelengths. Here
we present a conditional luminosity function approach to describe the far-IR
bright galaxies. We model the 250 um luminosity function and its evolution with
redshift and model-fit the CFIRB power spectrum at 250 um measured by the
Herschel Space Observatory. We introduce a redshift dependent duty-cycle
parameter so that we are able to estimate the typical duration of the dusty
star formation process in the dark matter halos as a function of redshifts. We
find the duty cycle of galaxies contributing to the far-IR background is 0.3 to
0.5 with a dusty star-formation phase lasting for \sim0.3-1.6 Gyrs. This result
confirms the general expectation that the far-IR background is dominated by
star-forming galaxies in an extended phases, not bright starbursts that are
driven by galaxy mergers and last \sim10-100 Myrs. The halo occupation number
for satellite galaxies has a power-law slope that is close to unity over 0<z<4.
We find that the minimum halo mass for dusty, star-forming galaxies with
L_250>10^{10} L_Sun is 2\times10^{11}M_Sun and 3\times 10^{10}M_Sun at z=1 and
2, respectively. Integrating over the galaxy population with L_250>10^{9}
L_Sun, we find that the cosmic density of dust residing in the dusty,
star-forming galaxies responsible for the background anisotropies
\Omega_{dust}\sim3\times10^{-6} to 2\times10^{-5}.Comment: Accepted for publication in ApJ; 10 pages, 8 figures, 2 table
Customer Referral Behavior: Do Switchers and Stayers Differ?
In today’s highly competitive market environment, service providers are beginning to recognize that customer referral plays an important role in enhancing firm value through cost-effective acquisition of new customers. While a significant body of research has focused on exploring customer referral, surprisingly limited research to date has addressed how customer referral may vary for different customer groups, particularly among switchers and stayers. This article examines the moderating effect of switchers and stayers on the relationships between service quality and perceived value on customer referral behavior. Actual referral data were collected from 441 customers of an Internet Service Provider in two waves for this study. The results show that the effects of positive changes in service quality and perceived value on customer referral behavior are stronger for recently acquired customers (switchers) than for long-term customers (stayers). The findings of the study suggest that investment in service quality and value improvements yield significantly higher returns (through greater customer referrals) for switchers than for stayers. Based on the findings, the authors recommend that service managers should identify and target newly acquired customers, who have switched from different service providers, right from the outset of the relationship with service offerings that signify higher quality and value in order to maximize customer referrals
Prolonged hemophagocytic lymphohistiocytosis syndrome as an initial presentation of Hodgkin lymphoma: a case report
<p>Abstract</p> <p>Introduction</p> <p>Hemophagocytic lymphohistiocytosis is an immune-mediated syndrome that typically has a rapidly progressive course that can result in pancytopenia, coagulopathy, multi-system organ failure and death.</p> <p>Case presentation</p> <p>A 57-year-old Caucasian woman was referred in fulminant hemophagocytic lymphohistiocytosis, with fever, pancytopenia, splenomegaly, mental status changes and respiratory failure. She was found to have stage IV classical Hodgkin lymphoma, in addition to Epstein-Barr virus and cytomegalovirus viremia. Her presentation was preceded by a 3-year prodrome consisting of cytopenia and fever that were partially controlled by steroids and azathioprine.</p> <p>Conclusion</p> <p>Fulminant hemophagocytic lymphohistiocytosis may follow a prodromal phase that possesses features suggestive of a chronic form of hemophagocytic lymphohistiocytosis, but which may also resemble immune cytopenias of other causes. A diagnosis of hemophagocytic lymphohistiocytosis should be considered in the setting of chronic pancytopenia.</p
Repeated exposure reduces the response to impulsive noise in European seabass
This is the final version of the article. Available from the publisher via the DOI in this record.Human activities have changed the acoustic environment of many terrestrial and aquatic ecosystems around the globe. Mounting evidence indicates that the resulting anthropogenic noise can impact the behaviour and physiology of at least some species in a range of taxa. However, the majority of experimental studies have considered only immediate responses to single, relatively short-term noise events. Repeated exposure to noise could lead to a heightened or lessened response. Here, we conduct two long-term (12 week), laboratory-based exposure experiments with European seabass (Dicentrarchus labrax) to examine how an initial impact of different sound types potentially changes over time. Naïve fish showed elevated ventilation rates, indicating heightened stress, in response to impulsive additional noise (playbacks of recordings of pile-driving and seismic surveys), but not to a more continuous additional noise source (playbacks of recordings of ship passes). However, fish exposed to playbacks of pile-driving or seismic noise for 12 weeks no longer responded with an elevated ventilation rate to the same noise type. Fish exposed long-term to playback of pile-driving noise also no longer responded to short-term playback of seismic noise. The lessened response after repeated exposure, likely driven by increased tolerance or a change in hearing threshold, helps explain why fish that experienced 12 weeks of impulsive noise showed no differences in stress, growth or mortality compared to those reared with exposure to ambient-noise playback. Considering how responses to anthropogenic noise change with repeated exposure is important both when assessing likely fitness consequences and the need for mitigation measures.Funding was provided by CGG; SDS held a NERC KE Fellowship (NE/J500616/2). The
authors declare no conflict of interest
Morphology of the Faial Island shelf (Azores): the interplay between volcanic, erosional, depositional, tectonic and mass-wasting processes
[1] The extents of volcanic island shelves result from surf erosion, which enlarges them, and volcanic progradation, which reduces them. However, mass‐wasting, tectonics and sediment deposition also contribute to their morphology. In order to assess the relative significance of these various processes, we have mapped in detail Faial Island's shelf in the Azores archipelago based on interpretation of geophysical and geological data. The nearshore substrates of the island, down to 30–50 m depth, are rocky and covered by volcaniclastic boulder deposits formed by surf action on now‐submerged lava flows. Below those depths, sandy and gravel volcaniclastic beds dominate, building clinoforms up to the shelf edge. In some sectors of the coast, prograding lava has narrowed the shelf, but, in contrast to nearby Pico Island, we find fewer submarine‐emplaced lavas on the shelf. In this island, we interpret the distance between the coastline and the shelf edge as almost entirely a result of a straightforward competition between surf erosion and lava progradation, in which erosion dominates. Therefore shelf width can be used as a proxy for coastline age as well as for wave energy exposure. The stratigraphy of shelf deposits in boomer seismic data is examined in detail to assess the roles of different sediment sources, accommodation space and wave exposure in creating these deposits. We also show evidence of mass‐wasting at the shelf edge and discuss the possible origins of slope instability. Finally, we discuss the contributing role of tectonics for the development of the shelf.publishe
Innovative solutions to sticky situations: Antiadhesive strategies for treating bacterial infections
ABSTRACT
Bacterial adherence to host tissue is an essential process in pathogenesis, necessary for invasion and colonization and often required for the efficient delivery of toxins and other bacterial effectors. As existing treatment options for common bacterial infections dwindle, we find ourselves rapidly approaching a tipping point in our confrontation with antibiotic-resistant strains and in desperate need of new treatment options. Bacterial strains defective in adherence are typically avirulent and unable to cause infection in animal models. The importance of this initial binding event in the pathogenic cascade highlights its potential as a novel therapeutic target. This article seeks to highlight a variety of strategies being employed to treat and prevent infection by targeting the mechanisms of bacterial adhesion. Advancements in this area include the development of novel antivirulence therapies using small molecules, vaccines, and peptides to target a variety of bacterial infections. These therapies target bacterial adhesion through a number of mechanisms, including inhibition of pathogen receptor biogenesis, competition-based strategies with receptor and adhesin analogs, and the inhibition of binding through neutralizing antibodies. While this article is not an exhaustive description of every advancement in the field, we hope it will highlight several promising examples of the therapeutic potential of antiadhesive strategies.</jats:p
A positive role for PEA3 in HER2-mediated breast tumour progression
Overexpression of HER2 is associated with an adverse prognosis in breast cancer. Despite this, the mechanism of its transcriptional regulation remains poorly understood. PEA3, a MAP kinase (MAPK)-activated member of the Ets transcription factor family has been implicated in the transcriptional regulation of HER2. The direction of its modulation remains controversial. We assessed relative levels of PEA3 expression and DNA binding in primary breast cultures derived from patient tumours (n=18) in the presence of an activated MAPK pathway using Western blotting and shift analysis. Expression of PEA3 in breast tumours from patients of known HER2 status (n=107) was examined by immunohistochemistry. In primary breast cancer cell cultures, growth factors induced interaction between PEA3 and its DNA response element. Upregulation of PEA3 expression in the presence of growth factors associated with HER2 positivity and axillary lymph node metastasis (P=0.034 and 0.049, respectively). PEA3 expression in breast cancer tissue associated with reduced disease-free survival (P<0.001), Grade III tumours (P<0.0001) and axillary lymph node metastasis (P=0.026). Co-expression of PEA3 and HER2 significantly associated with rate of recurrence compared to patients who expressed HER2 alone (P=0.0039). These data support a positive role for PEA3 in HER2-mediated oncogenesis in breast cancer
Haematological and Biochemical Reference Values for Healthy Adults in the Middle Belt of Ghana
BACKGROUND: Reference values are very important in clinical management of patients, screening participants for enrollment into clinical trials and for monitoring the onset of adverse events during these trials. The aim of this was to establish gender-specific haematological and biochemical reference values for healthy adults in the central part of Ghana. METHODS: A total of 691 adults between 18 and 59 years resident in the Kintampo North Municipality and South District in the central part of Ghana were randomly selected using the Kintampo Health and Demographic Surveillance System and enrolled in this cross-sectional survey. Out of these, 625 adults made up of 316 males and 309 females were assessed by a clinician to be healthy. Median values and nonparametric 95% reference values for 16 haematology and 22 biochemistry parameters were determined for this population based on the Clinical Laboratory and Standards Institute guidelines. Values established in this study were compared with the Caucasian values being used currently by our laboratory as reference values and also with data from other African and western countries. RESULTS: REFERENCE VALUES ESTABLISHED INCLUDE: haemoglobin 113-164 g/L for males and 88-144 g/L for females; total white blood cell count 3.4-9.2 × 10(9)/L; platelet count 88-352 × 10(9)/L for males and 89-403 × 10(9)/L for females; alanine aminotransferase 8-54 U/L for males and 6-51 U/L for females; creatinine 56-119 µmol/L for males and 53-106 µmol/L for females. Using the haematological reference values based on the package inserts would have screened out up to 53% of potential trial participants and up to 25% of the population using the biochemical parameters. CONCLUSION: We have established a panel of locally relevant reference parameters for commonly used haematological and biochemical tests. This is important as it will help in the interpretation of laboratory results both for clinical management of patients and safety monitoring during a trial
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