795 research outputs found
Assessing the importance of a self-generated detachment process in river biofilm models
1. Epilithic biofilm biomass was measured for 14 months in two sites, located up- and downstream of the city of Toulouse in the Garonne River (south-west France). Periodical sampling provided a biomass data set to compare with simulations from the model of Uehlinger, Bürher and Reichert (1996: Freshwater Biology, 36, 249–263.), in order to evaluate the impact of hydraulic disturbance.
2. Despite differences in application conditions (e.g. river size, discharge, frequency of disturbance), the base equation satisfactorily predicted biomass between low and high water periods of the year, suggesting that the flood disturbance regime may be considered a universal mechanism controlling periphyton biomass.
3. However modelling gave no agreement with biomass dynamics during the 7-month long low water period that the river experienced. The influence of other biomass-regulating factors (temperature, light and soluble reactive phosphorus) on temporal biomass dynamics was weak.
4. Implementing a supplementary mechanism corresponding to a temperature-dependent self-generated loss because of heterotrophic processes allowed us to accurately reproduce the observed pattern: a succession of two peaks. This case study suggests that during typical summer low water periods (flow stability and favourable temperature) river biofilm modelling requires self-generated detachment to be considered
The effects of acute and elective cardiac surgery on the anxiety traits of patients with Marfan syndrome
BACKGROUND: Marfan syndrome is a genetic disease, presenting with dysfunction of connective tissues leading to lesions in the cardiovascular and skeletal muscle system. Within these symptoms, the most typical is weakness of the connective tissue in the aorta, manifesting as aortic dilatation (aneurysm). This could, in turn, become annuloaortic ectasia, or life-threatening dissection. As a result, life-saving and preventative cardiac surgical interventions are frequent among Marfan syndrome patients. Aortic aneurysm could turn into annuloaortic ectasia or life-threatening dissection, thus life-saving and preventive cardiac surgical interventions are frequent among patients with Marfan syndrome. We hypothesized that patients with Marfan syndrome have different level of anxiety, depression and satisfaction with life compared to that of the non-clinical patient population. METHODS: Patients diagnosed with Marfan syndrome were divided into 3 groups: those scheduled for prophylactic surgery, those needing acute surgery, and those without need for surgery (n = 9, 19, 17, respectively). To examine the psychological features of the patients, Spielberger's anxiety (STAI) test, Beck's Depression questionnaire (BDI), the Berne Questionnaire of Subjective Well-being, and the Satisfaction with Life scale were applied. RESULTS: A significant difference was found in trait anxiety between healthy individuals and patients with Marfan syndrome after acute life-saving surgery (p 0.1). Finally, a significant, medium size effect was found between patient groups on the Joy in Living scale (F (2.39) = 3.51, p = 0.040, eta2 = 0.15). CONCLUSIONS: Involving psychiatric and mental-health care, in addition to existing surgical treatment interventions, is essential for more successful recovery of patients with Marfan syndrome
From binary to singular: the AGN PSO J334.2028+1.4075 under the high-resolution scope
PSO J334.2028+1.4075 (PSO J334) is a luminous quasar located at redshift
z=2.06. The source gained attention when periodic flux density variations were
discovered in its optical light curve. These variations were initially
interpreted as the variability due to the orbital motion of a supermassive
black hole binary (SMBHB) residing in a single circumbinary accretion disk.
However, subsequent multiwavelength observations provided evidence against the
binary hypothesis as no optical periodicity was found on extended time
baselines. On the other hand, detailed radio analysis with the Karl G. Jansky
Very Large Array (VLA) and the Very Long Baseline Array (VLBA) revealed a
lobe-dominated quasar at kpc scales, and possibly a precessing jet, which could
retain PSO J334 as a binary SMBH candidate. We aim to study both the large- and
small-scale radio structures in PSO J334 to provide additional evidence for or
against the binary scenario. We observed the source at 1.7 GHz with the
European Very Long Baseline Interferometry Network (EVN), and at 1.5 and 6.2
GHz with the VLA, at frequencies that complement the previous radio
interferometric study. Our images reveal a single component at parsec scales
slightly resolved in the southeast-northwest direction and a lobe-dominated
quasar at kiloparsec scales with a complex structure. The source morphology and
polarization in our VLA maps suggest that the jet is interacting with dense
clumps of the ambient medium. While we also observe a misalignment between the
inner jet and the outer lobes, we suggest that this is due to the restarted
nature of the radio jet activity and the possible presence of a warped
accretion disk rather than due to the perturbing effects of a companion SMBH.
Our analysis suggests that PSO J334 is most likely a jetted AGN with a single
SMBH, and there is no clear evidence of a binary SMBH system in its central
engine
Risk of non-Hodgkin lymphoma associated with occupational exposure to solvents,metals, organic dusts and PCBs (Australia)
Objective: Several studies have suggested that there is an occupational component to the causation of non-Hodgkin lymphoma (NHL). We aimed to use accurate means to assess occupational exposures to solvents, metals, organic dusts and polychlorinated biphenyls (PCBs) in a case-control study. Methods: Cases were incident NHLs during 2000 and 2001 in two regions of Australia. Controls were randomly selected from the electoral roll and frequency matched to cases by age, sex and region. A detailed occupational history was taken from each subject. For jobs with likely exposure to the chemicals of interest, additional questions were asked by telephone interview using modified job specific modules. An expert allocated exposures using the information in the job histories and the interviews. Odds ratios were calculated for each exposure adjusting for age, sex, region and ethnic origin. Results: 694 cases and 694 controls (70% and 45% respectively of those potentially eligible) participated. The risk of NHL was increased by about 30% for exposure to any solvent with a dose response relationship, subgroup analysis showed the finding was restricted to solvents other than benzene. Exposure to wood dust also increased the risk of NHL slightly. Exposures to other organic dusts, metals, and PCBs were not strongly related to NHL. Conclusions: The risk of NHL appears to be increased by exposure to solvents other than benzene and possibly to wood dust
Calreticulin mutations affect its chaperone function and perturb the glycoproteome
Calreticulin (CALR) is an endoplasmic reticulum (ER)-retained chaperone that assists glycoproteins in obtaining their structure. CALR mutations occur in patients with myeloproliferative neoplasms (MPNs), and the ER retention of CALR mutants (CALR MUT) is reduced due to a lacking KDEL sequence. Here, we investigate the impact of CALR mutations on protein structure and protein levels in MPNs by subjecting primary patient samples and CALR-mutated cell lines to limited proteolysis-coupled mass spectrometry (LiP-MS). Especially glycoproteins are differentially expressed and undergo profound structural alterations in granulocytes and cell lines with homozygous, but not with heterozygous, CALR mutations. Furthermore, homozygous CALR mutations and loss of CALR equally perturb glycoprotein integrity, suggesting that loss-of-function attributes of mutated CALR chaperones (CALR MUT) lead to glycoprotein maturation defects. Finally, by investigating the misfolding of the CALR glycoprotein client myeloperoxidase (MPO), we provide molecular proof of protein misfolding in the presence of homozygous CALR mutations.
Keywords: CP: Cancer; CP: Molecular biology; calreticulin; chaperone; glycoprotein; limited proteolysis-coupled mass spectrometry; myeloperoxidase; myeloproliferative neoplasm; protein folding; proteome
TANAMI: Tracking Active Galactic Nuclei with Austral Milliarcsecond Interferometry. III. First-epoch S band images
With the emergence of very high energy astronomy (VHE; E>100 GeV), new open
questions were presented to astronomers studying the multi-wavelength emission
from blazars. Answers to these open questions, such as the Doppler crisis, and
finding the location of the high-energy activity have eluded us thus far.
Recently, quasi-simultaneous multi-wavelength monitoring programs have shown
considerable success in investigating blazar activity. After the launch of the
Fermi Gamma-ray Space Telescope in 2008, such quasi-simultaneous observations
across the electromagnetic spectrum became possible. In addition, with very
long baseline interferometry (VLBI) observations we can resolve the central
parsec region of active galactic nuclei (AGN) and compare morphological changes
to the gamma-ray activity to study high-energy emitting blazars. To achieve our
goals, we need sensitive, long-term VLBI monitoring of a complete sample of VHE
detected AGN. We performed VLBI observations of TeV-detected AGN and high
likelihood neutrino associations as of December of 2021 with the Long Baseline
Array (LBA) and other southern hemisphere radio telescopes at 2.3 GHz. In this
paper we present first light TANAMI S-band images, focusing on the TeV-detected
sub-sample of the full TANAMI sample. Apart from these very high
energy-detected sources, we also show images of the two flux density
calibrators and two additional sources included in the observations. We study
the redshift, 0.1-100 GeV photon flux and S-band core brightness temperature
distributions of the TeV-detected objects, and find that flat spectrum radio
quasars and low synchrotron peaked sources on average show higher brightness
temperatures than high-synchrotron-peaked BL Lacs. Sources with bright GeV
gamma-ray emission also show higher brightness temperature values than
gamma-low sources
Adamtsl3 mediates DCC signaling to selectively promote GABAergic synapse function
The molecular code that controls synapse formation and maintenance in vivo has remained quite sparse. Here, we identify that the secreted protein Adamtsl3 functions as critical hippocampal synapse organizer acting through the transmembrane receptor DCC (deleted in colorectal cancer). Traditionally, DCC function has been associated with glutamatergic synaptogenesis and plasticity in response to Netrin-1 signaling. We demonstrate that early post-natal deletion of Adamtsl3 in neurons impairs DCC protein expression, causing reduced density of both glutamatergic and GABAergic synapses. Adult deletion of Adamtsl3 in either GABAergic or glutamatergic neurons does not interfere with DCC-Netrin-1 function at glutamatergic synapses but controls DCC signaling at GABAergic synapses. The Adamtsl3-DCC signaling unit is further essential for activity-dependent adaptations at GABAergic synapses, involving DCC phosphorylation and Src kinase activation. These findings might be particularly relevant for schizophrenia because genetic variants in Adamtsl3 and DCC have been independently linked with schizophrenia in patients
Clinical features and disease progression in older individuals with Rett syndrome
Although long-term survival in Rett syndrome (RTT) has been observed, limited information on older people with RTT exists. We hypothesized that increased longevity in RTT would be associated with genetic variants i
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