677 research outputs found
A road map for defining Good Environmental Status in the deep-sea
The development of tools to assess the Good Environmental Status (GES) in the Deep Sea (DS) is one of the aspects that ATLAS WP3 is addressing. GES assessment in the DS is challenging due to 1) the lack of baseline data, 2) the remoteness of the DS ecosystems, and 3) the limitations of the sampling methods currently available. Throughout the duration of the project, ATLAS will develop a suitable approach to address GES in the DS. During the 2nd General Assembly, we will present a draft for a “road map” to address GES in the DS as well some of the aspects discussed during the 2017 ICES WG on Deep Sea Ecosystems. The temporal and spatial scale at which GES should be assessed in the deep-sea is an important aspect to be considered. Due to the data limited situation and challenges posed to monitoring, it may well be the case that GES will have to be assessed at large spatial and temporal scales when comparing the shallower waters of the European Seas. For similar reasons, the type of indicators to be used may have to be simplified and likely be based on high-level analyses related to traits, pressures/risks, and habitat /ecosystem resilience. Ultimately, the results of the combined analyses of GES descriptors might bring to a potential refining or redefinition of the GES concept for the deep-sea
Risk of hepatocellular carcinoma in chronic hepatitis B: Assessment and modification with current antiviral therapy
SummaryIn the treatment of chronic hepatitis B (CHB), the ultimate goal is preventing hepatitis B virus (HBV)-associated liver disease, including hepatocellular carcinoma (HCC). Recently published studies show that in CHB patients treated with the currently recommended first-line nucleos(t)ide analogs (NAs) entecavir or tenofovir, annual HCC incidences range from 0.01% to 1.4% in non-cirrhotic patients, and from 0.9% to 5.4% in those with cirrhosis. In Asian studies including matched untreated controls, current NA therapy consistently resulted in a significantly lower HCC incidence in patients with cirrhosis, amounting to an overall HCC risk reduction of ∼30%; in non-cirrhotic patients, HCC risk reduction was overall ∼80%, but this was only observed in some studies. For patients of Caucasian origin, no appropriate comparative studies are available to date to evaluate the impact of NA treatment on HCC. Achievement of a virologic response under current NA therapy was associated with a lower HCC risk in Asian, but not Caucasian studies. Studies comparing entecavir or tenofovir with older NAs generally found no difference in HCC risk reduction between agents, except for one study which used no rescue therapy in patients developing lamivudine resistance. Overall, these data indicate that with the current, potent NAs, HCC risk can be reduced but not eliminated, probably due to risk factors that are not amenable to change by antiviral therapy, or events that may have taken place before treatment initiation. Validated pre- and on-therapy HCC risk calculators that inform the best practice for HCC surveillance and facilitate patient counseling would be of great practical value
Reheating the Universe After Multi-Field Inflation
We study in detail (p)reheating after multi-field inflation models with a
particular focus on N-flation. We consider a variety of different couplings
between the inflatons and the matter sector, including both quartic and
trilinear interactions with a light scalar field. We show that the presence of
multiple oscillating inflatons makes parametric resonance inefficient in the
case of the quartic interactions. Moreover, perturbative processes do not
permit a complete decay of the inflaton for this coupling. In order to recover
the hot big bang, we must instead consider trilinear couplings. In this case we
show that strong nonperturbative preheating is possible via multi-field
tachyonic resonance. In addition, late-time perturbative effects do permit a
complete decay of the condensate. We also study the production of gauge fields
for several prototype couplings, finding similar results to the trilinear
scalar coupling. During the course of our analysis we develop the mathematical
theory of the quasi-periodic Mathieu equation, the multi-field generalization
of the Floquet theory familiar from preheating after single field inflation. We
also elaborate on the theory of perturbative decays of a classical inflaton
condensate, which is applicable in single-field models also.Comment: 46+1 pages, 19 figure
Mass-luminosity relation for FGK main sequence stars: metallicity and age contributions
The stellar mass-luminosity relation (MLR) is one of the most famous
empirical "laws", discovered in the beginning of the 20th century. MLR is still
used to estimate stellar masses for nearby stars, particularly for those that
are not binary systems, hence the mass cannot be derived directly from the
observations. It's well known that the MLR has a statistical dispersion which
cannot be explained exclusively due to the observational errors in luminosity
(or mass). It is an intrinsic dispersion caused by the differences in age and
chemical composition from star to star. In this work we discuss the impact of
age and metallicity on the MLR. Using the recent data on mass, luminosity,
metallicity, and age for 26 FGK stars (all members of binary systems, with
observational mass-errors <= 3%), including the Sun, we derive the MLR taking
into account, separately, mass-luminosity, mass-luminosity-metallicity, and
mass-luminosity-metallicity-age. Our results show that the inclusion of age and
metallicity in the MLR, for FGK stars, improves the individual mass estimation
by 5% to 15%.Comment: 7 pages, 4 figures, 1 table, accepted in Astrophysics and Space
Scienc
Coral cities of the deep. Species–habitat associations on the Mingulay Reef Complex
Versión del edito
Autism diagnosis in the United Kingdom: Perspectives of autistic adults, parents and professionals
Accessing an autism diagnosis is a key milestone, both for an individual and their family. Using a qualitative methodology, the current study examined the views and experiences of ten autistic adults, ten parents of children on the autism spectrum, and ten professionals involved in autism diagnosis, all based in the United Kingdom (UK). Interviewing these 30 respondents about the diagnostic process and subsequent support options, the goal was to identify aspects of the diagnostic process that are working well, and areas in which improvements are needed. Using thematic analysis, three key themes were identified: the process of understanding and accepting autism; multiple barriers to satisfaction with the diagnostic process; and inadequate post-diagnostic support provisio
Hepatitis B surface antigen quantification: Why and how to use it in 2011 – A core group report
Quantitative HBsAg had been suggested to be helpful in management of HBV, but assays were cumbersome. The recent availability of commercial quantitative assays has restarted the interest in quantitative serum hepatitis B surface antigen (HBsAg) as a biomarker for prognosis and treatment response in chronic hepatitis B. HBsAg level reflects the transcriptional activity of cccDNA rather than the absolute amount of cccDNA copies. Serum HBsAg level tends to be higher in hepatitis B e antigen (HBeAg)-positive than HBeAg-negative patients. Among patients with a low HBV DNA (<2000IU/ml), HBsAg <1000IU/ml in genotype D HBV infection and HBsAg <100IU/ml in genotype B/C HBV infection is associated with inactive carrier state in HBeAg-negative patients. The HBsAg reduction by nucleos(t)ide analogues (NA) is not as pronounced as by interferon treatment. On peginterferon treatment, sustained responders tend to show greater HBsAg decline than the non-responders. The optimal on-treatment HBsAg cutoff to predict response needs further evaluation in HBeAg-positive patients, but an absence of HBsAg decline together with a <2 log reduction in HBV DNA at week 12 can serve as stopping rule in HBeAg-negative patients with genotype D HBV infection. A rapid serum HBsAg decline during NA therapy may identify patients who will clear HBsAg in the long-term. There are early reports among Asian patients that an HBsAg level of <100IU/ml might predict lower risk of relapse after stopping NA treatment. In clinical practice, serum HBsAg level should be used together with, but not as a substitute for, HBV DNA
- …