817 research outputs found
Mind The Gap
We discuss an optimisation criterion for the exact renormalisation group
based on the inverse effective propagator, which displays a gap. We show that a
simple extremisation of the gap stabilises the flow, leading to better
convergence of approximate solutions towards the physical theory. This improves
the reliability of truncations, most relevant for any high precision
computation. These ideas are closely linked to the removal of a spurious scheme
dependence and a minimum sensitivity condition. The issue of predictive power
and a link to the Polchinski RG are discussed as well. We illustrate our
findings by computing critical exponents for the Ising universality class.Comment: 6 pages, Talk presented at 2nd Conference on Exact Renormalization
Group (ERG2000), Rome, Italy, 18-22 Sep 200
Appetite, food intake, and gut hormone responses to glycomacropeptide protein ingestion in older adults: : A feasibility, acceptability, and pilot study
We would like express huge gratitude to our participants for taking part, and for making data collection such an enjoyable experience for the research team. We would like to thank our students Vicky Catterall, Beth Minion, Joe Ashworth, Monty Hardcastle, and Anna Brooks for supporting data collection. We also thank Agropur Ingredients (Eden Prairie, MN, USA) for providing GMP.Peer reviewe
Episomal Viral cDNAs Identify a Reservoir That Fuels Viral Rebound after Treatment Interruption and That Contributes to Treatment Failure
Viral reservoirs that persist in HIV-1 infected individuals on antiretroviral therapy (ART) are the major obstacle to viral eradication. The identification and definition of viral reservoirs in patients on ART is needed in order to understand viral persistence and achieve the goal of viral eradication. We examined whether analysis of episomal HIV-1 genomes provided the means to characterize virus that persists during ART and whether it could reveal the virus that contributes to treatment failure in patients on ART. For six individuals in which virus replication was highly suppressed for at least 20 months, proviral and episomal genomes present just prior to rebound were phylogenetically compared to RNA genomes of rebounding virus after therapy interruption. Episomal envelope sequences, but not proviral envelope sequences, were highly similar to sequences in rebounding virus. Since episomes are products of recent infections, the phylogenetic relationships support the conclusion that viral rebound originated from a cryptic viral reservoir. To evaluate whether the reservoir revealed by episomal sequence analysis was of clinical relevance, we examined whether episomal sequences define a viral population that contributes to virologic failure in individuals receiving the CCR5 antagonist, Vicriviroc. Episomal envelope sequences at or near baseline predicted treatment failure due to the presence of X4 or D/M (dual/mixed) viral variants. In patients that did not harbor X4 or D/M viruses, the basis for Vicriviroc treatment failure was indeterminate. Although these samples were obtained from viremic patients, the assay would be applicable to a large percentage of aviremic patients, based on previous studies. Summarily, the results support the use of episomal HIV-1 as an additional or alternative approach to traditional assays to characterize virus that is maintained during long-term, suppressive ART
Impacts of forestry planting on primary production in upland lakes from north-west Ireland
Planted forests are increasing in many upland regions world-wide, but knowledge about their potential effects on algal communities of catchment lakes is relatively unknown. Here the effects of afforestation were investigated using palaeolimnology at six upland lake sites in the north-west of Ireland subject to different extents of forest plantation cover (4-64% of catchment area). 210Pb dated sediment cores were analysed for carotenoid pigments from algae, stable isotopes of bulk carbon (δ13C) and nitrogen (δ15N), and C/N ratios. In lakes with >50% of their catchment area covered by plantations, there were two- to six-fold increases in pigments from cryptophytes (alloxanthin) and significant but lower increases (39-116%) in those from colonial cyanobacteria (canthaxanthin), but no response from biomarkers of total algal abundance (β-carotene). In contrast, lakes in catchments with <20% afforestation exhibited no consistent response to forestry practices, although all lakes exhibited fluctuations in pigments and geochemical variables due to peat cutting and upland grazing prior to forest plantation. Taken together, patterns suggest that increases in cyanobacteria and cryptophyte abundance reflect a combination of mineral and nutrient enrichment associated with forest fertilisation and organic matter influx which may have facilitated growth of mixotrophic taxa. This study demonstrates that planted forests can alter the abundance and community structure of algae in upland humic lakes of Ireland and Northern Ireland, despite long histories of prior catchment disturbance
Episomal Viral cDNAs Identify a Reservoir That Fuels Viral Rebound after Treatment Interruption and That Contributes to Treatment Failure
Viral reservoirs that persist in HIV-1 infected individuals on antiretroviral therapy (ART) are the major obstacle to viral eradication. The identification and definition of viral reservoirs in patients on ART is needed in order to understand viral persistence and achieve the goal of viral eradication. We examined whether analysis of episomal HIV-1 genomes provided the means to characterize virus that persists during ART and whether it could reveal the virus that contributes to treatment failure in patients on ART. For six individuals in which virus replication was highly suppressed for at least 20 months, proviral and episomal genomes present just prior to rebound were phylogenetically compared to RNA genomes of rebounding virus after therapy interruption. Episomal envelope sequences, but not proviral envelope sequences, were highly similar to sequences in rebounding virus. Since episomes are products of recent infections, the phylogenetic relationships support the conclusion that viral rebound originated from a cryptic viral reservoir. To evaluate whether the reservoir revealed by episomal sequence analysis was of clinical relevance, we examined whether episomal sequences define a viral population that contributes to virologic failure in individuals receiving the CCR5 antagonist, Vicriviroc. Episomal envelope sequences at or near baseline predicted treatment failure due to the presence of X4 or D/M (dual/mixed) viral variants. In patients that did not harbor X4 or D/M viruses, the basis for Vicriviroc treatment failure was indeterminate. Although these samples were obtained from viremic patients, the assay would be applicable to a large percentage of aviremic patients, based on previous studies. Summarily, the results support the use of episomal HIV-1 as an additional or alternative approach to traditional assays to characterize virus that is maintained during long-term, suppressive ART
Impacts of forestry planting on primary production in upland lakes from north-west Ireland
Planted forests are increasing in many upland regions worldwide, but knowledge about their potential effects on algal communities of catchment lakes is relatively unknown. Here, the effects of afforestation were investigated using palaeolimnology at six upland lake sites in the north-west of Ireland subject to different extents of forest plantation cover (4–64% of catchment area). 210Pb-dated sediment cores were analysed for carotenoid pigments from algae, stable isotopes of bulk carbon (δ13C) and nitrogen (δ15N), and C/N ratios. In lakes with >50% of their catchment area covered by plantations, there were two- to sixfold increases in pigments from cryptophytes (alloxanthin) and significant but lower increases (39–116%) in those from colonial cyanobacteria (canthaxanthin), but no response from biomarkers of total algal abundance (β-carotene). In contrast, lakes in catchments with <20% afforestation exhibited no consistent response to forestry practices, although all lakes exhibited fluctuations in pigments and geochemical variables due to peat cutting and upland grazing prior to forest plantation. Taken together, patterns suggest that increases in cyanobacteria and cryptophyte abundance reflect a combination of mineral and nutrient enrichment associated with forest fertilization and organic matter influx which may have facilitated growth of mixotrophic taxa. This study demonstrates that planted forests can alter the abundance and community structure of algae in upland humic lakes of Ireland and Northern Ireland, despite long histories of prior catchment disturbance
Experimental demonstration of a squeezing enhanced power recycled Michelson interferometer for gravitational wave detection
Interferometric gravitational wave detectors are expected to be limited by
shot noise at some frequencies. We experimentally demonstrate that a power
recycled Michelson with squeezed light injected into the dark port can overcome
this limit. An improvement in the signal-to-noise ratio of 2.3dB is measured
and locked stably for long periods of time. The configuration, control and
signal readout of our experiment are compatible with current gravitational wave
detector designs. We consider the application of our system to long baseline
interferometer designs such as LIGO.Comment: 4 pages 4 figure
Exoplanet Biosignatures: Observational Prospects
Exoplanet hunting efforts have revealed the prevalence of exotic worlds with
diverse properties, including Earth-sized bodies, which has fueled our endeavor
to search for life beyond the Solar System. Accumulating experiences in
astrophysical, chemical, and climatological characterization of uninhabitable
planets are paving the way to characterization of potentially habitable
planets. In this paper, we review our possibilities and limitations in
characterizing temperate terrestrial planets with future observational
capabilities through 2030s and beyond, as a basis of a broad range of
discussions on how to advance "astrobiology" with exoplanets. We discuss the
observability of not only the proposed biosignature candidates themselves, but
also of more general planetary properties that provide circumstantial evidence,
since the evaluation of any biosignature candidate relies on their context.
Characterization of temperate Earth-size planets in the coming years will focus
on those around nearby late-type stars. JWST and later 30 meter-class
ground-based telescopes will empower their chemical investigations.
Spectroscopic studies of potentially habitable planets around solar-type stars
will likely require a designated spacecraft mission for direct imaging,
leveraging technologies that are already being developed and tested as part of
the WFIRST mission. Successful initial characterization of a few nearby targets
will be an important touchstone toward a more detailed scrutiny and a larger
survey that are envisioned beyond 2030. The broad outlook this paper presents
may help develop new observational techniques to detect relevant features as
well as frameworks to diagnose planets based on the observables.Comment: part of a series of 5 review manuscripts of the NExSS Exoplanet
Biosgnatures Worksho
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