210 research outputs found
A novel determination of the local dark matter density
We present a novel study on the problem of constructing mass models for the
Milky Way, concentrating on features regarding the dark matter halo component.
We have considered a variegated sample of dynamical observables for the Galaxy,
including several results which have appeared recently, and studied a 7- or
8-dimensional parameter space - defining the Galaxy model - by implementing a
Bayesian approach to the parameter estimation based on a Markov Chain Monte
Carlo method. The main result of this analysis is a novel determination of the
local dark matter halo density which, assuming spherical symmetry and either an
Einasto or an NFW density profile is found to be around 0.39 GeV cm with
a 1- error bar of about 7%; more precisely we find a for the Einasto profile and for the NFW. This is in contrast to the
standard assumption that is about 0.3 GeV cm with an
uncertainty of a factor of 2 to 3. A very precise determination of the local
halo density is very important for interpreting direct dark matter detection
experiments. Indeed the results we produced, together with the recent accurate
determination of the local circular velocity, should be very useful to
considerably narrow astrophysical uncertainties on direct dark matter
detection.Comment: 31 pages,11 figures; minor changes in the text; two figures adde
Description of the inelastic collision of two solitary waves for the BBM equation
We prove that the collision of two solitary waves of the BBM equation is
inelastic but almost elastic in the case where one solitary wave is small in
the energy space. We show precise estimates of the nonzero residue due to the
collision. Moreover, we give a precise description of the collision phenomenon
(change of size of the solitary waves).Comment: submitted for publication. Corrected typo in Theorem 1.
Model Analysis of Time Reversal Symmetry Test in the Caltech Fe-57 Gamma-Transition Experiment
The CALTECH gamma-transition experiment testing time reversal symmetry via
the E2/M1 mulipole mixing ratio of the 122 keV gamma-line in Fe-57 has already
been performed in 1977. Extending an earlier analysis in terms of an effective
one-body potential, this experiment is now analyzed in terms of effective one
boson exchange T-odd P-even nucleon nucleon potentials. Within the model space
considered for the Fe-57 nucleus no contribution from isovector rho-type
exchange is possible. The bound on the coupling strength phi_A from effective
short range axial-vector type exchange induced by the experimental bound on
sin(eta) leads to phi_A < 10^{-2}.Comment: 5 pages, RevTex 3.
Reconceptualising adaptation to climate change as part of pathways of change and response
The need to adapt to climate change is now widely recognised as evidence of its impacts on social and natural systems grows and greenhouse gas emissions continue unabated. Yet efforts to adapt to climate change, as reported in the literature over the last decade and in selected case studies, have not led to substantial rates of implementation of adaptation actions despite substantial investments in adaptation science. Moreover, implemented actions have been mostly incremental and focused on proximate causes; there are far fewer reports of more systemic or transformative actions. We found that the nature and effectiveness of responses was strongly influenced by framing. Recent decision-oriented approaches that aim to overcome this situation are framed within a "pathways" metaphor to emphasise the need for robust decision making within adaptive processes in the face of uncertainty and inter-temporal complexity. However, to date, such "adaptation pathways" approaches have mostly focused on contexts with clearly identified decision-makers and unambiguous goals; as a result, they generally assume prevailing governance regimes are conducive for adaptation and hence constrain responses to proximate causes of vulnerability. In this paper, we explore a broader conceptualisation of "adaptation pathways" that draws on 'pathways thinking' in the sustainable development domain to consider the implications of path dependency, interactions between adaptation plans, vested interests and global change, and situations where values, interests, or institutions constrain societal responses to change. This re-conceptualisation of adaptation pathways aims to inform decision makers about integrating incremental actions on proximate causes with the transformative aspects of societal change. Case studies illustrate what this might entail. The paper ends with a call for further exploration of theory, methods and procedures to operationalise this broader conceptualisation of adaptation
A phase 2, randomized, double-blind, placebo- controlled study of chemo-immunotherapy combination using motolimod with pegylated liposomal doxorubicin in recurrent or persistent ovarian cancer: a Gynecologic Oncology Group partners study.
A phase 2, randomized, placebo-controlled trial was conducted in women with recurrent epithelial ovarian carcinoma to evaluate the efficacy and safety of motolimod-a Toll-like receptor 8 (TLR8) agonist that stimulates robust innate immune responses-combined with pegylated liposomal doxorubicin (PLD), a chemotherapeutic that induces immunogenic cell death.
Women with ovarian, fallopian tube, or primary peritoneal carcinoma were randomized 1 : 1 to receive PLD in combination with blinded motolimod or placebo. Randomization was stratified by platinum-free interval (≤6 versus >6-12 months) and Gynecologic Oncology Group (GOG) performance status (0 versus 1). Treatment cycles were repeated every 28 days until disease progression.
The addition of motolimod to PLD did not significantly improve overall survival (OS; log rank one-sided P = 0.923, HR = 1.22) or progression-free survival (PFS; log rank one-sided P = 0.943, HR = 1.21). The combination was well tolerated, with no synergistic or unexpected serious toxicity. Most patients experienced adverse events of fatigue, anemia, nausea, decreased white blood cells, and constipation. In pre-specified subgroup analyses, motolimod-treated patients who experienced injection site reactions (ISR) had a lower risk of death compared with those who did not experience ISR. Additionally, pre-treatment in vitro responses of immune biomarkers to TLR8 stimulation predicted OS outcomes in patients receiving motolimod on study. Immune score (tumor infiltrating lymphocytes; TIL), TLR8 single-nucleotide polymorphisms, mutational status in BRCA and other DNA repair genes, and autoantibody biomarkers did not correlate with OS or PFS.
The addition of motolimod to PLD did not improve clinical outcomes compared with placebo. However, subset analyses identified statistically significant differences in the OS of motolimod-treated patients on the basis of ISR and in vitro immune responses. Collectively, these data may provide important clues for identifying patients for treatment with immunomodulatory agents in novel combinations and/or delivery approaches.
Clinicaltrials.gov, NCT 01666444
Observing the First Stars and Black Holes
The high sensitivity of JWST will open a new window on the end of the
cosmological dark ages. Small stellar clusters, with a stellar mass of several
10^6 M_sun, and low-mass black holes (BHs), with a mass of several 10^5 M_sun
should be directly detectable out to redshift z=10, and individual supernovae
(SNe) and gamma ray burst (GRB) afterglows are bright enough to be visible
beyond this redshift. Dense primordial gas, in the process of collapsing from
large scales to form protogalaxies, may also be possible to image through
diffuse recombination line emission, possibly even before stars or BHs are
formed. In this article, I discuss the key physical processes that are expected
to have determined the sizes of the first star-clusters and black holes, and
the prospect of studying these objects by direct detections with JWST and with
other instruments. The direct light emitted by the very first stellar clusters
and intermediate-mass black holes at z>10 will likely fall below JWST's
detection threshold. However, JWST could reveal a decline at the faint-end of
the high-redshift luminosity function, and thereby shed light on radiative and
other feedback effects that operate at these early epochs. JWST will also have
the sensitivity to detect individual SNe from beyond z=10. In a dedicated
survey lasting for several weeks, thousands of SNe could be detected at z>6,
with a redshift distribution extending to the formation of the very first stars
at z>15. Using these SNe as tracers may be the only method to map out the
earliest stages of the cosmic star-formation history. Finally, we point out
that studying the earliest objects at high redshift will also offer a new
window on the primordial power spectrum, on 100 times smaller scales than
probed by current large-scale structure data.Comment: Invited contribution to "Astrophysics in the Next Decade: JWST and
Concurrent Facilities", Astrophysics & Space Science Library, Eds. H.
Thronson, A. Tielens, M. Stiavelli, Springer: Dordrecht (2008
Effort-reward imbalance at work and risk of type 2 diabetes in a national sample of 50,552 workers in Denmark: A prospective study linking survey and register data
Objective: To examine the prospective relation between effort-reward imbalance at work and risk of type 2 diabetes.Methods: We included 50,552 individuals from a national survey of the working population in Denmark, aged 30-64 years and diabetes-free at baseline. Effort-reward imbalance was defined, in accordance with the literature, as a mismatch between high efforts at work (e.g. high work pace, time pressure), and low rewards received in return (e.g. low recognition, job insecurity) and assessed as a continuous and a categorical variable. Incident type 2 diabetes was identified in national health registers. Using Cox regression we calculated hazard ratios (HR) and 95% confidence intervals (95% CI) for estimating the association between effort-reward imbalance at baseline and risk of onset of type 2 diabetes during follow-up, adjusted for sex, age, socioeconomic status, cohabitation, children at home, migration background, survey year and sample method.Results: During 136,239 person-years of follow-up (mean = 2.7 years) we identified 347 type 2 diabetes cases (25.5 cases per 10,000 person-years). For each one standard deviation increase of the effort-reward imbalance score at baseline, the fully adjusted risk of type 2 diabetes during follow-up increased by 9% (HR: 1.09, 95% CI: 0.98-1.21). When we used effort-reward imbalance as a dichotomous variable, exposure to effort-reward imbalance was associated with an increased risk of type 2 diabetes with a HR of 1.27 (95% CI: 1.02-1.58).Conclusion The results of this nationwide study of the Danish workforce suggest that effort-reward imbalance at work may be a risk factor for type 2 diabetes
Sediment routing and basin evolution in Proterozoic to Mesozoic east Gondwana: A case study from southern Australia
Sedimentary rocks along the southern margin of Australia host an important record of the break-up history of east Gondwana, as well as fragments of a deeper geological history, which collectively help inform the geological evolution of a vast and largely underexplored region. New drilling through Cenozoic cover has allowed examination of the Cretaceous rift-related Madura Shelf sequence (Bight Basin), and identification of two new stratigraphic units beneath the shelf; the possibly Proterozoic Shanes Dam Conglomerate and the interpreted Palaeozoic southern Officer Basin unit, the Decoration Sandstone. Recognition of these new units indicates an earlier basinal history than previously known. Lithostratigraphy of the new drillcore has been integrated with that published from onshore and offshore cores to present isopach maps of sedimentary cover on the Madura Shelf. New palynological data demonstrate progression from more localised freshwater-brackish fluvio-lacustrine clastics in the early Cretaceous (Foraminisporis wonthaggiensis – Valanginian to Barremian) to widespread topography-blanketing, fully marine, glauconitic mudrocks in the mid Cretaceous (Endoceratium ludbrookiae – Albian). Geochronology and Hf-isotope geochemistry show detrital zircon populations from the Madura Shelf are comparable to those from the southern Officer Basin, as well as Cenozoic shoreline and palaeovalley sediments in the region. The detrital zircon population from the Shanes Dam Conglomerate is defined by a unimodal ~1400 Ma peak, which correlates with directly underlying crystalline basement of the Madura Province. Peak ages of ~1150 Ma and ~1650 Ma dominate the age spectra of all other samples, indicating a stable sediment reservoir through much of the Phanerozoic, with sediments largely sourced from the Albany-Fraser Orogen and Musgrave Province (directly and via multiple recycling events). The Madura Shelf detrital zircon population differs from published data for the Upper CretaceousCeduna Delta to the east, indicating significant differences in sediment provenance and routing between the Ceduna Sub-basin and central Bight Basin
Clustering Algorithms: Their Application to Gene Expression Data
Gene expression data hide vital information required to understand the biological process that takes place in a particular organism in relation to its environment. Deciphering the hidden patterns in gene expression data proffers a prodigious preference to strengthen the understanding of functional genomics. The complexity of biological networks and the volume of genes present increase the challenges of comprehending and interpretation of the resulting mass of data, which consists of millions of measurements; these data also inhibit vagueness, imprecision, and noise. Therefore, the use of clustering techniques is a first step toward addressing these challenges, which is essential in the data mining process to reveal natural structures and iden-tify interesting patterns in the underlying data. The clustering of gene expression data has been proven to be useful in making known the natural structure inherent in gene expression data, understanding gene functions, cellular processes, and subtypes of cells, mining useful information from noisy data, and understanding gene regulation. The other benefit of clustering gene expression data is the identification of homology, which is very important in vaccine design. This review examines the various clustering algorithms applicable to the gene expression data in order to discover and provide useful knowledge of the appropriate clustering technique that will guarantee stability and high degree of accuracy in its analysis procedure
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