1,173 research outputs found
Superconducting Superstructure for the TESLA Collider
We discuss the new layout of a cavity chain (superstructure) allowing, we
hope, significant cost reduction of the RF system of both linacs of the TESLA
linear collider. The proposed scheme increases the fill factor and thus makes
an effective gradient of an accelerator higher. We present mainly computations
we have performed up to now and which encouraged us to order the copper model
of the scheme, still keeping in mind that experiments with a beam will be
necessary to prove if the proposed solution can be used for the acceleration.Comment: 11 page
Is attending a mental process?
The nature of attention has been the topic of a lively research programme in psychology for over a century. But there is widespread agreement that none of the theories on offer manage to fully capture the nature of attention. Recently, philosophers have become interested in the debate again after a prolonged period of neglect. This paper contributes to the project of explaining the nature of attention. It starts off by critically examining Christopher Mole’s prominent “adverbial” account of attention, which traces the failure of extant psychological theories to their assumption that attending is a kind of process. It then defends an alternative, process-based view of the metaphysics of attention, on which attention is understood as an activity and not, as psychologists seem to implicitly assume, an accomplishment. The entrenched distinction between accomplishments and activities is shown to shed new light on the metaphysics of attention. It also provides a novel diagnosis of the empirical state of play
Using geographic information systems for radon exposure assessment in dwellings in the Oslo region, Norway
Radon exposures were assigned to each residential address in the Oslo region
using a geographic information system (GIS) that included indoor radon
measurements. The results will be used in an epidemiologic study regarding
leukemia and brain cancer. The model is based on 6% of measured
residential buildings. High density of indoor radon measurements allowed us
to develop a buffer model where indoor radon measurements found around each
dwelling were used to assign a radon value for homes lacking radon
measurement.
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Intraclass correlation coefficients (ICCs) were used to study the agreement
between radon values from the buffer method, from indoor
radon values of measured houses, and from a regression model constructed
with radiometric data (<i>e</i><sub>Th</sub>, <i>e</i><sub>U</sub>) and bedrock geology. We obtained good
agreement for both comparisons with ICC values between 0.54 and 0.68.
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GIS offers a useful variety of tools to study the indoor-radon exposure
assessment. By using the buffer method it is more likely that geological
conditions are similar within the buffer and this may take more into account
the variation of radon over short distances. It is also probable that short-distance-scale correlation patterns express similarities in building styles
and living habits. Although the method has certain limitations, we regard it
as acceptable for use in epidemiological studies
Micromegas in a Bulk
In this paper we present a novel way to manufacture the bulk Micromegas
detector. A simple process based on the PCB (Printed Circuit Board) technology
is employed to produce the entire sensitive detector. Such fabrication process
could be extended to very large area detectors made by the industry. The low
cost fabrication together with the robustness of the electrode materials will
make it extremely attractive for several applications ranging from particle
physics and astrophysics to medicineComment: 6 pages, 4 figure
A low background Micromegas detector for the CAST experiment
A low background Micromegas detector has been operating on the CAST
experiment at CERN for the search of solar axions during the first phase of the
experiment (2002-2004). The detector operated efficiently and achieved a very
low level of background rejection ( counts
keVcms) thanks to its good spatial and energy resolution
as well as the low radioactivity materials used in the construction of the
detector. For the second phase of the experiment (2005-2007), the detector will
be upgraded by adding a shielding and including focusing optics. These
improvements should allow for a background rejection better than two orders of
magnitude.Comment: 6 pages, 3 figures To appear on the proceedings of the 9th ICATPP
Conference on AStroparticle, Particle, Space Physics, Detectors and Medical
Physics Application
Association between adiposity after diagnosis of prostate cancer and mortality: systematic review and meta-analysis
OBJECTIVE To explore the associations between adiposity indices, assessed at or after a diagnosis of prostate cancer, and mortality. DESIGN Systematic review and meta-analysis. DATA SOURCES PubMed and Embase, from inception to 16 November 2022. ELIGIBILITY CRITERIA FOR SELECTING STUDIES Cohort studies or randomised controlled trials of men with a diagnosis of prostate cancer that investigated the associations between adiposity (body mass index, waist and hip circumference, waist-to-hip ratio, and subcutaneous and visceral adipose tissue) after diagnosis and mortality outcomes. A modified version of the risk of bias for nutrition observational studies tool was used to assess risk of bias. RESULTS 79 studies were identified that investigated adiposity indices after a diagnosis of prostate cancer in relation to mortality. No randomised controlled trials were found. A non-linear dose-response meta-analysis indicated a J shaped association between body mass index and all-cause mortality (33910 men, 11095 deaths, 17 studies). The highest rate of all-cause mortality was found at the lowest and upper range of the distribution: 11-23% higher rate for a body mass index of 17-21and 4-43% higher rate for a body mass index of 30-40. The association between body mass index and mortality specific to prostate cancer was flat until body mass index reached 26- 27, and then increased linearly by 8-66% for a body mass index of 30-40 (33137 men, 2947 deaths, 13 studies), but the 95% confidence intervals were wide. These associations did not differ in most predefined subgroups by study design, number of deaths, anthropometric assessment, follow-up time, geographical location, prostate cancer risk group, and adjustment variables. No associations were found in meta-analyses between 10cm increases in waist circumference and all-cause mortality or mortality specific to prostate cancer, but only three studies were available. The few studies with data on change in weight, waist-to-hip ratio, and subcutaneous and visceral adipose tissue reported conflicting results. CONCLUSIONS This review suggests that patients with prostate cancer might benefit from maintaining a healthy weight and avoiding obesity. Future studies should investigate adiposity across different stages of cancer survivorship and use various parameters for distribution of adipose tissue
The Micromegas detector of the CAST experiment
A low background Micromegas detector has been operating in the CAST
experiment at CERN for the search of solar axions during the first phase of the
experiment (2002-2004). The detector, made out of low radioactivity materials,
operated efficiently and achieved a very low level of background rejection (5 x
10^-5 counts/keV/cm^2/s) without shielding.Comment: 13 pages, 12 figures and images, submitted to New Journal o
Discovery of Localized Regions of Excess 10-TeV Cosmic Rays
An analysis of 7 years of Milagro data performed on a 10-degree angular scale
has found two localized regions of excess of unknown origin with greater than
12 sigma significance. Both regions are inconsistent with gamma-ray emission
with high confidence. One of the regions has a different energy spectrum than
the isotropic cosmic-ray flux at a level of 4.6 sigma, and it is consistent
with hard spectrum protons with an exponential cutoff, with the most
significant excess at ~10 TeV. Potential causes of these excesses are explored,
but no compelling explanations are found.Comment: Submitted to PhysRevLet
Lichens facilitate seedling recruitment in alpine heath
Abstract Questions How do mat thickness, physical structure and allelopathic properties of terricolous mat-forming lichens affect recruitment of vascular plants in dwarf-shrub and lichen heath vegetation?. Location The mountains of Dovrefjell, central Norway. Methods In autumn, seeds of ten vascular plant species were collected and sown in a common garden experiment with mats of six lichen species and bare-soil controls as experimental treatments. We recorded growing season soil temperature and moisture, and seedling recruitment and growth after one year. The effect of lichen secondary compounds on germination was tested in a growth chamber experiment and compared to the lichen-plant interactions detected under field conditions. Results The lichen mats buffered extreme soil temperatures and soil drying in dry weather, with soils below the thickest mats (Cladonia stellaris and C. rangiferina) experiencing the lowest temperature fluctuations. Seedling recruitment and seedling growth in the field and seed germination in the lab were species-specific. Seedling recruitment rates were overall higher within lichen mats than on bare soil, but the c. 6.5 cm thick mats of C. stellaris reduced recruitment of many species. The lab experiment suggested no overall strong effect of lichen allelopathy on seed germination, and effects on seed germination were only moderately correlated with the lichen-plant interactions observed for seedling recruitment in the field. Conclusions In harsh environments like alpine dwarf-shrub and lichen heaths, the presence of lichens and the resulting amelioration of the microclimate seems more important for vascular plant recruitment than are allelopathic effects often reported in lab experiments. We might therefore expect most terricolous lichens, depending on the plant species in focus, to facilitate rather than hamper the early stages of plant recruitment into lichen-dominated arctic-alpine heath vegetation. This article is protected by copyright. All rights reserved.Peer reviewe
The Study of TeV Variability and Duty Cycle of Mrk 421 from 3 Years of Observations with the Milagro Observatory
TeV flaring activity with time scales as short as tens of minutes and an
orphan TeV flare have been observed from the blazar Markarian 421 (Mrk 421).
The TeV emission from Mrk 421 is believed to be produced by leptonic
synchrotron self-Compton (SSC) emission. In this scenario, correlations between
the X-ray and the TeV fluxes are expected, TeV orphan flares are hardly
explained and the activity (measured as duty cycle) of the source at TeV
energies is expected to be equal or less than that observed in X-rays if only
SSC is considered. To estimate the TeV duty cycle of Mrk 421 and to establish
limits on its variability at different time scales, we continuously observed
Mrk 421 with the Milagro observatory. Mrk 421 was detected by Milagro with a
statistical significance of 7.1 standard deviations between 2005 September 21
and 2008 March 15. The observed spectrum is consistent with previous
observations by VERITAS. We estimate the duty cycle of Mrk 421 for energies
above 1 TeV for different hypothesis of the baseline flux and for different
flare selections and we compare our results with the X-ray duty cycle estimated
by Resconi et al. 2009. The robustness of the results is discussed.Comment: 27 pages, 6 figures, ApJ accepte
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