735 research outputs found
The mass ratio and the orbital parameters of the sdOB binary AA Doradus
The time sequence of 105 spectra covering one full orbital period of AA Dor
has been analyzed. Direct determination of Vsini for the sdOB component from 97
spectra outside of the eclipse for the lines MgII 4481 A and SiIV 4089 A
clearly indicated a substantially smaller value than estimated before. Detailed
modelling of line profile variations for 8 spectra during the eclipse for the
MgII 4481 A line, combined with the out-of-eclipse fits, gave Vsini =
31.8+/-1.8 km/s. The previous determinations of Vsini, based on the HeII 4686 A
line, appear to be invalid because of the large natural broadening of the line.
With the assumption of the solid-body, synchronous rotation of the sdOB
primary, the measured values of the semi-amplitude K1 and Vsini lead to the
mass ratio q = 0.213+/-0.013 which in turn gives K2 and thus the masses and
radii of both components. The sdOB component appears to be less massive than
assumed before, M1 = 0.25+/-0.05 Msol, but the secondary has its mass-radius
parameters close to theoretically predicted for a brown dwarf, M2 =
0.054+/-0.010 Msol and R2 = 0.089+/-0.005 Rsol. Our results do not agree with
the recent determination of Vuckovic et al. 2008 based on a K2 estimate from
line-profile asymmetries.Comment: Accepted by MNRA
Nimbus 7 Solar Backscatter Ultraviolet (SBUV) spectral scan solar irradiance and Earth radiance product user's guide
The archived tape products from the spectral scan mode measurements of solar irradiance (SUNC tapes) and Earth radiance (EARTH tapes) by the Solar Backscatter UV (SBUV) instrument aboard Nimbus 7 are described. Incoming radiation from 160 to 400 nm is measured at intervals of 0.2 nm. The scan-to-scan repeatability of the solar irradiance measurements ranges from approximately 0.5 to 1 percent longward of 280 nm, to 2 percent around 210 nm and 4 percent near 175 nm. The repeatability of the Earth radiance values ranges from 2 to 3 percent at longer wavelengths and low zenith angles to 10 percent at shorter wavelengths and high zenith angles. The tape formats are described in detail, including file structure and contents of each type of record. Catalogs of the tapes and the time period covered are provided, along with lists of the days lacking solar irradiance measurements and the days dedicated to Earth radiance measurements. The method for production of the tapes is outlined and quality control measures are described. How radiances and irradiances are derived from the raw counts, the corrections for changes in instrument sensitivity, and related uncertainties are discussed
Emergence of behavior in a self-organized living matter network
What is the origin of behavior? Although typically associated with a nervous system, simple life forms also show complex behavior – thus serving as a model to study how behaviors emerge. Among them, the slime mold Physarum polycephalum, growing as a single giant cell, is renowned for its sophisticated behavior. Here, we show how locomotion and morphological adaptation behavior emerge from self-organized patterns of rhythmic contractions of the actomyosin lining of the tubes making up the network-shaped organism. We quantify the spatio-temporal contraction dynamics by decomposing experimentally recorded contraction patterns into spatial contraction modes. Surprisingly, we find a continuous spectrum of modes, as opposed to few dominant modes. Over time, activation of modes along this continuous spectrum is highly dynamic, resulting in contraction patterns of varying regularity. We show that regular patterns are associated with stereotyped behavior by triggering a behavioral response with a food stimulus. Furthermore, we demonstrate that the continuous spectrum of modes and the existence of irregular contraction patterns persist in specimens with a morphology as simple as a single tube. Our data suggests that the continuous spectrum of modes allows for dynamic transitions between a plethora of specific behaviors with transitions marked by highly irregular contraction states. By mapping specific behaviors to states of active contractions, we provide the basis to understand behavior’s complexity as a function of biomechanical dynamics. This perspective will likely stimulate bio-inspired design of soft robots with a similarly rich behavioral repertoire as P. polycephalum
The PPIP5K Family Member Asp1 Controls Inorganic Polyphosphate Metabolism in S. pombe
Inorganic polyphosphate (polyP) which is ubiquitously present in both prokaryotic and eukaryotic cells, consists of up to hundreds of orthophosphate residues linked by phosphoanhydride bonds. The biological role of this polymer is manifold and diverse and in fungi ranges from cell cycle control, phosphate homeostasis and virulence to post-translational protein modification. Control of polyP metabolism has been studied extensively in the budding yeast Saccharomyces cerevisiae. In this yeast, a specific class of inositol pyrophosphates (IPPs), named IP7, made by the IP6K family member Kcs1 regulate polyP synthesis by associating with the SPX domains of the vacuolar transporter chaperone (VTC) complex. To assess if this type of regulation was evolutionarily conserved, we determined the elements regulating polyP generation in the distantly related fission yeast Schizosaccharomyces pombe. Here, the VTC machinery is also essential for polyP generation. However, and in contrast to S. cerevisiae, a different IPP class generated by the bifunctional PPIP5K family member Asp1 control polyP metabolism. The analysis of Asp1 variant S. pombe strains revealed that cellular polyP levels directly correlate with Asp1-made IP8 levels, demonstrating a dose-dependent regulation. Thus, while the mechanism of polyP synthesis in yeasts is conserved, the IPP player regulating polyP metabolism is diverse
Vitality of lichens under different light climates in an Araucaria forest (PrĂł-Mata RS, South Brazil) as determined by chlorophyll fluorescence
“everything in one place”
Purpose: To describe older adults’ perspectives on a new patient education
manual for the recovery process after hip fracture. Materials and methods: The
Fracture Recovery for Seniors at Home (FReSH) Start manual is an evidence-
based manual for older adults with fall-related hip fracture. The manual aims
to support the transition from hospital to home by facilitating self-
management of the recovery process. We enrolled 31 community-dwelling older
adults with previous fall-related hip fracture and one family member. We
collected data using a telephone-based questionnaire with eight five-point
Likert items and four semi-structured open-ended questions to explore
participants’ perceptions on the structure, content, and illustration of the
manual. The questionnaire also asked participants to rate the overall utility
(out of 10 points) and length of the manual. We used content analysis to
describe main themes from responses to the open-ended interview questions.
Results: Participants’ ratings for structure, content, and illustrations
ranged from 4 to 5 (agree to highly agree), and the median usefulness rating
was 9 (10th percentile: 7, 90th percentile: 10). Main themes from the content
analysis included: ease of use and presentation; health literacy; illustration
utility; health care team delivery; general impression, information support
from hospital to home; emotional and decision-making support; and the novelty
of the manual. Conclusion: The FReSH Start manual was perceived as
comprehensive in content and acceptable for use with older adults post-fall-
related hip fracture. Participants expressed a need for delivery and
explanation of the manual by a health care team member
Nimbus 7 solar backscatter ultraviolet (SBUV) ozone products user's guide
Three ozone tape products from the Solar Backscatter Ultraviolet (SBUV) experiment aboard Nimbus 7 were archived at the National Space Science Data Center. The experiment measures the fraction of incoming radiation backscattered by the Earth's atmosphere at 12 wavelengths. In-flight measurements were used to monitor changes in the instrument sensitivity. Total column ozone is derived by comparing the measurements with calculations of what would be measured for different total ozone amounts. The altitude distribution is retrieved using an optimum statistical technique for the inversion. The estimated initial error in the absolute scale for total ozone is 2 percent, with a 3 percent drift over 8 years. The profile error depends on latitude and height, smallest at 3 to 10 mbar; the drift increases with increasing altitude. Three tape products are described. The High Density SBUV (HDSBUV) tape contains the final derived products - the total ozone and the vertical ozone profile - as well as much detailed diagnostic information generated during the retrieval process. The Compressed Ozone (CPOZ) tape contains only that subset of HDSBUV information, including total ozone and ozone profiles, considered most useful for scientific studies. The Zonal Means Tape (ZMT) contains daily, weekly, monthly and quarterly averages of the derived quantities over 10 deg latitude zones
Fear of Falling Carries Over into Overprotection in Old Age: A Cross-Lagged Panel Analysis
Fear of falling might result in overprotection by one's social environment. In turn, feeling dependent could increase fear of falling. However, the association between fear of falling and perceived overprotection and its temporal order is unknown. This longitudinal study explores this potential mutual longitudinal association. This study presents secondary analyses from a larger trial. We tested the association between fear of falling and perceived overprotection in a cross-lagged path model controlled for falls, health-related quality of life, age, gender, and trial condition. N = 310 participants (M = 70 years, range: 64–92) completed self-reports at Time 1, 7 (Time 2), and 11 weeks (Time 3) after baseline assessment. We found a positive association from fear of falling to perceived overprotection (β = .12, 95% CI[0.02, 0.21], p = .02; β = .10; [0.01, 0.18], p = .03). The reversed cross-lagged paths were not significant. Findings suggest higher fear of falling translates into perceived overprotection, which may in turn increase loss of independence in old age
A global evaluation of streamflow drought characteristics
How drought is characterised depends on the purpose and region of the study and the available data. In case of regional applications or global comparison a standardisation of the methodology to characterise drought is preferable. In this study the threshold level method in combination with three common pooling procedures is applied to daily streamflow series from a wide range of hydrological regimes. Drought deficit characteristics, such as drought duration and deficit volume, are derived, and the methods are evaluated for their applicability for regional studies. Three different pooling procedures are evaluated: the moving-average procedure (MA-procedure), the inter-event time method (IT-method), and the sequent peak algorithm (SPA). The MA-procedure proved to be a flexible approach for the different series, and its parameter, the averaging interval, can easily be optimised for each stream. However, it modifies the discharge series and might introduce dependency between drought events. For the IT-method it is more difficult to find an optimal value for its parameter, the length of the excess period, in particular for flashy streams. The SPA can only be recommended as pooling procedure for the selection of annual maximum series of deficit characteristics and for very low threshold levels to ensure that events occurring shortly after major events are recognized. Furthermore, a frequency analysis of deficit volume and duration is conducted based on partial duration series of drought events. According to extreme value theory, excesses over a certain limit are Generalized Pareto (GP) distributed. It was found that this model indeed performed better than or equally to other distribution models. In general, the GP-model could be used for streams of all regime types. However, for intermittent streams, zero-flow periods should be treated as censored data. For catchments with frost during the winter season, summer and winter droughts have to be analysed separately
On fundamental domains and volumes of hyperbolic Coxeter-Weyl groups
We present a simple method for determining the shape of fundamental domains
of generalized modular groups related to Weyl groups of hyperbolic Kac-Moody
algebras. These domains are given as subsets of certain generalized upper half
planes, on which the Weyl groups act via generalized modular transformations.
Our construction only requires the Cartan matrix of the underlying
finite-dimensional Lie algebra and the associated Coxeter labels as input
information. We present a simple formula for determining the volume of these
fundamental domains. This allows us to re-produce in a simple manner the known
values for these volumes previously obtained by other methods.Comment: v2: to be published in Lett Math Phys (reference added, typo
corrected
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