433 research outputs found
Determination of the Hubble Constant Using a Two-Parameter Luminosity Correction for Type Ia Supernovae
In this paper, we make a comprehensive determination of the Hubble constant
by using two parameters - the B-V color and the rate of decline - to simultaneously standardize the luminosities of all nearby
Cepheid-calibrated type Ia supernovae (SNe Ia) and those of a larger, more
distant sample of 29 SNe Ia. Each group is treated in as similar a manner as
possible in order to avoid systematic effects. A simultaneous
minimization yields a standardized absolute luminosity of the
Cepheid-calibrated supernovae as well as the Hubble constant obtained from the
more distant sample. We find and a standardized
absolute magnitude of -19.46. The sensitivity of to a metallicity
dependence of the Cepheid-determined distances is investigated. The total
uncertainty , dominated by uncertainties in the primary Cepheid
distance indicator, is estimated to be 5 km/s Mpc^{-1}.Comment: To appear in Ap
The Effects of Strengthened IPR Regimes on the Plant Breeding Sector in Developing Countries
This paper analyzes the effect of intellectual property rights (IPR) regimes on the plant breeding sector in developing countries. Most of these countries have implemented a system of plant variety protection (PVP), or are in the process of doing so, generally as part of their obligations under the Agreement on Trade Related Aspects of Intellectual Property (TRIPS) of the World Trade Organization (WTO). This paper presents the results of research on the initial effects of IPRs on the plant breeding sector in five case study countries (China, Colombia, India, Kenya and Uganda). Three of the countries have PVP systems in place and the other two are in the process of either developing or implementing legislation. But the ease of implementing PVP seems to have been overestimated. Opportunities to minimize the transaction costs of acquiring and enforcing rights are being missed. Detailed interviews with both domestic and international seed companies suggest that PVP can not be expected to initiate the development of a commercial seed sector. But a well functioning system can play a role in stimulating further development of the sector, although a measured approach to increasing the scope of protection will probably better balance interests than rapid adoption standards of industrialized countries. The results also highlight the particular challenges facing national agricultural research institutes in determining how to best make use of IPRs, such as PVP, particularly given broader changes in publicly-financed agricultural research.Crop Production/Industries, L3, O3, Q16,
Recommended from our members
Purpose in Life and Conscientiousness Protect Against the Development of Suicidal Ideation in U.S. Military Veterans With PTSD and MDD: Results From the National Health and Resilience in Veterans Study.
Background:Although several studies have examined risk factors for suicidal ideation among veterans, little is known about risk and protective factors for suicidal ideation in high-risk veteran samples. Thus, this study examined a broad range of risk and protective factors associated with the development of suicidal ideation in a high-risk sample of U.S. veterans who screened positive for current posttraumatic stress disorder (PTSD) and/or major depressive disorder (MDD). Methods:Data were analyzed from the National Health and Resilience in Veterans Study, a nationally representative, prospective cohort study of U.S. veterans. Veterans completed self-report measures to screen for PTSD and MDD and to assess for risk and protective factors. The sample included 222 veterans with PTSD and/or MDD who did not endorse suicidal ideation at baseline and completed at least one assessment over a seven-year follow-up period. A multivariable binary logistic regression analysis was conducted to examine baseline factors associated with incident suicidal ideation. Results:Nearly one in three (27.1%) of veterans with PTSD and/or MDD developed suicidal ideation over the seven-year follow-up period. Non-Caucasian race and lower scores on measures of purpose in life, conscientiousness, and frequency of religious service attendance were independently associated with incident suicidal ideation. Lower purpose in life (52.3%) and conscientiousness (33.2%) explained the vast majority of variance in incident suicidal ideation. Conclusion:Nearly 30% of veterans with PTSD and/or MDD who did not endorse suicidal ideation at baseline developed suicidal ideation over a seven-year period. Prevention and treatment efforts designed to bolster purpose in life and conscientiousness may help mitigate risk for suicidal ideation in this high-risk population
Comprehensive Cause Analysis Of A Coupling Failure Induced By Torsional Oscillations In A Variable Speed Motor
LecturePg. 17-24The analysis of two compressor train coupling failures that were caused by a subsynchronous torsional resonance is discussed. These torsional failures manifested themselves as fatigue cracks that propagated across the coupling spacers at a classic 45 degree orientation. Analysis of the failures included a long term program of measuring actual online coupling stresses, identifying the source of the infrequent subsynchronous torsional oscillations, a finite element analysis of the coupling, and a fracture mechanics analysis which, along with measured stresses, explained the failures
Declining Recruitment and Growth of Shovelnose Sturgeon in the Middle Mississippi River: Implications for Conservation
To determine how populations of shovelnose sturgeon Scaphirhynchus platorynchus are changing and may respond to poor environmental conditions, current commercial harvest of black-egg (sexually mature) females, and incidental mortality of males, we require annual information about sex-specific age structure as it relates to the recruitment of new cohorts. We sampled shovelnose sturgeon by use of gill nets (5-cm bar mesh) monthly during 2002-2006 in the Middle Mississippi River between Cairo, Illinois, and St. Louis, Missouri. We compared patterns of size and age structure over time and projected age structure and population size into the future. Sex ratio in 2005-2006 was 1.14:1.00 (416 males and 363 females; P = 0.06), deviating from the 1:1 ratio that occurred in 2002-2003. Annual mortality increased from 37% in 2002-2003 to 44% by 2005-2006. Female shovelnose sturgeon were larger than males. Across years, the population shifted toward longer, older fish, and growth in length declined. Recruitment declined through time (29% per year). If these trends continue and if immigration from nonharvested populations is limited, population density may decline by an order of magnitude within one decade. Under current conditions, resilience to harvest and environmental perturbations is probably limited
An IR Search for Extinguished Supernovae in Starburst Galaxies
IR and Radio band observations of heavily extinguished regions in starburst
galaxies suggest a very high SN rate associated with such regions. Optically
measured supernova (SN) rates may therefore underestimate the total SN rate by
factors of up to 10, due to the high extinction to SNe in starburst regions.
The IR/radio SN rates come from a variety of indirect means, however, which
suffer from model dependence and other problems.
We describe a direct measurement of the SN rate from a regular patrol of
starburst galaxies done with K' band imaging to minimize the effects of
extinction. A collection of K' measurements of core-collapse SNe near maximum
light is presented. Results of a preliminary SN search using the MIRC camera at
the Wyoming IR Observatory (WIRO), and an improved search using the ORCA optics
are described. A monthly patrol of starburst galaxies within 25 Mpc should
yield 1.6 - 9.6 SNe/year. Our MIRC search with low-resolution (2.2" pixels)
failed to find extinguished SNe, limiting the SN rate outside the nucleus (at >
15" radius) to less than 3.8 Supernova Rate Units (SRU or SNe/century/10^10
L(solar); 90% confidence). The MIRC camera had insufficient resolution to
search nuclear starburst regions, where SN activity is concentrated, explaining
why we found no heavily obscured SNe. We conclude that high-resolution, small
field SN searches in starburst nuclei are more productive than low resolution,
large-field searches, even for our large galaxies. With our ORCA
high-resolution optics, we could limit the total SN rate to < 1.3 SRU at 90%
confidence in 3 years of observations, lower than the most pessimistic
estimate.Comment: AJ Submitted 1998 Dec. 13. View figures and download all as one file
at http://panisse.lbl.gov/public/bruce/irs
Maturation and Reproduction of Shovelnose Sturgeon in the Middle Mississippi River
Shovelnose sturgeon Scaphirhynchus platorynchus in the middle Mississippi River provide one of the last commercially viable sturgeon fisheries in the world, yet their maturation and reproduction have not been linked. During 2005 and 2006, we sampled adult and age-0 shovelnose sturgeon to link age at maturation, the timing and periodicity of spawning, age-0 sturgeon production, and the resulting age-0 growth rates. Age at maturity was later than previous estimates, the minimum age of first maturation being 8 years for males and 9 years for females. Total egg count was slightly lower than previously reported (mean = 29,573 per female; SE = 2,472). Males and females typically spawned every 2 and 3 years, respectively. Peaks in mature fish coincided with rising river stages and water temperatures at which shovelnose sturgeon probably spawn. Peaks in spent adults followed. Age-0 shovelnose sturgeon occurred during June and July 2005 and May and June 2006, confirming successful spawning. Age-0 sturgeon grew between 0.69 and 1.69 mm total length/d; four distinct weekly cohorts occurred each year. During fall 2006, females contained ripe eggs, males were milting, and a single age-0 sturgeon (total length = 55 mm) was captured, suggesting that shovelnose sturgeon spawn during fall as well as spring. Management must consider the protracted nature of spawning within seasons as well as differences in spawning activity between seasons
Hypothetical membrane mechanisms in essential tremor
This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens
- …