12,169 research outputs found
Six Peaks Visible in the Redshift Distribution of 46,400 SDSS Quasars Agree with the Preferred Redshifts Predicted by the Decreasing Intrinsic Redshift Model
The redshift distribution of all 46,400 quasars in the Sloan Digital Sky
Survey (SDSS) Quasar Catalog III, Third Data Release, is examined. Six Peaks
that fall within the redshift window below z = 4, are visible. Their positions
agree with the preferred redshift values predicted by the decreasing intrinsic
redshift (DIR) model, even though this model was derived using completely
independent evidence. A power spectrum analysis of the full dataset confirms
the presence of a single, significant power peak at the expected redshift
period. Power peaks with the predicted period are also obtained when the upper
and lower halves of the redshift distribution are examined separately. The
periodicity detected is in linear z, as opposed to log(1+z). Because the peaks
in the SDSS quasar redshift distribution agree well with the preferred
redshifts predicted by the intrinsic redshift relation, we conclude that this
relation, and the peaks in the redshift distribution, likely both have the same
origin, and this may be intrinsic redshifts, or a common selection effect.
However, because of the way the intrinsic redshift relation was determined it
seems unlikely that one selection effect could have been responsible for both.Comment: 12 pages, 12 figure, accepted for publication in the Astrophysical
Journa
Male chicken thigh meat quality from fast and slow growing breeds from an organic free-range system
Significant effects of Genotype and Age on several of the technological meat quality attributes measured were found. In general, the meat from fast growing birds (JA) was darker, more tender, had a higher water-binding but a higher cooking loss. Birds with a higher age at slaughter was more red, less tender and had a higher cooking loss. Regarding the protein concentration of the feed, no significant effects could be found on meat quality attributes, however a high protein concentration in the feed showed a tendency towards more tender meat
Bayesian Forecast Combination for VAR Models
We consider forecast combination and, indirectly, model selection for VAR models when there is uncertainty about which variables to include in the model in addition to the forecast variables. The key dierence from traditional Bayesian variable selection is that we also allow for uncertainty regarding which endogenous variables to include in the model. That is, all models include the forecast variables, but may otherwise have diering sets of endogenous variables. This is a dicult problem to tackle with a traditional Bayesian approach. Our solution is to focus on the forecasting performance for the variables of interest and we construct model weights from the predictive likelihood of the forecast variables. The procedure is evaluated in a small simulation study and found to perform competitively in applications to real world data.Bayesian model averaging; Predictive likelihood; GDP forecasts
Mn induced modifications of Ga 3d photoemission from (Ga, Mn)As: evidence for long range effects
Using synchrotron based photoemission, we have investigated the Mn-induced
changes in Ga 3d core level spectra from as-grown . Although Mn is located in Ga substitutional sites, and does
therefore not have any Ga nearest neighbours, the impact of Mn on the Ga core
level spectra is pronounced even at Mn concentrations in the range of 0.5%. The
analysis shows that each Mn atom affects a volume corresponding to a sphere
with around 1.4 nm diameter.Comment: Submitted to Physical Review B, Brief Repor
Physical activity, muscle function, falls and fractures
STUDY DESIGN: A thematic review. OBJECTIVES: To evaluate if physical activity enhances muscle strength, improves balance, and reduces the fall frequency and the fracture incidence. BACKGROUND: One of the major medical problems of today is the increasing incidence of fragility fractures. Muscle strength and fall is one of the major determinants of a fracture. If physical activity could increase muscle strength, improve balance and reduce the fall frequency, then training could be recommended as prevention for fractures. METHODS: The review used Medline (Pub Med) and the search words exercise, physical activity, muscle strength, balance, falls, fractures. Randomized controlled trials (RCT) were predominantly included, although this not is a systematic review. RESULTS: The evidence that physical activity modifies the risk factors for fall is compelling, although RCT with fractures as end point are lacking. Physical activity is associated with improved muscle strength, co-ordination and balance. Physical training increases muscle strength also in octogenarians by up to 200%, i.e. a much more pronounced effect than the corresponding increase in muscle volume or bone mass. There is also evidence that physical activity decreases the actual number of falls. Observational cohort and case-control studies imply that physical activity is associated with reduced hip fracture risk. If exercise reduces the number of vertebral fractures and other fragility fractures are less evaluated. CONCLUSIONS: Physical activity in older ages can be recommended to improve muscle strength and balance, to reduce the risk to fall and fractures, although the highest level of evidence - RCT with fracture as endpoint - is lacking
Second order statistics of NLOS indoor MIMO channels based on 5.2 GHz measurements
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