1,002 research outputs found
Sizes of Voids as a test for Dark Matter Models
We use the void probability statistics to study the redshift-space galaxy
distribution as described by a volume-limited subsample of the Perseus-Pisces
survey. We compare the results with the same analysis realized on artificial
samples, extracted from high-resolution N-body simulations by reproducing the
observational biases of the real data set. Simulations are run for the
Cold+HotDM model (CHDM) and for unbiased and biased (b=1.5) CDM models in a 50
Mpc/h box. We identify galaxies as residing in peaks of the evolved density
field. We fragment overmerged structures into individual galaxies so as to
reproduce both the correct luminosity function (after assuming M/ L values for
the resulting galaxy groups) and the two-point correlation function. Our main
result is that a void-probability function (VPF) from the standard CHDM model
with fractions 60% cold, 30% hot, 10% barions, exceeds the observational VPF
with a high confidence level. CDM models produce smaller VPF independent of the
biasing parameter. We verify the robustness of this result against changing the
observer position in the simulations and the galaxy identification in the
evolved density field.Comment: 15 pages, postscrip
The HI Mass Function and Velocity Width Function of Void Galaxies in the Arecibo Legacy Fast ALFA Survey
We measure the HI mass function (HIMF) and velocity width function (WF)
across environments over a range of masses ,
and profile widths , using a catalog of
~7,300 HI-selected galaxies from the ALFALFA Survey, located in the region of
sky where ALFALFA and SDSS (Data Release 7) North overlap. We divide our galaxy
sample into those that reside in large-scale voids (void galaxies) and those
that live in denser regions (wall galaxies). We find the void HIMF to be well
fit by a Schechter function with normalization
, characteristic mass
, and low-mass-end slope
. Similarly, for wall galaxies, we find best-fitting
parameters ,
, and . We
conclude that void galaxies typically have slightly lower HI masses than their
non-void counterparts, which is in agreement with the dark matter halo mass
function shift in voids assuming a simple relationship between DM mass and HI
mass. We also find that the low-mass slope of the void HIMF is similar to that
of the wall HIMF suggesting that there is either no excess of low-mass galaxies
in voids or there is an abundance of intermediate HI mass galaxies. We fit a
modified Schechter function to the ALFALFA void WF and determine its
best-fitting parameters to be ,
, and high-width slope
. For wall galaxies, the WF parameters are:
, ,
and . Because of large uncertainties on
the void and wall width functions, we cannot conclude whether the WF is
dependent on the environment.Comment: Accepted for publication at MNRAS, 14 pages, 12 figure
Influence of Cooking Conditions on Nutritional Properties and Sensory Characteristics Interpreted by E-Senses: Case-Study on Selected Vegetables
This study investigates the effects of three cooking methods (boiling, steaming and microwaving) on the nutritional and physical properties of cauliflowers, carrots and sweet potatoes; e-senses were applied to interpret the sensory characteristics according to physico-chemical aspects. The nutritional quality was evaluated by determining the concentrations of key components and the antioxidant activity; e-sense data, combined with texture parameters, were processed by a principal component analysis. The cooking method and time significantly influenced the quality of the three products. Boiling, which detrimentally affected ascorbic acid, total phenolic concentration and antioxidant activity, enhanced carotene accessibility. Steaming produced losses in ascorbic acid, increasing total phenolics and carotenoids. Microwaving resulted in minor changes in ascorbic acid concentrations, preserved carotenoids and increased total phenolics. The nutritional quality was better preserved or enhanced using shorter cooking times. The elaboration of the data collected by the e-senses showed a clear evolution according to the cooking method and time. The results helped to determine the cooking method that best preserves the nutritional properties of the vegetables, highlighting the applicability of rapid instrumental methods to interpret the evolution of sensory characteristics
Evolution of physicochemical, morphological and aromatic characteristics of Italian PDO dry-cured hams during processing
The aim of this work was to follow the evolution of physicochemical (dry matter, NaCl concentration, pH, water activity), morphological (image analysis) and aromatic (e-nose) characteristics of the three main Italian PDOs during processing, from slaughtering to end of ripening. Main phenomena distinguishing the PDOs are NaCl concentration increase, which is higher in Toscano than in Parma and San Daniele hams, starting from the salting phase. Water activity values decrease during processing, and the lowest values are detected in Toscano ham. Changes in morphological parameters (area, shape) and in color progressively occur during processing and are more pronounced in Toscano ham. A clear evolution of aroma of the three PDOs has been observed by e-nose, and the complexity of the aromatic profile of the ripened hams is clearly highlighted
High-intensity interval training: optimizing oxygen consumption and time to exhaustion taking advantage of the exponential reconstitution behaviour of D’
Purpose: Accumulating the time near maximum aerobic power (V ˙ O 2max) is considered to be the most effective way to improve aerobic capacity. The aims of this study were: (1) to verify whether postponing the first recovery interval improves time to exhaustion during a high-intensity interval training (HIIT) test, and (2) to verify whether a HIIT protocol with decreasing interval duration (HIDIT) is more effective in accumulating time near V ˙ O 2max compared with two classical protocols with short intervals (SIHIIT) and long intervals (LIHIIT). Methods: Nine active males (35 ± 11 years, V ˙ O 2max 52 ± 5 mL·min−1·kg−1) performed a graded exercise test on an athletic track. Critical velocity and D’ were estimated from three to five high-intensity trials to exhaustion. Then, the subjects performed three trials with a single recovery interval after 30 s (Rec30s), after 3 min (Rec3min) and after exhaustion (RecTlim) to verify whether postponing the first recovery interval enhances the time to exhaustion. Finally, the subjects performed the three HIIT protocols mentioned above. Results: The time to exhaustion was significantly greater in RecTlim (464 ± 67 s) than in Rec3min (388 ± 48 s) (p 0.0001). Additionally, it was significantly greater in Rec3min than in Rec30s (p = 0.0247). Furthermore, the time accumulated near V ˙ O 2max was significantly longer in HIDIT (998 ± 129 s) than in SIHIIT (678 ± 116 s) (p = 0.003) and LIHIIT (673 ± 115 s) (p < 0.031). Conclusions: During the trials, postponing the first recovery interval was effective in improving the time to exhaustion. Moreover, HIDIT was effective in prolonging the time near V ˙ O 2max
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