5,750 research outputs found
Extent and Characteristics of Retail Fresh Beef Branding
Limited information exists regarding the extent and characteristics of branded fresh beef. Retail package data from a sample of grocery stores in three metropolitan areas enabled determining the extent of branded beef for ground beef, roasts, and steaks. Logit models identified factors affecting the probability of beef products being branded, and the probability of beef products carrying specific types of brands compared with store brands and generic (unbranded) beef. The extent of branded beef and type of brand both varied by store type, specific product, quality designation, package type, and presence of special labeling.Marketing,
Fundamental study of transpiration cooling
Isothermal and non-isothermal pressure drop data and heat transfer data generated on porous 304L stainless steel wire forms, sintered spherical stainless steel powder, and sintered spherical OFHC copper powder are reported and correlated. Pressure drop data was collected over a temperature range from 500 R to 2000 R and heat transfer data collected over a heat flux range from 5 to 15 BTU/in2/sec. It was found that flow data could be correlated independently of transpirant temperature and type (i.e., H2, N2). It was also found that no simple relation between heat transfer coefficient and specimen porosity was obtainable
STM Studies of Synthetic Peptide Monolayers
We have used scanning probe microscopy to investigate self-assembled
monolayers of chemically synthesized peptides. We find that the peptides form a
dense uniform monolayer, above which is found a sparse additional layer. Using
scanning tunneling microscopy, submolecular resolution can be obtained,
revealing the alpha helices which constitute the peptide. The nature of the
images is not significantly affected by the incorporation of redox cofactors
(hemes) in the peptides.Comment: 4 pages, 3 figures (4 gifs); to appear in the Proceedings of the
XIIth Int. Winterschool on Electronic Properties of Novel Materials
"Molecular Nanostructures", Kirchberg/Tyrol, Febr. 199
Nurse telephone triage for same day appointments in general practice: multiple interrupted time series trial of effect on workload and costs
OBJECTIVE: To compare the workloads of general practitioners and nurses and costs of patient care for nurse telephone triage and standard management of requests for same day appointments in routine primary care. DESIGN: Multiple interrupted time series using sequential introduction of experimental triage system in different sites with repeated measures taken one week in every month for 12 months. SETTING: Three primary care sites in York. Participants: 4685 patients: 1233 in standard management, 3452 in the triage system. All patients requesting same day appointments during study weeks were included in the trial. MAIN OUTCOME MEASURES: Type of consultation (telephone, appointment, or visit), time taken for consultation, presenting complaints, use of services during the month after same day contact, and costs of drugs and same day, follow up, and emergency care. RESULTS: The triage system reduced appointments with general practitioner by 29-44%. Compared with standard management, the triage system had a relative risk (95% confidence interval) of 0.85 (0.72 to 1.00) for home visits, 2.41 (2.08 to 2.80) for telephone care, and 3.79 (3.21 to 4.48) for nurse care. Mean overall time in the triage system was 1.70 minutes longer, but mean general practitioner time was reduced by 2.45 minutes. Routine appointments and nursing time increased, as did out of hours and accident and emergency attendance. Costs did not differ significantly between standard management and triage: mean difference £1.48 more per patient for triage (95% confidence interval -0.19 to 3.15). CONCLUSIONS: Triage reduced the number of same day appointments with general practitioners but resulted in busier routine surgeries, increased nursing time, and a small but significant increase in out of hours and accident and emergency attendance. Consequently, triage does not reduce overall costs per patient for managing same day appointments
Clues to the nature of dark matter from first galaxies
We use thirty-eight high-resolution simulations of galaxy formation between
redshift 10 and 5 to study the impact of a 3 keV warm dark matter (WDM)
candidate on the high-redshift Universe. We focus our attention on the stellar
mass function and the global star formation rate and consider the consequences
for reionization, namely the neutral hydrogen fraction evolution and the
electron scattering optical depth. We find that three different effects
contribute to differentiate warm and cold dark matter (CDM) predictions: WDM
suppresses the number of haloes with mass less than few M; at
a fixed halo mass, WDM produces fewer stars than CDM; and finally at halo
masses below M, WDM has a larger fraction of dark haloes than
CDM post-reionization. These three effects combine to produce a lower stellar
mass function in WDM for galaxies with stellar masses at and below
M. For , the global star formation density is lower by a
factor of two in the WDM scenario, and for a fixed escape fraction, the
fraction of neutral hydrogen is higher by 0.3 at . This latter
quantity can be partially reconciled with CDM and observations only by
increasing the escape fraction from 23 per cent to 34 per cent. Overall, our
study shows that galaxy formation simulations at high redshift are a key tool
to differentiate between dark matter candidates given a model for baryonic
physics.Comment: 11 pages, 8 figures, submitted to MNRA
NIHAO XX: The impact of the star formation threshold on the cusp-core transformation of cold dark matter haloes
We use cosmological hydrodynamical galaxy formation simulations from the
NIHAO project to investigate the impact of the threshold for star formation on
the response of the dark matter (DM) halo to baryonic processes. The fiducial
NIHAO threshold, , results in strong expansion of the DM
halo in galaxies with stellar masses in the range . We find that lower thresholds such as (as employed
by the EAGLE/APOSTLE and Illustris/AURIGA projects) do not result in
significant halo expansion at any mass scale. Halo expansion driven by
supernova feedback requires significant fluctuations in the local gas fraction
on sub-dynamical times (i.e., < 50 Myr at galaxy half-light radii), which are
themselves caused by variability in the star formation rate. At one per cent of
the virial radius, simulations with have gas fractions of
and variations of , while simulations have order of
magnitude lower gas fractions and hence do not expand the halo. The observed DM
circular velocities of nearby dwarf galaxies are inconsistent with CDM
simulations with and , but in reasonable agreement with .
Star formation rates are more variable for higher , lower galaxy masses, and
when star formation is measured on shorter time scales. For example,
simulations with have up to 0.4 dex higher scatter in specific star
formation rates than simulations with . Thus observationally
constraining the sub-grid model for star formation, and hence the nature of DM,
should be possible in the near future.Comment: 18 pages, 13 figures, accepted to MNRA
The edge of galaxy formation III: The effects of warm dark matter on Milky Way satellites and field dwarfs
In this third paper of the series, we investigate the effects of warm dark
matter with a particle mass of on the smallest
galaxies in our Universe. We present a sample of 21 hydrodynamical cosmological
simulations of dwarf galaxies and 20 simulations of satellite-host galaxy
interaction that we performed both in a Cold Dark Matter (CDM) and Warm Dark
Matter (WDM) scenario. In the WDM simulations, we observe a higher critical
mass for the onset of star formation. Structure growth is delayed in WDM, as a
result WDM haloes have a stellar population on average two Gyrs younger than
their CDM counterparts. Nevertheless, despite this delayed star formation, CDM
and WDM galaxies are both able to reproduce the observed scaling relations for
velocity dispersion, stellar mass, size, and metallicity at . WDM
satellite haloes in a Milky Way mass host are more susceptible to tidal
stripping due to their lower concentrations, but their galaxies can even
survive longer than the CDM counterparts if they live in a dark matter halo
with a steeper central slope. In agreement with our previous CDM satellite
study we observe a steepening of the WDM satellites' central dark matter
density slope due to stripping. The difference in the average stellar age for
satellite galaxies, between CDM and WDM, could be used in the future for
disentangling these two models.Comment: 10 pages, 11 figures, accepted for publication on MNRA
Magnetically-controlled velocity selection in a cold atom sample using stimulated Raman transitions
We observe velocity-selective two-photon resonances in a cold atom cloud in
the presence of a magnetic field. We use these resonances to demonstrate a
simple magnetometer with sub-mG resolution. The technique is particularly
useful for zeroing the magnetic field and does not require any additional laser
frequencies than are already used for standard magneto-optical traps. We verify
the effects using Faraday rotation spectroscopy.Comment: 5 pages, 6 figure
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