2,325 research outputs found
Discovery of 11 New T Dwarfs in the Two Micron All-Sky Survey, Including a Possible L/T Transition Binary
We present the discovery of 11 new T dwarfs, found during the course of a
photometric survey for mid-to-late T dwarfs in the 2MASS Point Source Catalog
and from a proper motion selected sample of ultracool dwarfs in the 2MASS
Working Database. Using the NASA Infrared Telescope Facility SpeX spectrograph,
we obtained low-resolution (R~150) spectroscopy, allowing us to derive
near-infrared spectral types of T2-T8. One of these new T dwarfs, 2MASS
J13243559+6358284, was also discovered independently by Metchev et al., in
prep. This object is spectroscopically peculiar and possibly a binary and/or
very young (<300 Myr). We specifically attempted to model the spectrum of this
source as a composite binary to reproduce its peculiar spectral
characteristics. The latest-type object in our sample is a T8 dwarf, 2MASS
J07290002-3954043, now one of the four latest-type T dwarfs known. All 11 T
dwarfs are nearby given their spectrophotometric distance estimates, with 1 T
dwarf within 10 pc and 8 additional T dwarfs within 25 pc, if single. These new
additions increase the 25 pc census of T dwarfs by ~14%. Their proximity offers
an excellent opportunity to probe for companions at closer separations than are
possible for more distant T dwarfs.Comment: 45 pages, 9 figures, 9 tables. Published in AJ. Replacement: Fixed
typos in 3 tables (some reported photometry was from the 2MASS Working
Database instead of the 2MASS All Sky Catalog) and updated Fig.
Use of endocrine and immune responses as predictors of bull sperm motility
Research has shown that peripheral blood cell populations change in response to an immune challenge, and hormone concentrations directly affect sperm characteristics. The objective of this study was to utilize immune responses and hormone concentrations as biomarkers for yearling bull sperm motility. Seventeen Brahman-influenced bulls (mean age 1.1 ± 0.1 yr; body weight 478 ± 38 kg) were administered an intraperitoneal injection of lipopolysaccharide (Salmonella typhimirium 0.7 µg/kg of body weight). Blood was collected 0, 3, 6, 9, and 24 h after LPS injection then analyzed for differential cell count and endocrine concentrations of prolactin, insulin-like growth factor-1 (IGF), and cortisol. Semen was collected using electroejaculation every month for five months then analyzed for motility and morphology characteristics. Hormone concentrations and immune response had an effect on sperm characteristics. Number of sperm was correlated (r \u3e 0.65; P \u3c 0.01) with the IGF to prolactin ratio. Using stepwise regression analysis, we predicted that number of sperm = 172.43 + 12.8 (IGF:prolactin), r2 = 0.43, and progressive sperm motility = -1469.6 + 1.63 (IGF:cortisol) + 14.41 (average temperature during immune challenge), r2 = 0.43. This study showed that endocrine response to stress and activation of the immune system was associated with subsequent sperm motility characteristics. Our results suggest that endocrine and immune responses may be used as biomarkers for sperm motility. Those biomarkers may be useful in selecting replacement bulls
A Candidate Wide Brown Dwarf Binary in the Argus Association: 2MASS J14504216-7841413 and 2MASS J14504113-7841383
[not part of Research Note] We report the discovery of a widely-separated
low-mass binary as a candidate member of the 40 Myr Argus Association.
Resolved imaging and astrometry with 2MASS and LDSS-3 reveal a common proper
motion pair of red sources separated by 4.23''0.11'', with the secondary
roughly one magnitude fainter at , and . Resolved spectroscopy
indicates component types of M8pec and M9pec, the peculiarities arising from
weak Na I and strong VO absorption characteristic of low gravity sources. With
its small proper motion and estimated 7525 pc distance, the BANYAN II tool
indicates a membership probability of 93% in Argus, which would be consistent
with a pair of brown dwarfs of mass 0.04 M separated by
300 AU.Comment: 3 pages, 1 figure, accepted to Research Notes of the AA
Determining the effectiveness of rosemary essential oil on the shelf life of ground beef under different lighting conditions
The objective of this study was to determine the effectiveness of rosemary extract on the shelf life of ground beef patties under different retail display conditions. Ground beef patties were produced from an 85% lean and 15% fat blend purchased from a local grocery retailer, finely ground through a 0.953 cm plate and separated into 151.2 g patties (n=64). Patties were randomly assigned into a control group (no antioxidants added) or a 0.20% concentration rosemary extract group. Patties were individually packaged using polyvinyl chloride overwrap. Antioxidant and control patties were randomly assigned into one of two lighting intensity groups (3000K v. 3500K). Patties were placed in a simulated retail display for 5 d under continuous light emitting diode (LED) lighting and rotated once a day within a multideck display case. Each day of retail display, a patty was removed from each treatment and immediately vacuum packaged and frozen at -20℃. Thiobarbituric acid reactive substances analysis (TBARS) was conducted to evaluate lipid oxidation of the ground beef patties, and color samples were taken each day using the Hunter Lab MiniScan Easy Spectrophotometer.
There was no three-way interaction between display day, antioxidant, and light temperature (P \u3e 0.05) as well as no interaction between display day and light temperature (P \u3e 0.05) and antioxidant and lighting temperature (P \u3e 0.05). There was an interaction observed between antioxidant and day (P \u3c 0.0001). A linear response of lipid oxidation in the control group was noted while the treated antioxidant group remained relatively consistent. Additionally, a main effect of antioxidant type (P \u3c 0.05) and display day (P \u3c 0.05) were observed.
In reference to color spectrometry, L* values presented an interaction between antioxidant and lighting intensity (P = 0.0029). This interaction indicates that lightness can be increased with the use of antioxidants when under higher lighting conditions as opposed to 3000K. A two-way interaction between day and antioxidant (P = 0.0003) was also shown in a* values, indicating that antioxidants create a 1-day separation between the control group on day 4. A similar relationship was found in b* values (P = 0.0008), with day 3 control values measuring at day 4 antioxidant values. Chroma values displayed an interaction between antioxidant and day (P = 0.0008), showing that control values were similar on day 3 as antioxidant levels on day 4, and hue data collected stated similar results (P = 0.0008) There was an interaction observed between antioxidant × day (P \u3c 0.0001). Overall, a higher magnitude of difference was expressed through each progressive day of display, expressing a linear response of lipid oxidation in the control group, while the treated antioxidant group remained relatively consistent.
These interactions conclude that color instability and color degradation can be prevented with the introduction of antioxidants and the reduction of days of retail display. Adding an antioxidant to ground beef does decrease lipid oxidation when compared to ground beef that has not been treated with antioxidants. These data also suggest that antioxidants reduce lipid oxidation regardless of light temperature. As retailers opt for more bright white lights, antioxidants can still be used to successfully extend product shelf life and improve color stability, even in ground product
Dynamical uniform boundedness and the -conjecture
We address the Uniform Boundedness Conjecture of Morton and Silverman in the
case of unicritical polynomials, assuming a generalization of the
-conjecture. For unicritical polynomials of degree at least five, we
require only the standard -conjecture
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