10,081 research outputs found
Discovery of TUG-770: a highly potent free fatty acid receptor 1 (FFA1/GPR40) agonist for treatment of type 2 diabetes
Free fatty acid receptor 1 (FFA1 or GPR40) enhances glucose-stimulated insulin secretion from pancreatic β-cells and currently attracts high interest as a new target for the treatment of type 2 diabetes. We here report the discovery of a highly potent FFA1 agonist with favorable physicochemical and pharmacokinetic properties. The compound efficiently normalizes glucose tolerance in diet-induced obese mice, an effect that is fully sustained after 29 days of chronic dosing
Quasiperiodic Solutions of the Fibre Optics Coupled Nonlinear Schr{\"o}dinger Equations
We consider travelling periodical and quasiperiodical waves in single mode
fibres, with weak birefringence and under the action of cross-phase modulation.
The problem is reduced to the ``1:2:1" integrable case of the two-particle
quartic potential. A general approach for finding elliptic solutions is given.
New solutions which are associated with two-gap Treibich-Verdier potentials are
found. General quasiperiodic solutions are given in terms of two dimensional
theta functions with explicit expressions for frequencies in terms of theta
constants. The reduction of quasiperiodic solutions to elliptic functions is
discussed.Comment: 24 page
The first high-amplitude delta Scuti star in an eclipsing binary system
We report the discovery of the first high-amplitude delta Scuti star in an
eclipsing binary, which we have designated UNSW-V-500. The system is an
Algol-type semi-detached eclipsing binary of maximum brightness V = 12.52 mag.
A best-fitting solution to the binary light curve and two radial velocity
curves is derived using the Wilson-Devinney code. We identify a late A spectral
type primary component of mass 1.49+/-0.02 M_sun and a late K spectral type
secondary of mass 0.33+/-0.02 M_sun, with an inclination of 86.5+/-1.0 degrees,
and a period of 5.3504751+/-0.0000006 d. A Fourier analysis of the residuals
from this solution is performed using PERIOD04 to investigate the delta Scuti
pulsations. We detect a single pulsation frequency of f_1 = 13.621+/-0.015 c/d,
and it appears this is the first overtone radial mode frequency. This system
provides the first opportunity to measure the dynamical mass for a star of this
variable type; previously, masses have been derived from stellar evolution and
pulsation models.Comment: 7 pages, 6 figures, 2 tables, for submission to MNRAS, v2: paper size
change, small typographical changes to abstrac
Identification and Distribution of the Treefrogs Hyla versicolor and Hyla chrysoscelis in Iowa
Historically, the tetraploid and diploid species pair of gray treefrogs, Hyla versicolor and Hyla chrysoscelis, were mapped collectively in Iowa because no macroscopic morphological characteristics useful in recognizing the two species had been found. The present study reports identification and separation of the species by counts of nucleoli in the palpebral membrane of the eye and by measurement of scanning electron micrographs of toepad epithelial projections. Subsequent morphometric data confirm that the two species are morphologically distinct in Iowa but that overlap in characters continues to make macroscopic morphology unreliable for identifying individuals. H. chrysoscelis is distributed sporadically though all but the northeastern quarter of Iowa, while H. versicolor is found roughly southeast of a diagonal line extending from the northeastern to the southwestern corner of the state. A genetically different population appears to reside in Cherokee Co. Iowa
Less Cookbook and More Research! Synthetic Efforts Toward JBIR-94 and JBIR-125: a Student-Designed Research Project in a Sophomore Organic Chemistry Lab
In light of the meaningful learning gains that can be obtained through a genuine research experience, chemistry educators have had a longstanding interest in making teaching labs less “cookbook-like” and more research-driven [1]. With this mindset, we recently restructured our two-semester sophomore organic chemistry lab course to include a synthesis project that was chosen, designed, and carried out by students. This led to progress toward the syntheses of JBIR-94 and JBIR-125, two antioxidative/anticancer natural products that have yet to be assembled through organic chemistry. The major drawback of our course redesign is that it requires close supervision by an instructor or TA experienced in synthetic chemistry and is limited to small class sizes. Its up-front cost is also prohibitive; however, this can be minimized by employing synthetic steps that involve reagents already available on-site. The advantage of this restructuring is encapsulated by highly-positive student feedback and enthusiasm, which led all participating students to continue working on the project after the semester had ended. Exam performance is also discussed. For reference, complete and reproducible experimental details and full copies of student evaluation results are included as Supporting Materials
Occupational balance: What tips the scales for new students?
The open question, ‘What prevents you from reaching occupational balance?’,
was posed within a questionnaire aimed at exploring the meanings of
occupation, health and wellbeing with a cohort of first-year occupational
therapy students during their initial few weeks at university. Their written
responses to the question about occupational balance were analysed and are
discussed in this paper. Not surprisingly, occupational balance appeared to be
achieved by only a few and more by chance than design.
People, time and money factors were identified as the main impediments
to achieving occupational balance, with psychological and emotional pressures
being at the forefront. Interestingly, despite these barriers, the overall
educational benefit of considering the occupational balance question in this
way raised the students’ awareness of its relationship to health and wellbeing.
This increased awareness might have longer-term health benefits, both
personally and professionally, which would be worthy of further research
Nonlinearity-induced conformational instability and dynamics of biopolymers
We propose a simple phenomenological model for describing the conformational
dynamics of biopolymers via the nonlinearity-induced buckling and collapse
(i.e. coiling up) instabilities. Taking into account the coupling between the
internal and mechanical degrees of freedom of a semiflexible biopolymer chain,
we show that self-trapped internal excitations (such as amide-I vibrations in
proteins, base-pair vibrations in DNA, or polarons in proteins) may produce the
buckling and collapse instabilities of an initially straight chain. These
instabilities remain latent in a straight infinitely long chain, because the
bending of such a chain would require an infinite energy. However, they
manifest themselves as soon as we consider more realistic cases and take into
account a finite length of the chain. In this case the nonlinear localized
modes may act as drivers giving impetus to the conformational dynamics of
biopolymers. The buckling instability is responsible, in particular, for the
large-amplitude localized bending waves which accompany the nonlinear modes
propagating along the chain. In the case of the collapse instability, the chain
folds into a compact three-dimensional coil. The viscous damping of the aqueous
environment only slows down the folding of the chain, but does not stop it even
for a large damping. We find that these effects are only weakly affected by the
peculiarities of the interaction potentials, and thus they should be generic
for different models of semiflexible chains carrying nonlinear localized
excitations.Comment: 4 pages (RevTeX) with 5 figures (EPS
Ballistic Limit Equation for Single Wall Titanium
Hypervelocity impact tests and hydrocode simulations were used to determine the ballistic limit equation (BLE) for perforation of a titanium wall, as a function of wall thickness. Two titanium alloys were considered, and separate BLEs were derived for each. Tested wall thicknesses ranged from 0.5mm to 2.0mm. The single-wall damage equation of Cour-Palais [ref. 1] was used to analyze the Ti wall's shielding effectiveness. It was concluded that the Cour-Palais single-wall equation produced a non-conservative prediction of the ballistic limit for the Ti shield. The inaccurate prediction was not a particularly surprising result; the Cour-Palais single-wall BLE contains shield material properties as parameters, but it was formulated only from tests of different aluminum alloys. Single-wall Ti shield tests were run (thicknesses of 2.0 mm, 1.5 mm, 1.0 mm, and 0.5 mm) on Ti 15-3-3-3 material custom cut from rod stock. Hypervelocity impact (HVI) tests were used to establish the failure threshold empirically, using the additional constraint that the damage scales with impact energy, as was indicated by hydrocode simulations. The criterion for shield failure was defined as no detached spall from the shield back surface during HVI. Based on the test results, which confirmed an approximately energy-dependent shield effectiveness, the Cour-Palais equation was modified
The UNSW Extrasolar Planet Search: Methods and First Results from a Field Centred on NGC 6633
We report on the current status of the University of New South Wales
Extrasolar Planet Search project, giving details of the methods we use to
obtain millimagnitude precision photometry using the 0.5m Automated Patrol
Telescope. We use a novel observing technique to optimally broaden the PSF and
thus largely eliminate photometric noise due to intra-pixel sensitivity
variations on the CCD. We have observed 8 crowded Galactic fields using this
technique during 2003 and 2004. Our analysis of the first of these fields
(centred on the open cluster NGC 6633) has yielded 49 variable stars and 4
shallow transit candidates. Follow-up observations of these candidates have
identified them as eclipsing binary systems. We use a detailed simulation of
our observations to estimate our sensitivity to short-period planets, and to
select a new observing strategy to maximise the number of planets detected.Comment: 16 pages, 9 figures, version published in MNRAS Updated figures,
references, and additional discussion in section
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