783 research outputs found
On higher congruences between cusp forms and Eisenstein series
In this paper we present several finite families of congruences between cusp
forms and Eisenstein series of higher weights at powers of prime ideals. We
formulate a conjecture which describes properties of the prime ideals and their
relation to the weights. We check the validity of the conjecture on several
numerical examples.Comment: 20 page
Randomized Controlled Trial of the Effectiveness of Genetic Counseling and a Distance, Computer-Based, Lifestyle Intervention Program for Adult Offspring of Patients with Type 2 Diabetes: Background, Study Protocol, and Baseline Patient Characteristics
Relatives of type 2 diabetic patients are at a high risk of developing type 2 diabetes and should be regarded as target of intervention for diabetes prevention. However, it is usually hard to motivate them to implement preventive lifestyle changes, because of lack of opportunity to take advises from medical professionals, inadequate risk perception, and low priority for preventive behavior. Prevention strategy for them therefore should be highly acceptable and suited for them. The parallel, three-group trial is now being conducted to investigate the effects of genetic counseling and/or a computerized behavioral program on the prevention of type 2 diabetes in that population. The preventive strategies used in this study could provide a novel solution to the numbers of genetically high-risk individuals, if found to be effective. The objective of this paper is to describe the background, protocol, and baseline patient characteristics of the trial
Discovery of interstellar mercapto radicals (SH) with the GREAT instrument on SOFIA
We report the first detection of interstellar mercapto radicals, obtained
along the sight-line to the submillimeter continuum source W49N. We have used
the GREAT instrument on SOFIA to observe the 1383 GHz Doublet Pi 3/2 J = 5/2 -
3/2 lambda doublet in the upper sideband of the L1 receiver. The resultant
spectrum reveals SH absorption in material local to W49N, as well as in
foreground gas, unassociated with W49N, that is located along the sight-line.
For the foreground material at velocities in the range 37 - 44 km/s with
respect to the local standard of rest, we infer a total SH column density ~ 2.6
E+12 cm-2, corresponding to an abundance of ~ 7 E-9 relative to H2, and
yielding an SH/H2S abundance ratio ~ 0.13. The observed SH/H2S abundance ratio
is much smaller than that predicted by standard models for the production of SH
and H2S in turbulent dissipation regions and shocks, and suggests that the
endothermic neutral-neutral reaction SH + H2 -> H2S + H must be enhanced along
with the ion-neutral reactions believed to produce CH+ and SH+ in diffuse
molecular clouds.Comment: Accepted for publication in Astronomy and Astrophysics (SOFIA/GREAT
special issue
Linear approaches to intramolecular Förster Resonance Energy Transfer probe measurements for quantitative modeling
Numerous unimolecular, genetically-encoded Forster Resonance Energy Transfer (FRET) probes for monitoring biochemical activities in live cells have been developed over the past decade. As these probes allow for collection of high frequency, spatially resolved data on signaling events in live cells and tissues, they are an attractive technology for obtaining data to develop quantitative, mathematical models of spatiotemporal signaling dynamics. However, to be useful for such purposes the observed FRET from such probes should be related to a biological quantity of interest through a defined mathematical relationship, which is straightforward when this relationship is linear, and can be difficult otherwise. First, we show that only in rare circumstances is the observed FRET linearly proportional to a biochemical activity. Therefore in most cases FRET measurements should only be compared either to explicitly modeled probes or to concentrations of products of the biochemical activity, but not to activities themselves. Importantly, we find that FRET measured by standard intensity-based, ratiometric methods is inherently non-linear with respect to the fraction of probes undergoing FRET. Alternatively, we find that quantifying FRET either via (1) fluorescence lifetime imaging (FLIM) or (2) ratiometric methods where the donor emission intensity is divided by the directly-excited acceptor emission intensity (denoted R<sub>alt</sub>) is linear with respect to the fraction of probes undergoing FRET. This linearity property allows one to calculate the fraction of active probes based on the FRET measurement. Thus, our results suggest that either FLIM or ratiometric methods based on R<sub>alt</sub> are the preferred techniques for obtaining quantitative data from FRET probe experiments for mathematical modeling purpose
VLA HI Zeeman Observations Toward the W49 Complex
We report VLA HI Zeeman observations toward the W49A star-forming region and
the SNR W49B. Line of sight magnetic fields (Blos) of 60 to 300 muG at 25"
resolution were detected toward W49A at velocities of ~4 and ~7 km/s. The Blos
values measured toward W49A show a significant increase in field strength with
higher resolution especially for the ~4 km/s HI gas. The HI gas in the velocity
range -5 to 25 km/s toward W49A shows good agreement both kinematically and
spatially with molecular emission intrinsically associated with W49A. Based on
comparisons with molecular data toward W49A, we suggest that the 4 km/s HI gas
is directly associated with the northern part of the HII region ring, while the
7 km/s HI gas seems to originate in a lower density halo surrounding W49A. We
estimate that the W49A North core is significantly subvirial, and that the
total kinetic +magnetic energies amount to less than 1/3 of the total W49A
North gravitational energy. These magnetic field results suggest that W49A
North is unstable to overall gravitational collapse in agreement with evidence
that the halo is collapsing onto the W49A North ring of HII regions.
The majority of the HI column density toward W49B comes from Sagittarius Arm
clouds along the line of sight at ~40 km/s and ~60 km/s. No significant
magnetic fields were detected toward W49B. Comparison of the spectral
distribution of HI gas toward W49A and W49B suggests that evidence placing W49B
3 kpc closer to the sun (i.e. at 8 kpc) than W49A is quite weak.Comment: Accepted to ApJ (March 2001), 39 pages and 16 figures. Higher
resolution images for Figs. 1,3,4,5,7 and 9 can be obtained from
http://www.aoc.nrao.edu/~cbroga
mKikGR, a Monomeric Photoswitchable Fluorescent Protein
The recent demonstration and utilization of fluorescent proteins whose fluorescence can be switched on and off has greatly expanded the toolkit of molecular and cell biology. These photoswitchable proteins have facilitated the characterization of specifically tagged molecular species in the cell and have enabled fluorescence imaging of intracellular structures with a resolution far below the classical diffraction limit of light. Applications are limited, however, by the fast photobleaching, slow photoswitching, and oligomerization typical for photoswitchable proteins currently available. Here, we report the molecular cloning and spectroscopic characterization of mKikGR, a monomeric version of the previously reported KikGR that displays high photostability and switching rates. Furthermore, we present single-molecule imaging experiments that demonstrate that individual mKikGR proteins can be localized with a precision of better than 10 nanometers, suggesting their suitability for super-resolution imaging
A practical device for pinpoint delivery of molecules into multiple neurons in culture
We have developed a device for pinpoint delivery of chemicals, proteins, and nucleic acids into cultured cells. The principle underlying the technique is the flow of molecules from the culture medium into cells through a rupture in the plasma membrane made by a needle puncture. DNA transfection is achieved by stabbing the needle tip into the nucleus. The CellBee device can be attached to any inverted microscope, and molecular delivery can be coupled with conventional live cell imaging. Because the position of the needle relative to the targeted cultured cells is computer-controlled, efficient delivery of molecules such as rhodamine into as many as 100 HeLa cells can be completed in 10 min. Moreover, specific target cells within a single dish can be transfected with multiple DNA constructs by simple changes of culture medium containing different plasmids. In addition, the nano-sized needle tip enables gentle molecular delivery, minimizing cell damage. This method permits DNA transfection into specific hippocampal neurons without disturbing neuronal circuitry established in culture
Vaccination against GIP for the Treatment of Obesity
BACKGROUND: According to the WHO, more than 1 billion people worldwide are overweight and at risk of developing chronic illnesses, including cardiovascular disease, type 2 diabetes, hypertension and stroke. Current therapies show limited efficacy and are often associated with unpleasant side-effect profiles, hence there is a medical need for new therapeutic interventions in the field of obesity. Gastric inhibitory peptide (GIP, also known as glucose-dependent insulinotropic polypeptide) has recently been postulated to link over-nutrition with obesity. In fact GIP receptor-deficient mice (GIPR(-/-)) were shown to be completely protected from diet-induced obesity. Thus, disrupting GIP signaling represents a promising novel therapeutic strategy for the treatment of obesity. METHODOLOGY/PRINCIPAL FINDINGS: In order to block GIP signaling we chose an active vaccination approach using GIP peptides covalently attached to virus-like particles (VLP-GIP). Vaccination of mice with VLP-GIP induced high titers of specific antibodies and efficiently reduced body weight gain in animals fed a high fat diet. The reduction in body weight gain could be attributed to reduced accumulation of fat. Moreover, increased weight loss was observed in obese mice vaccinated with VLP-GIP. Importantly, despite the incretin action of GIP, VLP-GIP-treated mice did not show signs of glucose intolerance. CONCLUSIONS/SIGNIFICANCE: This study shows that vaccination against GIP was safe and effective. Thus active vaccination may represent a novel, long-lasting treatment for obesity. However further preclinical safety/toxicology studies will be required before the therapeutic concept can be addressed in humans
Slow Molecules Produced by Photodissociation
A simple method to control molecular translation with a chemical reaction is
demonstrated. Slow NO molecules have been produced by partially canceling the
molecular beam velocity of NO with the recoil velocity of the NO
photofragment. The NO molecules were photodissociated using a UV laser
pulse polarized parallel to the molecular beam. The spatial profiles of NO
molecules showed two peaks corresponding to decelerated and accelerated
molecules, in agreement with theoretical prediction. A significant portion of
the decelerated NO molecules stayed around the initial dissociation positions
even several hundred nanoseconds after their production.Comment: 17 pages, 4 figure
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