264 research outputs found
Dynamic Resonance of Light in Fabry-Perot Cavities
The dynamics of light in Fabry-Perot cavities with varying length and input
laser frequency are analyzed and the exact condition for resonance is derived.
This dynamic resonance depends on the light transit time in the cavity and the
Doppler effect due to the mirror motions. The response of the cavity to length
variations is very different from its response to laser frequency variations.
If the frequency of these variations is equal to multiples of the cavity free
spectral range, the response to length is maximized while the response to the
laser frequency is zero. Implications of these results for the detection of
gravitational waves using kilometer-scale Fabry-Perot cavities are discussed
Observed Effect of Magnetic Fields on the Propagation of Magnetoacoustic Waves in the Lower Solar Atmosphere
We study Hinode/SOT-FG observations of intensity fluctuations in Ca II H-line
and G-band image sequences and their relation to simultaneous and co-spatial
magnetic field measurements. We explore the G-band and H-line intensity
oscillation spectra both separately and comparatively via their relative phase
differences, time delays and cross-coherences. In the non-magnetic situations,
both sets of fluctuations show strong oscillatory power in the 3 - 7 mHz band
centered at 4.5 mHz, but this is suppressed as magnetic field increases. A
relative phase analysis gives a time delay of H-line after G-band of 20\pm1 s
in non-magnetic situations implying a mean effective height difference of 140
km. The maximum coherence is at 4 - 7 mHz. Under strong magnetic influence the
measured delay time shrinks to 11 s with the peak coherence near 4 mHz. A
second coherence maximum appears between 7.5 - 10 mHz. Investigation of the
locations of this doubled-frequency coherence locates it in diffuse rings
outside photospheric magnetic structures. Some possible interpretations of
these results are offered.Comment: 19 pages, 6 figure
The gravitationally lensed, luminous infrared galaxy IRAS F10214+4724 observed with XMM-Newton
We report on a short XMM-Newton observation of the gravitationally-lensed,
luminous infrared galaxy IRAS F10214+4724 at z=2.3. A faint X-ray source is
detected at 4 sigma. The observed 0.5-2 keV (1.7-6.6 keV in the rest-frame)
flux is 1.3e-15 erg/s/cm2 and the spectral slope in the rest-frame 1-10 keV
band is Gamma~2. These results agree with those obtained from the Chandra X-ray
Observatory, given the large uncertainties in both measurements. While possible
evidence for excess emission above 5 keV is seen, we suspect this excess might
be either spurious or not related to the infrared galaxy.Comment: 4 pages, 2 figures, New Astronomy in pres
A Geometry of the Generations
We propose a geometric theory of flavor based on the discrete group
, in the context of the minimal supersymmetric standard model. The
group treats three objects symmetrically, while making fundamental distinctions
between the generations. The top quark is the only heavy quark in the symmetry
limit, and the first and second generation squarks are degenerate. The
hierarchical nature of Yukawa matrices is a consequence of a sequential
breaking of .Comment: 10 pages, 1 EPS figure as uuencoded tar-compressed file, uses
psfig.st
Flavor at the TeV Scale with Extra Dimensions
Theories where the Standard Model fields reside on a 3-brane, with a low
fundamental cut-off and extra dimensions, provide alternative solutions to the
gauge hierarchy problem. However, generating flavor at the TeV scale while
avoiding flavor-changing difficulties appears prohibitively difficult at first
sight. We argue to the contrary that this picture allows us to lower flavor
physics close to the TeV scale. Small Yukawa couplings are generated by
``shining'' badly broken flavor symmetries from distant branes, and flavor and
CP-violating processes are adequately suppressed by these symmetries. We
further show how the extra dimensions avoid four dimensional disasters
associated with light fields charged under flavor. We construct elegant and
realistic theories of flavor based on the maximal U(3)^5 flavor symmetry which
naturally generate the simultaneous hierarchy of masses and mixing angles.
Finally, we introduce a new framework for predictive theories of flavor, where
our 3-brane is embedded within highly symmetrical configurations of
higher-dimensional branes.Comment: 40 pages, 8 figure
Multiwavelength studies of MHD waves in the solar chromosphere: An overview of recent results
The chromosphere is a thin layer of the solar atmosphere that bridges the
relatively cool photosphere and the intensely heated transition region and
corona. Compressible and incompressible waves propagating through the
chromosphere can supply significant amounts of energy to the interface region
and corona. In recent years an abundance of high-resolution observations from
state-of-the-art facilities have provided new and exciting ways of
disentangling the characteristics of oscillatory phenomena propagating through
the dynamic chromosphere. Coupled with rapid advancements in
magnetohydrodynamic wave theory, we are now in an ideal position to thoroughly
investigate the role waves play in supplying energy to sustain chromospheric
and coronal heating. Here, we review the recent progress made in
characterising, categorising and interpreting oscillations manifesting in the
solar chromosphere, with an impetus placed on their intrinsic energetics.Comment: 48 pages, 25 figures, accepted into Space Science Review
National Beef Quality Audit-2016: Transportation, mobility, and harvest-floor assessments of targeted characteristics that affect quality and value of cattle, carcasses, and by-products
The National Beef Quality Audit-2016 (NBQA-2016) was conducted to assess current transportation, mobility, and quality characteristics of U.S. fed steers and heifers. Data were collected at 17 beef processing facilities between March and November 2016. About 8,000 live cattle were evaluated for transportation and mobility, and about 25,000 carcasses were evaluated on the slaughter floor. Cattle were in transit to the slaughter facility for a mean duration of 2.7 h from a mean distance of 218.5 km using trailers with dimensions ranging from 17.84 m2 to 59.09 m2. Area allotted per animal averaged 1.13 m2 and ranged from 0.85 m2 to 2.28 m2. A total of 96.8% of cattle received a mobility score of 1 (walks easily, no apparent lameness). Identification types (35.1% had multiple) were lot visual tags (61.5%), individual tags (55.0%), electronic tags (16.9%), metal-clip tags (9.2%), bar-coded tags (0.05%), wattles (0.01%), and other (2.6%). Cattle were black-hided (57.8%), Holstein (20.4%), red-hided (10.5%), yellow-hided (4.8%), gray-hided (2.9%), brown-hided (1.3%), and white-hided (1.1%). Unbranded hides were observed on 74.3% of cattle; 18.6% had brands located on the butt, 6.3% on the side, and 1.3% on the shoulder (values exceed 100% due to multiple brands). For hide-on carcasses, 37.7% displayed no mud or manure; specific locations for mud or manure were legs (40.8%), belly (33.0%), tail region (15.5%), side (6.8%), and top-line (3.9%). Cattle without horns represented 83.3% of the sample, and cattle that did have horns measured: \u3c 2.54 cm (5.5%), 2.54 to 12.7 cm (8.3%), and \u3e 12.7 cm (2.9%). Carcasses without bruises represented 61.1% of those sampled, whereas 28.2% had 1, 8.2% had 2, 2.1% had 3, and 0.3% had 4 bruises. Of those carcasses with a bruise, the bruise was located on the loin (29.7%), round (27.8%), chuck (16.4%), rib (14.4%), and brisket/plate/flank (11.6%). Frequencies of offal condemnations were livers (30.8%), lungs (18.2%), viscera (16.3%), hearts (11.1%), heads (2.7%), and tongues (2.0%). Compared to NBQA-2011, fewer cattle were identified for traceability, fewer were black-hided, a greater number were Holstein cattle, more with no brand and no horns, fewer without bruises, more liver, lung, and viscera condemnations, and fewer heads and tongues were condemned. The NBQA remains an influential survey for the U.S. beef industry to provide benchmarks and strategic plans for continued improvement of beef quality and consistency
Detector Description and Performance for the First Coincidence Observations between LIGO and GEO
For 17 days in August and September 2002, the LIGO and GEO interferometer
gravitational wave detectors were operated in coincidence to produce their
first data for scientific analysis. Although the detectors were still far from
their design sensitivity levels, the data can be used to place better upper
limits on the flux of gravitational waves incident on the earth than previous
direct measurements. This paper describes the instruments and the data in some
detail, as a companion to analysis papers based on the first data.Comment: 41 pages, 9 figures 17 Sept 03: author list amended, minor editorial
change
The management of diabetic ketoacidosis in children
The object of this review is to provide the definitions, frequency, risk factors, pathophysiology, diagnostic considerations, and management recommendations for diabetic ketoacidosis (DKA) in children and adolescents, and to convey current knowledge of the causes of permanent disability or mortality from complications of DKA or its management, particularly the most common complication, cerebral edema (CE). DKA frequency at the time of diagnosis of pediatric diabetes is 10%–70%, varying with the availability of healthcare and the incidence of type 1 diabetes (T1D) in the community. Recurrent DKA rates are also dependent on medical services and socioeconomic circumstances. Management should be in centers with experience and where vital signs, neurologic status, and biochemistry can be monitored with sufficient frequency to prevent complications or, in the case of CE, to intervene rapidly with mannitol or hypertonic saline infusion. Fluid infusion should precede insulin administration (0.1 U/kg/h) by 1–2 hours; an initial bolus of 10–20 mL/kg 0.9% saline is followed by 0.45% saline calculated to supply maintenance and replace 5%–10% dehydration. Potassium (K) must be replaced early and sufficiently. Bicarbonate administration is contraindicated. The prevention of DKA at onset of diabetes requires an informed community and high index of suspicion; prevention of recurrent DKA, which is almost always due to insulin omission, necessitates a committed team effort
Coupling between Primary Terrestrial Succession and the Trophic Development of Lakes at Glacier Bay, Alaska
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