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1.
Phys Rev Lett ; 126(9): 091101, 2021 Mar 05.
Article in English | MEDLINE | ID: mdl-33750144

ABSTRACT

We perform a comprehensive study of Milky Way (MW) satellite galaxies to constrain the fundamental properties of dark matter (DM). This analysis fully incorporates inhomogeneities in the spatial distribution and detectability of MW satellites and marginalizes over uncertainties in the mapping between galaxies and DM halos, the properties of the MW system, and the disruption of subhalos by the MW disk. Our results are consistent with the cold, collisionless DM paradigm and yield the strongest cosmological constraints to date on particle models of warm, interacting, and fuzzy dark matter. At 95% confidence, we report limits on (i) the mass of thermal relic warm DM, m_{WDM}>6.5 keV (free-streaming length, λ_{fs}≲10h^{-1} kpc), (ii) the velocity-independent DM-proton scattering cross section, σ_{0}<8.8×10^{-29} cm^{2} for a 100 MeV DM particle mass [DM-proton coupling, c_{p}≲(0.3 GeV)^{-2}], and (iii) the mass of fuzzy DM, m_{ϕ}>2.9×10^{-21} eV (de Broglie wavelength, λ_{dB}≲0.5 kpc). These constraints are complementary to other observational and laboratory constraints on DM properties.

2.
Phys Rev Lett ; 124(10): 101102, 2020 Mar 13.
Article in English | MEDLINE | ID: mdl-32216401

ABSTRACT

In recent years, many γ-ray sources have been identified, yet the unresolved component hosts valuable information on the faintest emission. In order to extract it, a cross-correlation with gravitational tracers of matter in the Universe has been shown to be a promising tool. We report here the first identification of a cross-correlation signal between γ rays and the distribution of mass in the Universe probed by weak gravitational lensing. We use data from the Dark Energy Survey Y1 weak lensing data and the Fermi Large Area Telescope 9-yr γ-ray data, obtaining a signal-to-noise ratio of 5.3. The signal is mostly localized at small angular scales and high γ-ray energies, with a hint of correlation at extended separation. Blazar emission is likely the origin of the small-scale effect. We investigate implications of the large-scale component in terms of astrophysical sources and particle dark matter emission.

3.
Phys Rev Lett ; 122(17): 171301, 2019 May 03.
Article in English | MEDLINE | ID: mdl-31107093

ABSTRACT

The combination of multiple observational probes has long been advocated as a powerful technique to constrain cosmological parameters, in particular dark energy. The Dark Energy Survey has measured 207 spectroscopically confirmed type Ia supernova light curves, the baryon acoustic oscillation feature, weak gravitational lensing, and galaxy clustering. Here we present combined results from these probes, deriving constraints on the equation of state, w, of dark energy and its energy density in the Universe. Independently of other experiments, such as those that measure the cosmic microwave background, the probes from this single photometric survey rule out a Universe with no dark energy, finding w=-0.80_{-0.11}^{+0.09}. The geometry is shown to be consistent with a spatially flat Universe, and we obtain a constraint on the baryon density of Ω_{b}=0.069_{-0.012}^{+0.009} that is independent of early Universe measurements. These results demonstrate the potential power of large multiprobe photometric surveys and pave the way for order of magnitude advances in our constraints on properties of dark energy and cosmology over the next decade.

4.
Phys Rev Lett ; 115(5): 051301, 2015 Jul 31.
Article in English | MEDLINE | ID: mdl-26274409

ABSTRACT

We present a mass map reconstructed from weak gravitational lensing shear measurements over 139 deg2 from the Dark Energy Survey science verification data. The mass map probes both luminous and dark matter, thus providing a tool for studying cosmology. We find good agreement between the mass map and the distribution of massive galaxy clusters identified using a red-sequence cluster finder. Potential candidates for superclusters and voids are identified using these maps. We measure the cross-correlation between the mass map and a magnitude-limited foreground galaxy sample and find a detection at the 6.8σ level with 20 arc min smoothing. These measurements are consistent with simulated galaxy catalogs based on N-body simulations from a cold dark matter model with a cosmological constant. This suggests low systematics uncertainties in the map. We summarize our key findings in this Letter; the detailed methodology and tests for systematics are presented in a companion paper.

5.
Astrophys J ; 531(1): L61-L65, 2000 Mar 01.
Article in English | MEDLINE | ID: mdl-10673415

ABSTRACT

We report the discovery of a second field methane brown dwarf from the commissioning data of the Sloan Digital Sky Survey (SDSS). The object, SDSS J134646.45-003150.4 (hereafter SDSS 1346-00), was selected because of its very red color and stellar appearance. Its spectrum between 0.8 and 2.5 µm is dominated by strong absorption bands of H2O and CH4 and closely mimics those of Gliese 229B and SDSS 162414.37+002915.6 (hereafter SDSS 1624+00), two other known methane brown dwarfs. SDSS 1346-00 is approximately 1.5 mag fainter than Gliese 229B, suggesting that it lies about 11 pc from the Sun. The ratio of flux at 2.1 µm to that at 1.27 µm is larger for SDSS 1346-00 than for Gliese 229B and SDSS 1624+00, which suggests that SDSS 1346-00 has a slightly higher effective temperature than the others. Based on a search area of 130 deg2 and a detection limit of z*=19.8, we estimate a space density of 0.05 pc-3 for methane brown dwarfs with Teff approximately 1000 K in the 40 pc3 volume of our search. This estimate is based on small-sample statistics and should be treated with appropriate caution.

6.
Astrophys J ; 526(2): L57-L60, 1999 Dec 01.
Article in English | MEDLINE | ID: mdl-10550277

ABSTRACT

We report observations of a luminous unresolved object at redshift z=4.62, with a featureless optical spectrum redward of the Lyalpha forest region, discovered from Sloan Digital Sky Survey commissioning data. The redshift is determined by the onset of the Lyalpha forest at lambda approximately 6800 Å and a Lyman limit system at lambda=5120 Å. A strong Lyalpha absorption system with weak metal absorption lines at z=4.58 is also identified in the spectrum. The object has a continuum absolute magnitude of -26.6 at 1450 Å in the rest frame (h0=0.5, q0=0.5) and therefore cannot be an ordinary galaxy. It shows no radio emission (the 3 sigma upper limit of its flux at 6 cm is 60 µJy), indicating a radio-to-optical flux ratio at least as small as that of the radio-weakest BL Lacertae objects known. It is also not linearly polarized to a 3 sigma upper limit of 4% in the observed I band. Therefore, it is either the most distant BL Lac object known to date, with very weak radio emission, or a new type of unbeamed quasar, whose broad emission line region is very weak or absent.

7.
Anesth Analg ; 79(3): 607-8, 1994 Sep.
Article in English | MEDLINE | ID: mdl-8067581
8.
J Laryngol Otol ; 106(10): 905-7, 1992 Oct.
Article in English | MEDLINE | ID: mdl-1474315

ABSTRACT

A case of an unilateral sensorineural hearing loss of sudden onset, due to an osteoma in the internal auditory canal is presented. As far as the authors are aware an osteoma at this site associated with a hearing loss occurring within a few hours has not previously been reported.


Subject(s)
Ear Neoplasms/complications , Ear, Inner , Hearing Loss, Sensorineural/etiology , Osteoma/complications , Adult , Ear Neoplasms/diagnostic imaging , Ear, Inner/diagnostic imaging , Humans , Male , Osteoma/diagnostic imaging , Tomography, X-Ray Computed
9.
Clin Otolaryngol Allied Sci ; 17(1): 60-6, 1992 Feb.
Article in English | MEDLINE | ID: mdl-1555322

ABSTRACT

Recent research on inflammatory sinus disease has implicated a central role for the ethmoid labyrinth, which may influence changes in the maxillary and frontal sinuses. CT can provide excellent definition of the paranasal sinuses and particularly the ethmoids, which is a prerequisite for endoscopic surgery. We describe a prospective series of 110 coronal CT scans performed on patients with a clinical diagnosis of sinusitis who had undergone diagnostic nasal endoscopies and medical treatment prior to surgery. 86% of the scans showed abnormal mucosal thickening. The ethmoids were affected in 73% and the maxillary sinus in 64%. Pneumatization of the middle turbinate was a common variant and when present was associated with anterior ethmoid disease in 60% of patients. Anterior ethmoid inflammatory changes were demonstrable in 95% of patients with maxillary sinus disease. Direct coronal CT can readily demonstrate disease in the infundibulum, frontal recess and posterior ethmoids in the same orientation confronting the endoscopist, and helps in the planning of ethmoidal surgery. Following surgery the sinuses can be directly inspected in outpatients which reduces the need for any further plain radiographs. It is important that the diagnosis of sinusitis is not based on CT findings alone as isolated areas of mucosal thickening are common in the normal population.


Subject(s)
Endoscopy , Sinusitis/diagnostic imaging , Sinusitis/surgery , Tomography, X-Ray Computed , Ethmoid Sinusitis/diagnostic imaging , Ethmoid Sinusitis/surgery , Humans , Maxillary Sinusitis/diagnostic imaging , Maxillary Sinusitis/surgery , Preoperative Care , Prospective Studies
10.
Exp Aging Res ; 17(3): 157-76, 1991.
Article in English | MEDLINE | ID: mdl-1810743

ABSTRACT

Faced with an aging labor force, industrial planners are worried about the possible need to redesign jobs and workspaces in the future. One area of concern is the changes that occur in body size characteristics as people age. Although no true database for the anthropometry of the American worker exists, available surveys and studies that include older individuals (40 to 70 years), and errors associated with these studies, are discussed. Using sample mean values from selected cross-sectional and longitudinal studies, the changes in weight and selected body dimensions are traced from the third to the eighth decade of life. As a practical exercise, age-associated changes in a number of workspace dimensions are tested against recommended design values for seated work stations. While acknowledging the need for flexibility in future workplace designs the authors conclude that age-related changes in body size are insufficient in themselves to justify the resizing of existing ergonomically-designed workplaces.


Subject(s)
Aging/physiology , Anthropometry , Ergonomics , Occupational Medicine , Aged , Body Constitution , Humans , Middle Aged
11.
Br J Radiol ; 63(751): 512-6, 1990 Jul.
Article in English | MEDLINE | ID: mdl-2390686

ABSTRACT

Insertion of a sound amplification device into the round window niche (extracochlear implant) or into the coils of the cochlea (intracochlear implant) can give significant benefits to some carefully selected, severely deaf patients. Imaging has an essential role in selective and pre-operative assessment. Severe otosclerosis and post-meningitic labyrinthitis ossificans are common causes of deafness in these patients and can be demonstrated by computed tomography (CT). The most suitable side for operation can be assessed. We describe our experiences with 165 patients, 69 of whom were found suitable for implants. Thin (1 mm) section CT in axial and coronal planes is the best imaging investigation of the petrous temporal bones but the place of magnetic resonance scanning to confirm that the inner ear is fluid-filled and polytomography to show a multichannel implant in the cochlea is discussed. No implants were used for congenital deformities, but some observations are made of this type of structural deformity of the inner ear.


Subject(s)
Cochlea/diagnostic imaging , Cochlear Implants , Preoperative Care/methods , Cochlear Diseases/complications , Cochlear Diseases/diagnostic imaging , Deafness/etiology , Deafness/therapy , Humans , Labyrinth Diseases/complications , Labyrinth Diseases/diagnostic imaging , Tomography, X-Ray Computed
15.
Br J Radiol ; 60(719): 1059-61, 1987 Nov.
Article in English | MEDLINE | ID: mdl-3690149

ABSTRACT

This study reviews the radiographs and clinical case notes of 897 patients who attended the Accident and Emergency (A & E) Department of Leicester Royal Infirmary, over an 8-month period, for whom radiographs of the cervical spine were requested. The radiological interpretations by the casualty officers and junior radiologists in training were compared with those by a consultant radiologist and large discrepancies were observed. There was a predominance of fractures and subluxations at the levels of C1 and C2, and at C7 and T1. A study of the adequacy of the radiographs has shown that 90% of the lateral radiographs included C7 but only 57% included T1. Through-the-mouth views were adequate for interpretation in 67% of cases. The practice of the A & E and radiology departments at the Leicester Royal Infirmary is briefly described. The poor performance of the casualty officers and junior radiologists is discussed and suggestions made which might improve the accuracy of the radiological diagnosis of cervical-spine injuries in the A & E department.


Subject(s)
Cervical Vertebrae/diagnostic imaging , Emergency Service, Hospital/standards , Fractures, Bone/diagnostic imaging , Joint Dislocations/diagnostic imaging , Adolescent , Adult , Aged , Aged, 80 and over , Cervical Vertebrae/injuries , Child , Child, Preschool , Diagnostic Errors , England , Humans , Infant , Middle Aged , Radiography , Radiology Department, Hospital/standards
16.
Article in English | MEDLINE | ID: mdl-6863096

ABSTRACT

Regional and total body heat loss rates of human subjects at rest were measured simultaneously by means of an array of heat flux transducers and with a tube suit calorimeter. Conditions ranged from thermal comfort to strong cooling. A high degree of correlation was found between heat loss rates determined by the two independent techniques. For the head and arms, the transducer array system measured less heat loss than the suit. For the torso and legs, measurements by the two methods were equivalent. For the whole body, the transducer system yielded a heat loss rate 87% of the suit calorimeter value.


Subject(s)
Body Temperature Regulation , Calorimetry/instrumentation , Adult , Clothing , Humans , Male , Transducers
17.
Hum Nutr Clin Nutr ; 37(2): 117-31, 1983 Mar.
Article in English | MEDLINE | ID: mdl-6575005

ABSTRACT

In groups of four, men and women in their 40s and 50s, some of them lean and some overweight, overate for 30 d by 1000 kcal/d (4186 kJ/d) more than they needed to maintain weight. On an average dietary mixture for Americans they gained a mean of 2.68 kg, and on a diet high in carbohydrate (60 per cent of energy) they gained 2.73 kg. However, on a diet high in protein and fat (70 per cent of energy), they gained significantly less, 1.75 kg. On all three diets the subjects should have gained 5 kg, if adipose tissue has an energy density of 6 kcal/g, and had there been no adaptation. There was adaptation, as evidenced by an average 7 per cent increase in thermogenesis, which was measured by 24-h direct and indirect calorimetry. Energy balances were calculated from: bomb calorimeter values for food and body waste; change in fuel stores from body composition measured by densitometry; and daily expenditure estimated from the net food intake needed to maintain body weight during a 30-d control period. During overeating, energy intake matched energy losses (including fuel storage) for the average diet and the high-carbohydrate diet, but on the diet high in protein and fat energy intake exceeded losses by more than 500 kcal/d (2093 kJ/d). Thus smaller than expected weight gains from overeating (luxuskonsumption) were largely explained by increased thermogenesis, except when the diet was high in protein and fat. Lean and overweight subjects did not differ in weight gain, loss of energy in urine and faeces, or thermogenesis from overeating.


Subject(s)
Diet , Feeding and Eating Disorders/metabolism , Hyperphagia/metabolism , Obesity/metabolism , Thinness/metabolism , Adaptation, Physiological , Adult , Body Constitution , Calorimetry , Dietary Carbohydrates/administration & dosage , Dietary Fats/administration & dosage , Dietary Proteins/administration & dosage , Energy Intake , Energy Metabolism , Female , Humans , Male , Middle Aged
18.
Aviat Space Environ Med ; 54(3): 191-201, 1983 Mar.
Article in English | MEDLINE | ID: mdl-6342596

ABSTRACT

A Reverse Gradient Garment (RGG) was used to intermittently induce venous pooling in the extremities of a magnitude similar to that seen in going from a lying to standing position during the course of a 15-d period of horizontal bed rest. Venous pooling failed to improve bed-rest-induced losses in +2.5 Gz and +3.0 Gz centrifugation tolerance or to prevent increased heart-rate responses to lower-body negative pressure (LBNP). Four subjects served as controls, four were treated. Tests during the 7-d recovery period showed fluid/electrolyte and body composition values to have returned to pre-bed-rest levels with continued depression of acceleration tolerance times (56% decreased at +2.5 Gz and 74% decreased at +3.0 Gz compared to pre-bed-rest levels) and exaggerated blood insulin response on glucose tolerance testing (blood insulin for treated group increased 95% at 1 h before bed rest and 465% during recovery). This study demonstrates that the physiologic changes after bed rest persist for significant periods of time. Acceleration tolerance time proved to be a sensitive test for the deconditioning process.


Subject(s)
Bed Rest/adverse effects , Blood Circulation , Gravity Suits , Acceleration , Adult , Aerospace Medicine , Body Composition , Glucose Tolerance Test , Humans , Insulin/blood , Lower Body Negative Pressure , Male , Physical Exertion , Time Factors , Urine/analysis
19.
Article in English | MEDLINE | ID: mdl-7096156

ABSTRACT

The purpose of this study was to deliberately induce venous pooling the lower extremities of bed-rested subjects to determine whether such distention may reverse the reduction in maximal O2 uptake that has regularly been observed. Bed-rest deconditioning was assessed in eight healthy male subjects by measuring submaximal and maximal O2 uptake (VO2 max), ventilation, and heart rate (HRmax) before and after 15 days of bed rest. During bed rest four subjects in the experimental group received daily treatments of venous pooling for 210 min/day with a reverse gradient garment (RGG), whereas the four subjects in the control group received no treatment. Compared with prebed-rest values, VO2max was reduced by 14.0 (P less than 0.05), HRmax was increased by 4.2 (P less than 0.05), and endurance time for the exercise test was decreased by 9.2% (P less than 0.05) in the control group. In the RGG group, VO2max, HRmax, and endurance time were essentially unchanged after bed rest. The plasma volume (PV) of the control group decreased by 16.7 (P less than 0.05) after bed rest compared with a 10.3% (not significant) reduction in the RGG group. The percent delta PV was related to the percent delta VO2 max (r = 0.75, P less than 0.05) and percent delta HR max (r = 0.65, P less than 0.05). The data support the hypothesis that the lack of venous pooling and associated fluid shifts contribute the decrement in VO2 max associated with bed-rest deconditioning.


Subject(s)
Bed Rest , Heart Rate , Oxygen Consumption , Physical Exertion , Veins/physiology , Adult , Erythrocyte Volume , Extremities/blood supply , Hematocrit , Humans , Male , Plasma Volume , Regional Blood Flow , Respiration
20.
Am J Clin Nutr ; 33(6): 1287-98, 1980 Jun.
Article in English | MEDLINE | ID: mdl-7386416

ABSTRACT

In six 24-hr measurements of energy balance, direct and indirect calorimetry agreed within +/-3%, which is probably the range of experimental error. But in seven other 24-hr periods there was disagreement in the range of 8 to 23%, and these were usually days when the subjects ate much less than they spent metabolically. Our direct calorimeter is an insulated, water cooled suit. Continous measurements of O2 consumption and CO2 production provided data on metabolic expenditure (M) by indirect calorimetry. The 24-hr values for M matched the energy losses within +/-60 kcal (+/-3% of M) in four men who rested all day and lay down to sleep at night. Similar agreement was seen in one of the four who worked on a treadmill for 4 hr and stayed busy all day. but in another energy losses were 342 kcal greater than M (10% of M). When the experiments gave values for M minus the losses greater than +/-60 kcal, this is called "unmeasured energy". In further experiments, two subjects stayed awake for 24 hr, and their unmeasured energies were 279 and 393 kcal. The same two men, eating sparingly, also worked for 24 hr so as to double their resting metabolic expenditures; the unmeasured energies were even larger, 380 and 958 kcal. When they repeated the 24 hr of mild work, but ate nearly as much as they spent metabolically, one man was near energy balance, while the other showed an unmeasured energy of -363 kcal. Little heat storage was evident in these experiments; therefore, heat balance was present and energy balance should have been present. In the group of 13 experiments, it appeared that the greater the food deficit, the larger was the unmeasured energy (excess of metabolic expenditure over loss of energy).


Subject(s)
Calorimetry, Indirect , Calorimetry , Diet , Energy Metabolism , Adult , Body Temperature Regulation , Energy Intake , Feeding Behavior , Humans , Male , Middle Aged , Physical Exertion , Wakefulness
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