RESUMO
We measured the nuclear-recoil ionization yield in silicon with a cryogenic phonon-sensitive gram-scale detector. Neutrons from a monoenergetic beam scatter off of the silicon nuclei at angles corresponding to energy depositions from 4 keV down to 100 eV, the lowest energy probed so far. The results show no sign of an ionization production threshold above 100 eV. These results call for further investigation of the ionization yield theory and a comprehensive determination of the detector response function at energies below the keV scale.
RESUMO
We present limits on spin-independent dark matter-nucleon interactions using a 10.6 g Si athermal phonon detector with a baseline energy resolution of σ_{E}=3.86±0.04(stat)_{-0.00}^{+0.19}(syst) eV. This exclusion analysis sets the most stringent dark matter-nucleon scattering cross-section limits achieved by a cryogenic detector for dark matter particle masses from 93 to 140 MeV/c^{2}, with a raw exposure of 9.9 g d acquired at an above-ground facility. This work illustrates the scientific potential of detectors with athermal phonon sensors with eV-scale energy resolution for future dark matter searches.
RESUMO
The Cryogenic Dark Matter Search low ionization threshold experiment (CDMSlite) achieved efficient detection of very small recoil energies in its germanium target, resulting in sensitivity to lightly ionizing particles (LIPs) in a previously unexplored region of charge, mass, and velocity parameter space. We report first direct-detection limits calculated using the optimum interval method on the vertical intensity of cosmogenically produced LIPs with an electric charge smaller than e/(3×10^{5}), as well as the strongest limits for charge ≤e/160, with a minimum vertical intensity of 1.36×10^{-7} cm^{-2} s^{-1} sr^{-1} at charge e/160. These results apply over a wide range of LIP masses (5 MeV/c^{2} to 100 TeV/c^{2}) and cover a wide range of ßγ values (0.1-10^{6}), thus excluding nonrelativistic LIPs with ßγ as small as 0.1 for the first time.
RESUMO
This corrects the article DOI: 10.1103/PhysRevLett.121.051301.
RESUMO
We present the first limits on inelastic electron-scattering dark matter and dark photon absorption using a prototype SuperCDMS detector having a charge resolution of 0.1 electron-hole pairs (CDMS HVeV, a 0.93 g CDMS high-voltage device). These electron-recoil limits significantly improve experimental constraints on dark matter particles with masses as low as 1 MeV/c^{2}. We demonstrate a sensitivity to dark photons competitive with other leading approaches but using substantially less exposure (0.49 g d). These results demonstrate the scientific potential of phonon-mediated semiconductor detectors that are sensitive to single electronic excitations.
RESUMO
We report the result of a blinded search for weakly interacting massive particles (WIMPs) using the majority of the SuperCDMS Soudan data set. With an exposure of 1690 kg d, a single candidate event is observed, consistent with expected backgrounds. This analysis (combined with previous Ge results) sets an upper limit on the spin-independent WIMP-nucleon cross section of 1.4×10^{-44} (1.0×10^{-44}) cm^{2} at 46 GeV/c^{2}. These results set the strongest limits for WIMP-germanium-nucleus interactions for masses >12 GeV/c^{2}.
RESUMO
We report results of a search for weakly interacting massive particles (WIMPS) with the silicon detectors of the CDMS II experiment. This blind analysis of 140.2 kg day of data taken between July 2007 and September 2008 revealed three WIMP-candidate events with a surface-event background estimate of 0.41(-0.08)(+0.20)(stat)(-0.24)(+0.28)(syst). Other known backgrounds from neutrons and 206Pb are limited to <0.13 and <0.08 events at the 90% confidence level, respectively. The exposure of this analysis is equivalent to 23.4 kg day for a recoil energy range of 7-100 keV for a WIMP of mass 10 GeV/c2. The probability that the known backgrounds would produce three or more events in the signal region is 5.4%. A profile likelihood ratio test of the three events that includes the measured recoil energies gives a 0.19% probability for the known-background-only hypothesis when tested against the alternative WIMP+background hypothesis. The highest likelihood occurs for a WIMP mass of 8.6 GeV/c2 and WIMP-nucleon cross section of 1.9×10(-41) cm2.
RESUMO
Nanoinformatics has recently emerged to address the need of computing applications at the nano level. In this regard, the authors have participated in various initiatives to identify its concepts, foundations and challenges. While nanomaterials open up the possibility for developing new devices in many industrial and scientific areas, they also offer breakthrough perspectives for the prevention, diagnosis and treatment of diseases. In this paper, we analyze the different aspects of nanoinformatics and suggest five research topics to help catalyze new research and development in the area, particularly focused on nanomedicine. We also encompass the use of informatics to further the biological and clinical applications of basic research in nanoscience and nanotechnology, and the related concept of an extended "nanotype" to coalesce information related to nanoparticles. We suggest how nanoinformatics could accelerate developments in nanomedicine, similarly to what happened with the Human Genome and other -omics projects, on issues like exchanging modeling and simulation methods and tools, linking toxicity information to clinical and personal databases or developing new approaches for scientific ontologies, among many others.
RESUMO
We report results from a reanalysis of data from the Cryogenic Dark Matter Search (CDMS II) experiment at the Soudan Underground Laboratory. Data taken between October 2006 and September 2008 using eight germanium detectors are reanalyzed with a lowered, 2 keV recoil-energy threshold, to give increased sensitivity to interactions from weakly interacting massive particles (WIMPs) with masses below â¼10 GeV/c(2). This analysis provides stronger constraints than previous CDMS II results for WIMP masses below 9 GeV/c(2) and excludes parameter space associated with possible low-mass WIMP signals from the DAMA/LIBRA and CoGeNT experiments.
RESUMO
We report on the first axion search results from the Cryogenic Dark Matter Search (CDMS) experiment at the Soudan Underground Laboratory. An energy threshold of 2 keV for electron-recoil events allows a search for possible solar axion conversion into photons or local galactic axion conversion into electrons in the germanium crystal detectors. The solar axion search sets an upper limit on the Primakov coupling g(agammagamma) of 2.4x10(-9) GeV-1 at the 95% confidence level for an axion mass less than 0.1 keV/c2. This limit benefits from the first precise measurement of the absolute crystal plane orientations in this type of experiment. The galactic axion search analysis sets a world-leading experimental upper limit on the axioelectric coupling g(aee) of 1.4x10(-12) at the 90% confidence level for an axion mass of 2.5 keV/c2.
RESUMO
BACKGROUND: Allopathic practitioners in India are outnumbered by practitioners of traditional Indian medicine and homeopathy (TIMH), which is used by up to two-thirds of its population to help meet primary health care needs, particularly in rural areas. India has an estimated 2.5 million HIV infected persons. However, little is known about TIMH use, safety or efficacy in HIV/AIDS management in India, which has one of the largest indigenous medical systems in the world. The purpose of this review was to assess the quality of peer-reviewed, published literature on TIMH for HIV/AIDS care and treatment. RESULTS: Of 206 original articles reviewed, 21 laboratory studies, 17 clinical studies, and 6 previous reviews of the literature were identified that covered at least one system of TIMH, which includes Ayurveda, Unani medicine, Siddha medicine, homeopathy, yoga and naturopathy. Most studies examined either Ayurvedic or homeopathic treatments. Only 4 of these studies were randomized controlled trials, and only 10 were published in MEDLINE-indexed journals. Overall, the studies reported positive effects and even "cure" and reversal of HIV infection, but frequent methodological flaws call into question their internal and external validity. Common reasons for poor quality included small sample sizes, high drop-out rates, design flaws such as selection of inappropriate or weak outcome measures, flaws in statistical analysis, and reporting flaws such as lack of details on products and their standardization, poor or no description of randomization, and incomplete reporting of study results. CONCLUSION: This review exposes a broad gap between the widespread use of TIMH therapies for HIV/AIDS, and the dearth of high-quality data supporting their effectiveness and safety. In light of the suboptimal effectiveness of vaccines, barrier methods and behavior change strategies for prevention of HIV infection and the cost and side effects of antiretroviral therapy (ART) for its treatment, it is both important and urgent to develop and implement a rigorous research agenda to investigate the potential risks and benefits of TIMH and to identify its role in the management of HIV/AIDS and associated illnesses in India.
RESUMO
Following a cortical injury, neurons in areas near and connected to the site of injury begin to degenerate. The observed neuronal death may contribute to the severity of the observed behavioral impairments. The purpose of the present study was to examine if progesterone, a hormone known for its effectiveness at reducing cerebral edema, could protect against secondary neuronal death and facilitate the acquisition of an avoidance learning task in an ablation model of cortical injury. Rats served as sham controls or received bilateral ablation of the medial prefrontal cortex followed by a 10-day regimen of progesterone (4 mg/kg) or oil vehicle (1 ml/kg) beginning 1 h after cortical lesions. Progesterone-treated lesion rats showed a significant facilitation of avoidance learning compared to oil-treated lesion controls. In addition, progesterone-treated lesion animals did not differ from either progesterone- or oil-treated sham controls in avoidance learning. Anatomical analysis revealed that progesterone treatment decreased the amount of neuronal death seen in the striatum and the mediodorsal nucleus of the thalamus. The findings are consistent with the notion that progesterone is an effective neuroprotective agent and suggest that the hormone can reduce the behavioral impairments associated with frontal cortical ablation injury.
Assuntos
Aprendizagem da Esquiva/efeitos dos fármacos , Morte Celular/efeitos dos fármacos , Neurônios/efeitos dos fármacos , Córtex Pré-Frontal/fisiologia , Progesterona/farmacologia , Animais , Contagem de Células , Masculino , Neostriado/anatomia & histologia , Neostriado/fisiologia , Córtex Pré-Frontal/anatomia & histologia , Ratos , Tálamo/anatomia & histologia , Tálamo/fisiologiaRESUMO
Rats were trained on a four-way shuttle box with a compound light-tone conditioned stimulus (CS) until they emitted 7 avoidance responses in 10 trials (7/10) prior to bilateral ablation of the visual cortex or sham surgery. On Day 5 after surgery, rats were cued with either the compound light-tone CS, the light or tone portion of the CS only, or had no exposure to the CS. On Day 10 after surgery, all animals were tested for avoidance retention under the same conditions as preoperative training. The findings indicate that following a lesion, cueing with the light-tone compound CS facilitates performance as does light alone. Cueing to the tone alone has no effect. In sham animals, only cueing with the light-tone CS was effective in enhancing avoidance retention. Results are interpreted as early and modality-specific sensory cueing may facilitate the recovery process.
Assuntos
Aprendizagem da Esquiva/fisiologia , Sinais (Psicologia) , Córtex Visual/fisiologia , Estimulação Acústica , Animais , Masculino , Estimulação Luminosa , Ratos , Ratos Sprague-Dawley , Córtex Visual/anatomia & histologiaRESUMO
The rat medial prefrontal cortex (PFC) is believed to play a central role in working memory and selective attention processes. More recently, it has been shown that the effects of large PFC lesions on working memory may be due to the prelimbic area of the PFC. The aim of the present study was to compare the effects of lesions of the prelimbic area with PFC lesions that involved or spared the prelimbic area on shuttlebox avoidance and radial maze learning in rats. The findings indicate that rats with PFC lesions that spared the prelimbic area were impaired at avoidance but not radial arm maze learning, whereas rats with prelimbic lesions or PFC lesions that included this area were impaired on the radial arm maze but not the avoidance learning task. Results support the notion that the medial frontal cortex of the rat is a functionally dissociable region and suggest that the prelimbic area appears to be critical for working memory, but less so for attention processes.
Assuntos
Comportamento Animal/fisiologia , Sistema Límbico/fisiologia , Córtex Pré-Frontal/fisiologia , Animais , Aprendizagem da Esquiva/fisiologia , Contagem de Células , Feminino , Sistema Límbico/anatomia & histologia , Aprendizagem em Labirinto/fisiologia , Atividade Motora/fisiologia , Degeneração Neural/fisiopatologia , Córtex Pré-Frontal/anatomia & histologia , Córtex Pré-Frontal/química , Ratos , Ratos Sprague-Dawley , Tálamo/fisiologiaRESUMO
Amphetamine produces locomotor stereotypy (repetitive routes of locomotion) in an open field. In this research we tested the ability of the D1 antagonist SKF 83566 and the D2 antagonist sulpiride to block the locomotor stereotypy produced by 2 mg/kg amphetamine. SKF 83566 decreased amphetamine-induced locomotor stereotypy; sulpiride had no consistent effect on amphetamine-induced locomotor stereotypy. There was no evidence that either antagonist potentiated the effect of the other.
Assuntos
Anfetamina/antagonistas & inibidores , Anfetamina/toxicidade , Antagonistas de Dopamina/uso terapêutico , Antagonistas dos Receptores de Dopamina D2 , Inibidores da Captação de Dopamina/antagonistas & inibidores , Inibidores da Captação de Dopamina/toxicidade , Receptores de Dopamina D1/antagonistas & inibidores , Comportamento Estereotipado/efeitos dos fármacos , 2,3,4,5-Tetra-Hidro-7,8-Di-Hidroxi-1-Fenil-1H-3-Benzazepina/análogos & derivados , 2,3,4,5-Tetra-Hidro-7,8-Di-Hidroxi-1-Fenil-1H-3-Benzazepina/uso terapêutico , Animais , Interações Medicamentosas , Masculino , Ratos , Ratos Wistar , Sulpirida/uso terapêuticoRESUMO
Like amphetamine, scopolamine produces locomotor stereotypy (repetitive routes of locomotion) in an open field. To determine whether locomotor stereotypy is a common behavioral effect of anticholingeric agents, several doses of the anticholinergic dexbenzetimide were tested for the ability to produce locomotor stereotypy; like scopolamine, dexbenzetimide produced locomotor stereotypy. To investigate a possible role of dopamine in anticholinergic-induced locomotor stereotypy, we tested the ability of the dopamine D1 antagonist SKF 83566 and the D2 antagonist sulpiride to block the locomotor stereotypy induced by scopolamine as well as dexbenzetimide. SKF 83566 blocked scopolamine- and dexbenzetimide-induced locomotor stereotypy; sulpiride did not reduce dexbenzetimide-induced locomotor stereotypy, but enhanced scopolamine-induced locomotor stereotypy. Hyperlocomotion was reduced by both dopamine antagonists. Results are interpreted in support of the notion that dopamine is the likely candidate mediating locomotor stereotypy.
Assuntos
2,3,4,5-Tetra-Hidro-7,8-Di-Hidroxi-1-Fenil-1H-3-Benzazepina/análogos & derivados , Dexetimida/antagonistas & inibidores , Antagonistas de Dopamina/farmacologia , Locomoção/efeitos dos fármacos , Antagonistas Muscarínicos/farmacologia , Escopolamina/antagonistas & inibidores , Comportamento Estereotipado/efeitos dos fármacos , Sulpirida/farmacologia , 2,3,4,5-Tetra-Hidro-7,8-Di-Hidroxi-1-Fenil-1H-3-Benzazepina/farmacologia , Animais , Dexetimida/farmacologia , Antagonistas dos Receptores de Dopamina D2 , Interações Medicamentosas , Masculino , Ratos , Ratos Wistar , Receptores de Dopamina D1/antagonistas & inibidores , Escopolamina/farmacologiaAssuntos
Terapias Complementares , Neoplasias/terapia , Ensaios Clínicos Fase III como Assunto , Terapias Complementares/legislação & jurisprudência , Terapias Complementares/normas , Terapias Complementares/tendências , Humanos , Neoplasias Pulmonares/terapia , Masculino , National Institutes of Health (U.S.) , Neoplasias da Próstata/terapia , Ensaios Clínicos Controlados Aleatórios como Assunto , Estados UnidosRESUMO
Astrophysical observations indicate that dark matter constitutes most of the mass in our universe, but its nature remains unknown. Over the past decade, the Cryogenic Dark Matter Search (CDMS II) experiment has provided world-leading sensitivity for the direct detection of weakly interacting massive particle (WIMP) dark matter. The final exposure of our low-temperature germanium particle detectors at the Soudan Underground Laboratory yielded two candidate events, with an expected background of 0.9 +/- 0.2 events. This is not statistically significant evidence for a WIMP signal. The combined CDMS II data place the strongest constraints on the WIMP-nucleon spin-independent scattering cross section for a wide range of WIMP masses and exclude new parameter space in inelastic dark matter models.