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1.
Nature ; 531(7592): 74-7, 2016 Mar 03.
Artículo en Inglés | MEDLINE | ID: mdl-26878235

RESUMEN

Spontaneous emission of radiation is one of the fundamental mechanisms by which an excited quantum system returns to equilibrium. For spins, however, spontaneous emission is generally negligible compared to other non-radiative relaxation processes because of the weak coupling between the magnetic dipole and the electromagnetic field. In 1946, Purcell realized that the rate of spontaneous emission can be greatly enhanced by placing the quantum system in a resonant cavity. This effect has since been used extensively to control the lifetime of atoms and semiconducting heterostructures coupled to microwave or optical cavities, and is essential for the realization of high-efficiency single-photon sources. Here we report the application of this idea to spins in solids. By coupling donor spins in silicon to a superconducting microwave cavity with a high quality factor and a small mode volume, we reach the regime in which spontaneous emission constitutes the dominant mechanism of spin relaxation. The relaxation rate is increased by three orders of magnitude as the spins are tuned to the cavity resonance, demonstrating that energy relaxation can be controlled on demand. Our results provide a general way to initialize spin systems into their ground state and therefore have applications in magnetic resonance and quantum information processing. They also demonstrate that the coupling between the magnetic dipole of a spin and the electromagnetic field can be enhanced up to the point at which quantum fluctuations have a marked effect on the spin dynamics; as such, they represent an important step towards the coherent magnetic coupling of individual spins to microwave photons.

2.
Genome Announc ; 4(1)2016 Jan 07.
Artículo en Inglés | MEDLINE | ID: mdl-26744368

RESUMEN

Burkholderia mallei, the etiologic agent of glanders, is a Gram-negative, nonmotile, facultative intracellular pathogen. Although glanders has been eradicated from many parts of the world, the threat of B. mallei being used as a weapon is very real. Here we present draft genome assemblies of 8 Burkholderia mallei strains that were isolated in Turkey.

3.
Nat Nanotechnol ; 11(3): 253-7, 2016 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-26657787

RESUMEN

The detection and characterization of paramagnetic species by electron spin resonance (ESR) spectroscopy is widely used throughout chemistry, biology and materials science, from in vivo imaging to distance measurements in spin-labelled proteins. ESR relies on the inductive detection of microwave signals emitted by the spins into a coupled microwave resonator during their Larmor precession. However, such signals can be very small, prohibiting the application of ESR at the nanoscale (for example, at the single-cell level or on individual nanoparticles). Here, using a Josephson parametric microwave amplifier combined with high-quality-factor superconducting microresonators cooled at millikelvin temperatures, we improve the state-of-the-art sensitivity of inductive ESR detection by nearly four orders of magnitude. We demonstrate the detection of 1,700 bismuth donor spins in silicon within a single Hahn echo with unit signal-to-noise ratio, reduced to 150 spins by averaging a single Carr-Purcell-Meiboom-Gill sequence. This unprecedented sensitivity reaches the limit set by quantum fluctuations of the electromagnetic field instead of thermal or technical noise, which constitutes a novel regime for magnetic resonance. The detection volume of our resonator is ∼ 0.02 nl, and our approach can be readily scaled down further to improve sensitivity, providing a new versatile toolbox for ESR at the nanoscale.


Asunto(s)
Amplificadores Electrónicos , Espectroscopía de Resonancia por Spin del Electrón/instrumentación , Espectroscopía de Resonancia por Spin del Electrón/métodos , Microquímica/instrumentación , Nanopartículas/análisis , Nanopartículas/química , Aire Acondicionado/instrumentación , Síndrome de Creutzfeldt-Jakob , Diseño de Equipo , Análisis de Falla de Equipo , Microondas , Miniaturización , Teoría Cuántica , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Relación Señal-Ruido
4.
Nat Mater ; 14(5): 490-4, 2015 May.
Artículo en Inglés | MEDLINE | ID: mdl-25799326

RESUMEN

Electrical detection of spins is an essential tool for understanding the dynamics of spins, with applications ranging from optoelectronics and spintronics, to quantum information processing. For electron spins bound to donors in silicon, bulk electrically detected magnetic resonance has relied on coupling to spin readout partners such as paramagnetic defects or conduction electrons, which fundamentally limits spin coherence times. Here we demonstrate electrical detection of donor electron spin resonance in an ensemble by transport through a silicon device, using optically driven donor-bound exciton transitions. We measure electron spin Rabi oscillations, and obtain long electron spin coherence times, limited only by the donor concentration. We also experimentally address critical issues such as non-resonant excitation, strain, and electric fields, laying the foundations for realizing a single-spin readout method with relaxed magnetic field and temperature requirements compared with spin-dependent tunnelling, enabling donor-based technologies such as quantum sensing.

5.
Genome Announc ; 2(5)2014 Oct 30.
Artículo en Inglés | MEDLINE | ID: mdl-25359907

RESUMEN

Shigella flexneri causes shigellosis, severe and potentially life-threatening diarrhea, and accounts for 18% of shigellosis cases in the United States. Here, we present the 4.51-Mbp genome assembly of S. flexneri ATCC 12022, a quality control and reference strain, in 10 scaffolds.

6.
Genome Announc ; 2(6)2014 Nov 20.
Artículo en Inglés | MEDLINE | ID: mdl-25414490

RESUMEN

Burkholderia is a genus of betaproteobacteria that includes three notable human pathogens: B. cepacia, B. pseudomallei, and B. mallei. While B. pseudomallei and B. mallei are considered potential biowarfare agents, B. cepacia infections are largely limited to cystic fibrosis patients. Here, we present 56 Burkholderia genomes from 8 distinct species.

7.
Genome Announc ; 2(5)2014 Oct 09.
Artículo en Inglés | MEDLINE | ID: mdl-25301645

RESUMEN

Bacilli are genetically and physiologically diverse, ranging from innocuous to highly pathogenic. Here, we present annotated genome assemblies for 20 strains belonging to Bacillus anthracis, B. atrophaeus, B. cereus, B. licheniformis, B. macerans, B. megaterium, B. mycoides, and B. subtilis.

8.
Genome Announc ; 2(5)2014 Oct 02.
Artículo en Inglés | MEDLINE | ID: mdl-25278527

RESUMEN

Staphylococcus aureus is a major cause of bacterial infections in the United States, with high percentages of serious infections resistant to a variety of ß-lactam antibiotics. Here, we present the scaffolded genome assembly into 16 contigs of S. aureus CDC73-57501 (ATCC 29247), a methicillin-resistant quality control strain.

9.
Genome Announc ; 2(5)2014 Oct 23.
Artículo en Inglés | MEDLINE | ID: mdl-25342679

RESUMEN

Yersinia spp. are animal pathogens, some of which cause human disease. We sequenced 10 Yersinia isolates (from six species: Yersinia enterocolitica, Y. fredericksenii, Y. kristensenii, Y. pestis, Y. pseudotuberculosis, and Y. ruckeri) to high-quality draft or complete status. The genomes range in size from 3.77 to 4.94 Mbp.

10.
Genome Announc ; 2(5)2014 Oct 23.
Artículo en Inglés | MEDLINE | ID: mdl-25342682

RESUMEN

Soft-tissue infection by Pasteurella multocida in humans is usually associated with a dog- or cat-related injury, and these infections can become aggressive. We sequenced the type strain P. multocida subsp. multocida ATCC 43137 into a single closed chromosome consisting of 2,271,840 bp (40.4% G+C content), which is currently available in the NCBI GenBank under the accession number CP008918.

11.
Genome Announc ; 2(5)2014 Sep 25.
Artículo en Inglés | MEDLINE | ID: mdl-25291763

RESUMEN

Klebsiella pneumoniae is a common cause of antibiotic-resistant bacterial infections in immunocompromised individuals. Here, we present the 5.54-Mb scaffolded assembly of the type strain K. pneumoniae type strain ATCC 13883, as deposited in GenBank under accession no. JOOW00000000.

12.
Genome Announc ; 2(5)2014 Sep 18.
Artículo en Inglés | MEDLINE | ID: mdl-25237024

RESUMEN

Brucella species are intracellular zoonotic pathogens which cause, among other pathologies, increased rates of abortion in ruminants. Human infections are generally associated with exposure to contaminated and unpasteurized dairy products; however Brucellae have been developed as bioweapons. Here we present 17 complete and 7 scaffolded genome assemblies of Brucella strains.

13.
Genome Announc ; 2(5)2014 Sep 18.
Artículo en Inglés | MEDLINE | ID: mdl-25237025

RESUMEN

We present the scaffolded genome of Bordetella bronchiseptica ATCC 10580, assembled into 98 contigs. This 5.1-Mb assembly (68.2% G+C content) contains 4,870 coding regions. The strain was originally isolated from canine lung tissue and is used in quality control testing.

14.
Genome Announc ; 2(5)2014 Sep 18.
Artículo en Inglés | MEDLINE | ID: mdl-25237030

RESUMEN

Generally an opportunistic pathogen in the United States, Moraxella catarrhalis has acquired resistance to multiple antibacterial/antimicrobial agents. Here, we present the complete 1.9-Mb genome of M. catarrhalis strain ATCC 25240, as deposited in NCBI under the accession number CP008804.

15.
Genome Announc ; 2(5)2014 Sep 25.
Artículo en Inglés | MEDLINE | ID: mdl-25258272

RESUMEN

We present the genome assembly of Ralstonia pickettii K-288 (ATCC 27511), consisting of 27 contigs placed into a single scaffold. This 4.76-Mbp genome has 64.0% G+C content and 4,425 coding sequences. Because this is the type strain, inclusion of its data set among other Ralstonia genomes should provide a historical genomic perspective.

16.
Phys Rev Lett ; 110(5): 057601, 2013 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-23414045

RESUMEN

We demonstrate an all-electrical donor nuclear spin polarization method in silicon by exploiting the tunable interaction of donor bound electrons with a two-dimensional electron gas, and achieve over two orders of magnitude nuclear hyperpolarization at T=5 K and B=12 T with an in-plane magnetic field. We also show an intricate dependence of nuclear polarization effects on the orientation of the magnetic field, and both hyperpolarization and antipolarization can be controllably achieved in the quantum Hall regime. Our results demonstrate that donor nuclear spin qubits can be initialized through local gate control of electrical currents without the need for optical excitation, enabling the implementation of nuclear spin qubit initialization in dense multiqubit arrays.

17.
Phys Rev Lett ; 106(20): 207601, 2011 May 20.
Artículo en Inglés | MEDLINE | ID: mdl-21668263

RESUMEN

We have measured the electrically detected magnetic resonance of donor-doped silicon field-effect transistors in resonant X- (9.7 GHz) and W-band (94 GHz) microwave cavities. The two-dimensional electron gas resonance signal increases by 2 orders of magnitude from X to W band, while the donor resonance signals are enhanced by over 1 order of magnitude. Bolometric effects and spin-dependent scattering are inconsistent with the observations. We propose that polarization transfer from the donor to the two-dimensional electron gas is the main mechanism giving rise to the spin resonance signals.

18.
Hernia ; 15(6): 655-8, 2011 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-21691736

RESUMEN

PURPOSE: This retrospective chart review was designed to compare outcomes for open and laparoscopic repair of inguinal hernias in the population over the age of 80. METHODS: A retrospective chart review was conducted for 104 patients over 80 years old who underwent inguinal hernia repair (2005-2008) at The Mount Sinai Medical Center. Patients were grouped into laparoscopic or open repair cohorts and compared accordingly. RESULTS: The open group (n = 73) and the laparoscopic group (n = 31) had mean ages of 84 and 83 years, respectively. The mean American Society of Anesthesiologists score was 2.6 for the open cohort and 2.3 for the laparoscopic group (P < 0.05). Peri-operative complications in the open and laparoscopic groups were not found to be statistically significant. There was no mortality in either group. CONCLUSIONS: With octogenarians, laparoscopic inguinal hernia repair can be performed as a safe alternative to open repair with comparable rates of morbidity and mortality.


Asunto(s)
Hernia Inguinal/cirugía , Herniorrafia/efectos adversos , Herniorrafia/métodos , Anciano de 80 o más Años , Anestesia General , Arritmias Cardíacas/etiología , Femenino , Humanos , Hipotensión/etiología , Laparoscopía , Tiempo de Internación , Masculino , Dolor Postoperatorio/etiología , Estudios Retrospectivos , Factores de Tiempo , Resultado del Tratamiento , Retención Urinaria/etiología
19.
Rev Sci Instrum ; 82(3): 034704, 2011 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-21456773

RESUMEN

We describe a low-temperature sample probe for the electrical detection of magnetic resonance in a resonant W-band (94 GHz) microwave cavity. The advantages of this approach are demonstrated by experiments on silicon field-effect transistors. A comparison with conventional low-frequency measurements at X-band (9.7 GHz) on the same devices reveals an up to 100-fold enhancement of the signal intensity. In addition, resonance lines that are unresolved at X-band are clearly separated in the W-band measurements. Electrically detected magnetic resonance at high magnetic fields and high microwave frequencies is therefore a very sensitive technique for studying electron spins with an enhanced spectral resolution and sensitivity.

20.
Mol Oral Microbiol ; 25(6): 391-405, 2010 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-21040513

RESUMEN

Human dental plaque is a complex microbial community containing an estimated 700 to 19,000 species/phylotypes. Despite numerous studies analysing species richness in healthy and diseased human subjects, the true genomic composition of the human dental plaque microbiota remains unknown. Here we report a metagenomic analysis of a healthy human plaque sample using a combination of second-generation sequencing platforms. A total of 860 million base pairs of non-human sequences were generated. Various analysis tools revealed the presence of 12 well-characterized phyla, members of the TM-7 and BRC1 clade, and sequences that could not be classified. Both pathogens and opportunistic pathogens were identified, supporting the ecological plaque hypothesis for oral diseases. Mapping the metagenomic reads to sequenced reference genomes demonstrated that 4% of the reads could be assigned to the sequenced species. Preliminary annotation identified genes belonging to all known functional categories. Interestingly, although 73% of the total assembled contig sequences were predicted to code for proteins, only 51% of them could be assigned a functional role. Furthermore, ~2.8% of the total predicted genes coded for proteins involved in resistance to antibiotics and toxic compounds, suggesting that the oral cavity is an important reservoir for antimicrobial resistance.


Asunto(s)
Placa Dental/microbiología , Genoma Bacteriano/genética , Metagenoma/genética , Análisis de Secuencia de ADN , Actinobacteria/clasificación , Bacterias/clasificación , Proteínas Bacterianas/genética , Bacteroidetes/clasificación , Mapeo Cromosómico , Mapeo Contig/métodos , Cianobacterias/clasificación , Bases de Datos de Ácidos Nucleicos , Farmacorresistencia Bacteriana/genética , Ecosistema , Fibrobacter/clasificación , Fusobacterias/clasificación , Tracto Gastrointestinal/microbiología , Humanos , Metagenómica/métodos , Proteobacteria/clasificación , ARN Bacteriano/genética , ARN Ribosómico 16S/genética , Spirochaetaceae/clasificación
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