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1.
Nano Lett ; 24(40): 12353-12360, 2024 Oct 09.
Artículo en Inglés | MEDLINE | ID: mdl-39351895

RESUMEN

The experimental demonstration of a p-type 2D WSe2 transistor with a ferroelectric perovskite BaTiO3 gate oxide is presented. The 30 nm thick BaTiO3 gate stack shows a robust ferroelectric hysteresis with a remanent polarization of 20 µC/cm2 and further enables a capacitance equivalent thickness of 0.5 nm in the hybrid WSe2/BaTiO3 stack due to its high dielectric constant of 323. We demonstrate one of the best ON currents for perovskite gate 2D transistors in the literature. This is enabled by high-quality epitaxial growth of BaTiO3 and a single 2D layer transfer based fabrication method that is shown to be amenable to silicon platforms. This demonstration is an important milestone toward the integration of crystalline complex oxides with 2D channel materials for scaled CMOS and low-voltage ferroelectric logic applications.

2.
Sci Adv ; 10(41): eado9094, 2024 Oct 11.
Artículo en Inglés | MEDLINE | ID: mdl-39383228

RESUMEN

Fast, high-fidelity, and quantum nondemolition (QND) qubit readout is an essential element of quantum information processing. For superconducting qubits, state-of-the-art readout is based on a dispersive cross-Kerr coupling between a qubit and its readout resonator. The resulting readout can be high fidelity and QND, but readout times are currently limited to the order of 50 nanoseconds due to the dispersive cross-Kerr of magnitude 10 megahertz. Here, we present a readout scheme that uses the quarton coupler to facilitate a large (greater than 200 megahertz) cross-Kerr between a transmon qubit and its readout resonator. Full master equation simulations of the coupled system show a 5-nanosecond readout time with greater than 99% readout fidelity and greater than 99.9% QND fidelity. The quartonic readout circuit is experimentally feasible and preserves the coherence properties of the qubit. Our work reveals a path for order of magnitude improvements of superconducting qubit readout by engineering nonlinear light-matter couplings in parameter regimes unreachable by existing designs.

4.
Phys Rev Lett ; 127(5): 050502, 2021 Jul 30.
Artículo en Inglés | MEDLINE | ID: mdl-34397252

RESUMEN

Strong nonlinear coupling of superconducting qubits and/or photons is a critical building block for quantum information processing. Because of the perturbative nature of the Josephson nonlinearity, linear coupling is often used in the dispersive regime to approximate nonlinear coupling. However, this dispersive coupling is weak and the underlying linear coupling mixes the local modes, which, for example, distributes unwanted self-Kerr nonlinearity to photon modes. Here, we use the quarton to yield purely nonlinear coupling between two linearly decoupled transmon qubits. The quarton's zero ϕ^{2} potential enables an ultrastrong gigahertz-level cross-Kerr coupling, which is an order of magnitude stronger compared to existing schemes, and the quarton's positive ϕ^{4} potential can cancel the negative self-Kerr nonlinearity of qubits to linearize them into resonators. This ultrastrong cross-Kerr coupling between bare modes of qubit-qubit, qubit-photon, and even photon-photon is ideal for applications such as single microwave photon detection, ultrafast two-qubit gates, and readout.

5.
BMJ Open ; 3(5)2013 May 28.
Artículo en Inglés | MEDLINE | ID: mdl-23793671

RESUMEN

OBJECTIVES: Neisseria gonorrhoeae (GC) and Chlamydia trachomatis (CT) can facilitate transmission of HIV. Men who have sex with men (MSM) may harbour infections at genital and extragenital sites. Data regarding extragenital GC and CT infections in military populations are lacking. We examined the prevalence and factors associated with asymptomatic GC and CT infection among this category of HIV-infected military personnel. DESIGN: Cross-sectional cohort study (pilot). SETTING: Infectious diseases clinic at a single military treatment facility in San Diego, CA. PARTICIPANTS: Ninety-nine HIV-positive men were evaluated-79% men who had sex with men, mean age 31 years, 36% black and 33% married. INCLUSION CRITERIA: male, HIV-infected, Department of Defense beneficiary. EXCLUSION CRITERIA: any symptom related to the urethra, pharynx or rectum. PRIMARY OUTCOME MEASURES: GC and CT screening results. RESULTS: Twenty-four per cent were infected with either GC or CT. Rectal swabs were positive in 18% for CT and 3% for GC; pharynx swabs were positive in 8% for GC and 2% for CT. Only one infection was detected in the urine (GC). Anal sex (p=0.04), male partner (OR 7.02, p=0.04) and sex at least once weekly (OR 3.28, p=0.04) were associated with infection. Associated demographics included age <35 years (OR 6.27, p=0.02), non-Caucasian ethnicity (p=0.03), <3 years since HIV diagnosis (OR 2.75, p=0.04) and previous sexually transmitted infection (STI) (OR 5.10, p=0.001). CONCLUSIONS: We found a high prevalence of extragenital GC/CT infection among HIV-infected military men. Only one infection was detected in the urine, signalling the need for aggressive three-site screening of MSM. Clinicians should be aware of the high prevalence in order to enhance health through comprehensive STI screening practices.

7.
ACS Nano ; 5(8): 6096-101, 2011 Aug 23.
Artículo en Inglés | MEDLINE | ID: mdl-21766785

RESUMEN

The evolution of electronic structure of graphene nanoribbons (GNRs) as a function of the number of layers stacked together is investigated using ab initio density functional theory (DFT), including interlayer van der Waals interactions. Multilayer armchair GNRs (AGNRs), similar to single-layer AGNRs, exhibit three classes of band gaps depending on their width. In zigzag GNRs (ZGNRs), the geometry relaxation resulting from interlayer interactions plays a crucial role in determining the magnetic polarization and the band structure. The antiferromagnetic (AF) interlayer coupling is more stable compared to the ferromagnetic (FM) interlayer coupling. ZGNRs with the AF in-layer and AF interlayer coupling have a finite band gap, while ZGNRs with the FM in-layer and AF interlayer coupling do not have a band gap. The ground state of the bilayer ZGNR is nonmagnetic with a small but finite band gap. The magnetic ordering is less stable in multilayer ZGNRs compared to that in single-layer ZGNRs. The quasiparticle GW corrections are smaller for bilayer GNRs compared to single-layer GNRs because of the reduced Coulomb effects in bilayer GNRs compared to single-layer GNRs.

8.
J Nanosci Nanotechnol ; 10(11): 7108-12, 2010 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-21137875

RESUMEN

In this study, we report the development of a microenvironment probe station capable of detecting the effect of small changes to the local environment around a carbon nanotube conduction channel. The microenvironment probe station is highly versatile and is used to characterize alterations in carbon nanotube field effect transistor electrical behavior in response to changes in temperature, gas species, infrared and ultraviolet light. All devices were electrically characterized in atmospheric, ultrahigh vacuum and oxygen-rich environments. The results suggest that devices could be changed from n-type at 1 x 10(-8) torr through an intermediate ambipolar state at 1 x 10(-4) torr to p-type at atmosphere solely by increasing the oxygen concentration. The average resistance of these carbon nanotube field effect transistors after annealing was observed to decrease by approximately 54% from their initial value under ultrahigh vacuum to their final value in the presence of pure oxygen while corresponding threshold voltages shifts were also observed. Illumination with infrared light resulted in a approximately 10% increase in drain current with an estimated response time <1 fs due to photon-induced electron-hole pair generation. Illumination with ultraviolet light resulted in approximately 5-15% reduction in drain current due to photon-induced desorption of oxygen adsorbate.

9.
Nano Lett ; 9(10): 3398-405, 2009 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-19719143

RESUMEN

Growth of vertically aligned carbon nanotube (CNT) carpets on metallic substrates at low temperatures was achieved by controlled thermal treatment of ethylene and hydrogen at a temperature higher than the substrate temperature. High-resolution transmission electron microscopy showed that nanotubes were crystalline for a preheating temperature of 770 degrees C and a substrate temperature of 500 degrees C. Conductive atomic force microscopy measurements indicated electrical contact through the CNT carpet to the metallic substrate with an approximate resistance of 35 kOmega for multiwall carpets taller than two micrometers. An analysis of the activation energies indicated that thermal decomposition of the hydrocarbon/hydrogen gas mixture was the rate-limiting step for low-temperature chemical vapor deposition growth of CNTs. These results represent a significant advance toward the goal of replacing copper interconnects with nanotubes using CMOS-compatible processes.

10.
J Am Chem Soc ; 131(9): 3128-9, 2009 Mar 11.
Artículo en Inglés | MEDLINE | ID: mdl-19222157

RESUMEN

We directly compared ensemble spectroscopic measurements to a statistically rigorous single molecule electrical characterization of individual SWNT devices using a high throughput electrical probe station and reported, for the first time, a highly accurate extinction coefficient ratio for metallic to semiconducting SWNTs of 0.352 +/- 0.009. The systematic counting of metallic and semiconducting types from solution also allows us to examine the variances associated with device properties and therefore provide the first measure of potential defect generation during processing methods.


Asunto(s)
Electrones , Nanotubos de Carbono/química , Espectrometría Raman
11.
Acta Derm Venereol ; 85(1): 2-8, 2005.
Artículo en Inglés | MEDLINE | ID: mdl-15848982

RESUMEN

The PSORS1 locus in the major histocompatibility complex region on chromosome 6p21.3 contains a major predisposing factor for psoriasis for which several candidate genes have been tested. The analyses are complicated by strong linkage disequilibrium in the region and the complex genetic background of psoriasis. In the search for an alternative to HLA-C we have identified a novel gene, PSORS1C3, and characterized it with regard to psoriasis. PSORS1C3 is located approximately 7 kb centromeric to POU5F1. A putative protein of 58 amino acids was predicted and expression was detected in both normal and psoriasis skin. Sequencing of the coding region revealed a total of 11 single nucleotide polymorphisms. When comparing the frequencies of PSORS1C3 variants in a case-control material in the Swedish population, three single nucleotide polymorphisms displayed significant association with psoriasis. This association appeared to be HLA-Cw*0602-dependent due to linkage disequilibrium, thus HLA-C remains the strongest associating factor in the region.


Asunto(s)
Cromosomas Humanos Par 6 , Predisposición Genética a la Enfermedad , Antígenos HLA-C/genética , Psoriasis/genética , Adolescente , Adulto , Anciano , Estudios de Casos y Controles , Niño , Preescolar , Femenino , Humanos , Lactante , Masculino , Persona de Mediana Edad , Polimorfismo de Nucleótido Simple , Psoriasis/etnología , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Análisis de Secuencia de ADN , Suecia/epidemiología
12.
Nucleic Acids Res ; 33(Database issue): D476-80, 2005 Jan 01.
Artículo en Inglés | MEDLINE | ID: mdl-15608241

RESUMEN

The Inparanoid eukaryotic ortholog database (http://inparanoid.cgb.ki.se/) is a collection of pairwise ortholog groups between 17 whole genomes; Anopheles gambiae, Caenorhabditis briggsae, Caenorhabditis elegans, Drosophila melanogaster, Danio rerio, Takifugu rubripes, Gallus gallus, Homo sapiens, Mus musculus, Pan troglodytes, Rattus norvegicus, Oryza sativa, Plasmodium falciparum, Arabidopsis thaliana, Escherichia coli, Saccharomyces cerevisiae and Schizosaccharomyces pombe. Complete proteomes for these genomes were derived from Ensembl and UniProt and compared pairwise using Blast, followed by a clustering step using the Inparanoid program. An Inparanoid cluster is seeded by a reciprocally best-matching ortholog pair, around which inparalogs (should they exist) are gathered independently, while outparalogs are excluded. The ortholog clusters can be searched on the website using Ensembl gene/protein or UniProt identifiers, annotation text or by Blast alignment against our protein datasets. The entire dataset can be downloaded, as can the Inparanoid program itself.


Asunto(s)
Bases de Datos Genéticas , Genómica , Animales , Análisis por Conglomerados , Sistemas de Administración de Bases de Datos , Células Eucariotas/química , Humanos , Internet , Ratones , Ratas , Homología de Secuencia , Interfaz Usuario-Computador
13.
Hum Mutat ; 24(2): 112-9, 2004 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-15241792

RESUMEN

One of the greatest promises of genome sequencing projects is to further the understanding of human diseases and to develop new therapies. Model organism genomes have been sequenced in parallel to human genomes to provide effective tools for the investigation of human gene function. Many of their genes share a common ancestry and function with human genes, and this is particularly true for orthologous genes. Here we present OrthoDisease, a comprehensive database of model organism genes that are orthologous to human disease genes. OrthoDisease was constructed by applying the Inparanoid ortholog detection algorithm to disease genes derived from the Online Mendelian Inheritance in Man database (OMIM). Pairwise whole genome/proteome comparisons between Homo sapiens and six other organisms were performed to identify ortholog clusters. OMIM numbers were extracted from the OMIM Morbid Map and were converted to gene sequences using the Locuslink mim2loc and loc2acc tables. These were mapped to Inparanoid ortholog clusters using Blast. The number of ortholog clusters in OrthoDisease with each respective species is currently: M. musculus, 1,354; D. melanogaster, 724; C. elegans, 533; A. thaliana, 398; S. cerevisiae, 290; and E. coli, 153. The database is accessible online at http://orthodisease.cgb.ki.se, and can be searched with disease or protein names. The web interface presents all ortholog clusters that include a selected disease gene. A capability to download the entire dataset is also provided.


Asunto(s)
Bases de Datos Genéticas/tendencias , Animales , Arabidopsis/genética , Caenorhabditis elegans/genética , Análisis por Conglomerados , Bases de Datos Genéticas/estadística & datos numéricos , Modelos Animales de Enfermedad , Drosophila melanogaster/genética , Escherichia coli/genética , Evolución Molecular , Enfermedades Genéticas Congénitas/genética , Genoma , Genoma Bacteriano , Genoma Fúngico , Genoma Humano , Genoma de Planta , Humanos , Ratones , Proteoma/genética , Saccharomyces cerevisiae/genética , Diseño de Software
14.
Exp Dermatol ; 13(7): 413-8, 2004 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-15217361

RESUMEN

Psoriasis is a chronic inflammatory skin disease that is known to have a strong genetic predisposition. Several psoriasis-susceptibility loci have been previously found through genomic scans. Of these, psoriasis-susceptibility region 1 (PSORS1) on chromosome 6p21 remains the most consistently identified region across populations with the highest association with disease. STG is a gene that was previously isolated from rhesus monkey taste buds, and its ortholog in humans was found to be part of the cluster of genes in PSORS1, which is telomeric to HLA-C. Upon characterization of STG, we identified several sequence variants and investigated their association with psoriasis in cases and controls from the Swedish population. None of these STG single-nucleotide polymorphisms were found to be significantly associated with psoriasis. However, HLA-Cw*0602 status was strongly associated with disease. STG expression was investigated in human tissues and found not to be restricted to taste buds, with signals also being detected in skin and tonsils.


Asunto(s)
Proteínas de la Membrana/biosíntesis , Psoriasis/genética , Línea Celular Tumoral , Cromosomas Humanos Par 6 , Predisposición Genética a la Enfermedad , Variación Genética , Genotipo , Antígenos HLA-C/genética , Humanos , Queratinocitos/metabolismo , Proteínas de la Membrana/genética , Modelos Genéticos , Familia de Multigenes , Oligonucleótidos/química , Tonsila Palatina/metabolismo , Tonsila Palatina/patología , Reacción en Cadena de la Polimerasa , Polimorfismo de Nucleótido Simple , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Piel/metabolismo , Piel/patología , Suecia , Papilas Gustativas/metabolismo , Factores de Tiempo
15.
Exp Dermatol ; 12(4): 435-44, 2003 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-12930300

RESUMEN

Psoriasis is a chronic skin disease that results in red and scaly lesions. Several psoriasis susceptibility loci have been identified across the genome, of which PSORS1 on 6p21.3 is predominant. There is an ongoing debate regarding whether the HLA-C allele, Cw*0602, can be considered the major predisposing factor in this region. Investigation of other genes in the PSORS1 region with regard to psoriasis may provide alternate candidates to HLA-C. We have characterized two overlapping genes, SEEK1 and SPR1. SEEK1 encodes two putative protein isoforms: the first being one of 152 amino acids from the full-length splice-isoform (exon 1-6), and the second being one of 100 amino acids from an alternate splice-isoform (exon 1 and 6). SPR1 encodes a highly conserved protein of 134 amino acids, and in addition to characterization of human SPR1 we report the cloning of its orthologs in mouse and pig. Both SEEK1 and SPR1 are expressed in normal and psoriasis skin. In a case-control study, five of the nine single nucleotide polymorphisms (SNPs) found in SEEK1 were associated with psoriasis, while one of the four SNPs found in SPR1 showed association. Testing the Cw*0602 confounding status revealed that two of the SEEK1 SNPs showed Cw*0602-independent association, while the SPR1 SNP showed Cw*0602-dependent association. The second exon of SEEK1, containing the two Cw*0602-independent SNPs, showed the highest concentration of the psoriasis-associating SNPs, but did not appear to be translated.


Asunto(s)
Cromosomas Humanos Par 6/genética , Polimorfismo de Nucleótido Simple , Proteínas/genética , Psoriasis/genética , Adolescente , Adulto , Anciano , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Estudios de Casos y Controles , Niño , Preescolar , Mapeo Cromosómico , Clonación Molecular , Proteínas Ricas en Prolina del Estrato Córneo , ADN Complementario/genética , Femenino , Expresión Génica , Antígenos HLA-C/genética , Humanos , Lactante , Masculino , Proteínas de la Membrana , Ratones , Persona de Mediana Edad , Datos de Secuencia Molecular , Isoformas de Proteínas/genética , Homología de Secuencia de Aminoácido , Sus scrofa , Suecia
16.
Exp Dermatol ; 11(6): 584-91, 2002 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-12473066

RESUMEN

Neutrophil gelatinase-associated lipocalin (NGAL) is a 25-kDa protein initially isolated from the specific granules of human neutrophils. It is a member of the highly heterogeneous lipocalin protein family, which shares a common tertiary structure. Its synthesis is induced in gastrointestinal epithelium in association with inflammation and malignancy. To gain insight into its potential role in other epithelia we have investigated the expression of NGAL in human skin embryonic development, in normal adult skin, and in skin associated with inflammation and neoplastic transformation. In the present study we report that the embryonic expression of NGAL appears to be regulated in a spatio-temporal pattern. It was induced in the interfollicular epidermis at 20-24 weeks of gestational age but thereafter progressively receded towards the hair follicles. In normal adult skin, NGAL was detected solely in association with hair follicles. However, strong induction of NGAL in the epidermis was seen in a variety of skin disorders characterized by dysregulated epithelial differentiation such as psoriasis, pityriasis rubra and squamous cell carcinoma. In these tissues production of NGAL was confined to spatially distinct subpopulations of keratinocytes underlying areas of parakeratosis, whereas skin samples lacking parakeratotic epithelium such as lichen ruber planus, acute contact eczema and basal cell carcinoma were negative for NGAL. Consistent with being a marker for disturbed terminal differentiation, NGAL immunoreactivity showed an inverse pattern when compared with that of the differentiation marker filaggrin. The biologic functions of NGAL in epithelia are not fully known, although an immunomodulatory role in host defense has been proposed. In addition, the transient interfollicular NGAL expression during skin embryogenesis along with the induction of NGAL in adult parakeratotic epidermis suggests it play a role in epithelial differentiation pathways.


Asunto(s)
Proteínas de Fase Aguda , Proteínas Portadoras/metabolismo , Queratinocitos/metabolismo , Queratinocitos/patología , Proteínas Oncogénicas , Enfermedades de la Piel/metabolismo , Enfermedades de la Piel/patología , Biomarcadores , Proteínas Portadoras/genética , Diferenciación Celular/fisiología , Células Cultivadas , Epidermis/metabolismo , Epidermis/patología , Feto/fisiología , Proteínas Filagrina , Folículo Piloso/metabolismo , Humanos , Lipocalina 2 , Lipocalinas , Metaloproteinasa 9 de la Matriz/metabolismo , Proteínas Proto-Oncogénicas , ARN Mensajero/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Piel/embriología , Piel/metabolismo
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