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1.
Nature ; 612(7939): 240-245, 2022 12.
Artículo en Inglés | MEDLINE | ID: mdl-36477133

RESUMEN

Systems of correlated particles appear in many fields of modern science and represent some of the most intractable computational problems in nature. The computational challenge in these systems arises when interactions become comparable to other energy scales, which makes the state of each particle depend on all other particles1. The lack of general solutions for the three-body problem and acceptable theory for strongly correlated electrons shows that our understanding of correlated systems fades when the particle number or the interaction strength increases. One of the hallmarks of interacting systems is the formation of multiparticle bound states2-9. Here we develop a high-fidelity parameterizable fSim gate and implement the periodic quantum circuit of the spin-½ XXZ model in a ring of 24 superconducting qubits. We study the propagation of these excitations and observe their bound nature for up to five photons. We devise a phase-sensitive method for constructing the few-body spectrum of the bound states and extract their pseudo-charge by introducing a synthetic flux. By introducing interactions between the ring and additional qubits, we observe an unexpected resilience of the bound states to integrability breaking. This finding goes against the idea that bound states in non-integrable systems are unstable when their energies overlap with the continuum spectrum. Our work provides experimental evidence for bound states of interacting photons and discovers their stability beyond the integrability limit.

2.
Nature ; 594(7864): 508-512, 2021 06.
Artículo en Inglés | MEDLINE | ID: mdl-34163052

RESUMEN

A promising approach to study condensed-matter systems is to simulate them on an engineered quantum platform1-4. However, the accuracy needed to outperform classical methods has not been achieved so far. Here, using 18 superconducting qubits, we provide an experimental blueprint for an accurate condensed-matter simulator and demonstrate how to investigate fundamental electronic properties. We benchmark the underlying method by reconstructing the single-particle band structure of a one-dimensional wire. We demonstrate nearly complete mitigation of decoherence and readout errors, and measure the energy eigenvalues of this wire with an error of approximately 0.01 rad, whereas typical energy scales are of the order of 1 rad. Insight into the fidelity of this algorithm is gained by highlighting the robust properties of a Fourier transform, including the ability to resolve eigenenergies with a statistical uncertainty of 10-4 rad. We also synthesize magnetic flux and disordered local potentials, which are two key tenets of a condensed-matter system. When sweeping the magnetic flux we observe avoided level crossings in the spectrum, providing a detailed fingerprint of the spatial distribution of local disorder. By combining these methods we reconstruct electronic properties of the eigenstates, observing persistent currents and a strong suppression of conductance with added disorder. Our work describes an accurate method for quantum simulation5,6 and paves the way to study new quantum materials with superconducting qubits.

3.
J Bacteriol ; 203(22): e0036721, 2021 10 25.
Artículo en Inglés | MEDLINE | ID: mdl-34516280

RESUMEN

The bacterial flagellar motor (BFM) is a protein complex that confers motility to cells and contributes to survival and virulence. The BFM consists of stators that are ion-selective membrane protein complexes and a rotor that directly connects to a large filament, acting as a propeller. The stator complexes couple ion transit across the membrane to torque that drives rotation of the motor. The most common ion gradients that drive BFM rotation are protons (H+) and sodium ions (Na+). The sodium-powered stators, like those in the PomA/PomB stator complex of Vibrio spp., can be inhibited by sodium channel inhibitors, in particular, by phenamil, a potent and widely used inhibitor. However, relatively few new sodium motility inhibitors have been described since the discovery of phenamil. In this study, we characterized two possible motility inhibitors, HM2-16F and BB2-50F, from a small library of previously reported amiloride derivatives. We used three approaches: effect on rotation of tethered cells, effect on free-swimming bacteria, and effect on rotation of marker beads. We showed that both HM2-16F and BB2-50F stopped rotation of tethered cells driven by Na+ motors comparable to phenamil at matching concentrations and could also stop rotation of tethered cells driven by H+ motors. Bead measurements in the presence and absence of stators confirmed that the compounds did not inhibit rotation via direct association with the stator, in contrast to the established mode of action of phenamil. Overall, HM2-16F and BB2-50F stopped swimming in both Na+ and H+ stator types and in pathogenic and nonpathogenic strains. IMPORTANCE Here, we characterized two novel amiloride derivatives in the search for antimicrobial compounds that target bacterial motility. These compounds were shown to inhibit flagellar motility at 10 µM across multiple strains: from nonpathogenic Escherichia coli with flagellar rotation driven by proton or chimeric sodium-powered stators, to proton-powered pathogenic E. coli (enterohemorrhagic E. coli or uropathogenic E. coli [EHEC or UPEC, respectively]), and finally, sodium-powered Vibrio alginolyticus. Broad antimotility compounds such as these are important tools in our efforts to control virulence of pathogens in health and agricultural settings.


Asunto(s)
Amilorida/análogos & derivados , Amilorida/farmacología , Escherichia coli/efectos de los fármacos , Escherichia coli/fisiología , Vibrio alginolyticus/efectos de los fármacos , Vibrio alginolyticus/fisiología , Bloqueadores del Canal Iónico Sensible al Ácido/farmacología , Amilorida/química , Escherichia coli/clasificación , Movimiento
4.
Clin Radiol ; 76(9): 640-649, 2021 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-34108098

RESUMEN

Scleroderma is a complex multisystem connective tissue disorder. Early visceral disease, such as gastrointestinal (GI) involvement, is associated with significant morbidity and a poorer prognosis. Prompt diagnosis is crucial to allow disease modifying therapies be initiated early in the course of the disease. The primary underlying pathophysiology in the GI tract is dysmotility, muscular atrophy, and fibrosis, and this is reflected in the imaging features. In this paper, we demonstrate the imaging appearances of involvement of the GI tract and describe the use of advanced imaging with magnetic resonance enterography (MRE). A multimodal imaging approach is required to identify both characteristic features of scleroderma and potential complications. Traditional fluoroscopic contrast (barium) studies are still commonly performed for assessment of the oesophagus. More recent advances in cross-sectional imaging allow for thorough three-dimensional assessment of the entire GI tract. MRE is particularly useful for small bowel evaluation while also allowing "pseudodynamic" functional imaging and concomitant assessment of the other abdominal viscera and structures.


Asunto(s)
Enfermedades Gastrointestinales/diagnóstico por imagen , Enfermedades Gastrointestinales/etiología , Imagen por Resonancia Magnética/métodos , Imagen Multimodal/métodos , Esclerodermia Sistémica/complicaciones , Tomografía Computarizada por Rayos X/métodos , Tracto Gastrointestinal/diagnóstico por imagen , Humanos
5.
Pharmacogenomics J ; 18(2): 215-226, 2018 04.
Artículo en Inglés | MEDLINE | ID: mdl-28719597

RESUMEN

Thiazide diuretics, commonly used antihypertensives, may cause QT interval (QT) prolongation, a risk factor for highly fatal and difficult to predict ventricular arrhythmias. We examined whether common single-nucleotide polymorphisms (SNPs) modified the association between thiazide use and QT or its component parts (QRS interval, JT interval) by performing ancestry-specific, trans-ethnic and cross-phenotype genome-wide analyses of European (66%), African American (15%) and Hispanic (19%) populations (N=78 199), leveraging longitudinal data, incorporating corrected standard errors to account for underestimation of interaction estimate variances and evaluating evidence for pathway enrichment. Although no loci achieved genome-wide significance (P<5 × 10-8), we found suggestive evidence (P<5 × 10-6) for SNPs modifying the thiazide-QT association at 22 loci, including ion transport loci (for example, NELL1, KCNQ3). The biologic plausibility of our suggestive results and simulations demonstrating modest power to detect interaction effects at genome-wide significant levels indicate that larger studies and innovative statistical methods are warranted in future efforts evaluating thiazide-SNP interactions.


Asunto(s)
Envejecimiento/genética , Etnicidad/genética , Genómica/tendencias , Frecuencia Cardíaca/genética , Farmacogenética/tendencias , Inhibidores de los Simportadores del Cloruro de Sodio/farmacología , Adulto , Anciano , Anciano de 80 o más Años , Envejecimiento/efectos de los fármacos , Envejecimiento/etnología , Estudios de Cohortes , Electrocardiografía/efectos de los fármacos , Electrocardiografía/tendencias , Femenino , Genómica/métodos , Frecuencia Cardíaca/efectos de los fármacos , Humanos , Estudios Longitudinales , Masculino , Persona de Mediana Edad , Farmacogenética/métodos , Polimorfismo de Nucleótido Simple/efectos de los fármacos , Polimorfismo de Nucleótido Simple/genética
6.
Haemophilia ; 24(3): e93-e102, 2018 May.
Artículo en Inglés | MEDLINE | ID: mdl-29577531

RESUMEN

INTRODUCTION: Central venous access devices (CVADs) facilitate repeated or urgent treatments for paediatric haemophilia patients, but are associated with complications. This study examined the burden of illness, healthcare utilization and costs for CVADs in a real-world hospital setting. MATERIALS AND METHODS: This study included haemophilia patients ages ≤18 years with discharges during 2006-2014 in the US Premier Healthcare Database. Haemophilia was identified using ICD-9 diagnosis codes and CVAD exposure using billing information. After matching haemophilia patients with and without CVADs on demographic and clinical characteristics, we compared infection, thrombosis, length of stay (LOS), inflation-adjusted hospital cost (2014 $USD) and readmission outcomes using generalized estimating equation models adjusted for hospital teaching status. RESULTS: Among 4793 paediatric haemophilia patients treated at one of 548 hospitals, a total of 197 patients were identified with CVAD exposure. The matched sample included 310 haemophilia patients (155 CVAD and 155 non-CVAD). CVAD cases had greater frequencies of all-cause infections (29% vs 17%, P = .01) and thrombosis (6% vs 1%, P = .06), longer adjusted mean LOS (9.5 vs 4.7 days, P = .002), higher adjusted mean inpatient total hospitalization costs ($47200 vs $25389, P = .02) as well as more inpatient and outpatient visits at 30-, 60- and 90-days (P < .05 for all differences) compared with non-CVAD patients. CONCLUSION: Paediatric haemophilia patients with CVADs experienced greater infection rates, healthcare utilization and higher hospitalization costs compared with non-CVAD patients. The results of this study may inform further research efforts to understand the costs and benefits of novel treatment alternatives for young haemophilia patients requiring CVADs.


Asunto(s)
Catéteres Venosos Centrales , Costo de Enfermedad , Accesibilidad a los Servicios de Salud/estadística & datos numéricos , Hemofilia A/economía , Hemofilia A/terapia , Hospitales , Adolescente , Niño , Preescolar , Femenino , Hemofilia A/complicaciones , Humanos , Lactante , Recién Nacido , Infecciones/complicaciones , Tiempo de Internación , Masculino , Pacientes Ambulatorios , Estudios Retrospectivos , Trombosis/complicaciones , Estados Unidos
7.
Phys Chem Chem Phys ; 20(17): 12037-12042, 2018 May 07.
Artículo en Inglés | MEDLINE | ID: mdl-29671846

RESUMEN

Non-equilibrium radio-frequency driven atmospheric-pressure plasma in He/0.6%O2 gas mixture has been used to study the reaction mechanism of plasma-generated oxygen atoms in aqueous solutions. The effluent from the plasma source operated with standard and 18O-labeled O2 gas was used to treat water in the presence of phenol as a chemical probe. Comparing the mass spectrometry and gas chromatography-mass spectrometry data of the solutions treated with plasma under normal and labeled oxygen provides clear evidence that O(aq) originating from the gas phase enters the liquid and reacts directly with phenol, without any intermediate reactions. Additionally, the atmospheric-pressure plasma source demonstrates great potential to be an effective source of O(aq) atoms without the requirement for any precursors in the liquid phase.

8.
J Public Health (Oxf) ; 40(4): e586-e593, 2018 12 01.
Artículo en Inglés | MEDLINE | ID: mdl-29688551

RESUMEN

Background: Translational research is required to ensure exercise referral schemes (ERSs) are evidence-based and reflect local needs. This article reports process data from the co-development phase of an ERS, providing an insight into (i) factors that must be considered when translating evidence to practice in an ERS setting, and (ii) challenges and facilitators of conducting participatory research involving multiple stakeholders. Methods: An ERS was iteratively co-developed by a multidisciplinary stakeholder group (commissioners, managers, practitioners, patients and academics) via five participatory meetings and an online survey. Audio data (e.g. group discussions) and visual data (e.g. whiteboard notes) were recorded and analysed using NVivo-10 electronic software. Results: Factors to consider when translating evidence to practice in an ERS setting included (i) current ERS culture; (ii) skills, safety and accountability; and (iii) resources and capacity. The co-development process was facilitated by needs-analysis, open questions, multidisciplinary debate and reflective practice. Challenges included contrasting views, irregular attendance and (mis)perceptions of evaluation. Conclusion: The multidisciplinary co-development process highlighted cultural and pragmatic issues related to exercise referral provision, resulting in an evidence-based intervention framework designed to be implemented within existing infrastructures. Further work is required to establish the feasibility and effectiveness of the co-developed intervention in practice.


Asunto(s)
Ejercicio Físico , Derivación y Consulta/organización & administración , Investigación Participativa Basada en la Comunidad , Humanos , Evaluación de Necesidades , Desarrollo de Programa , Encuestas y Cuestionarios , Investigación Biomédica Traslacional
9.
Geophys Res Lett ; 44(10): 5104-5112, 2017 May 28.
Artículo en Inglés | MEDLINE | ID: mdl-29950746

RESUMEN

Volcanic eruptions have global climate impacts, but their effect on the hydrologic cycle is poorly understood. We use a modified version of superposed epoch analysis, an eruption year list collated from multiple datasets, and seasonal paleoclimate reconstructions (soil moisture, precipitation, geopotential heights, and temperature) to investigate volcanic forcing of spring and summer hydroclimate over Europe and the Mediterranean over the last millennium. In the western Mediterranean, wet conditions occur in the eruption year and the following 3 years. Conversely, northwestern Europe and the British Isles experience dry conditions in response to volcanic eruptions, with the largest moisture deficits in post-eruption years 2 and 3. The precipitation response occurs primarily in late spring and early summer (April-July), a pattern that strongly resembles the negative phase of the East Atlantic Pattern. Modulated by this mode of climate variability, eruptions force significant, widespread, and heterogeneous hydroclimate responses across Europe and the Mediterranean.

10.
Indoor Air ; 27(3): 518-528, 2017 05.
Artículo en Inglés | MEDLINE | ID: mdl-27748984

RESUMEN

Superstorm Sandy provided an opportunity to study filamentous fungi (molds) associated with winter storm damage. We collected 36 morphologically distinct fungal isolates from flooded buildings. By combining traditional morphological and cultural characters with an analysis of ITS sequences (the fungal DNA barcode), we identified 24 fungal species that belong to eight genera: Penicillium (11 species), Fusarium (four species), Aspergillus (three species), Trichoderma (two species), and one species each of Metarhizium, Mucor, Pestalotiopsis, and Umbelopsis. Then, we used a Drosophila larval assay to assess possible toxicity of volatile organic compounds (VOCs) emitted by these molds. When cultured in a shared atmosphere with growing cultures of molds isolated after Hurricane Sandy, larval toxicity ranged from 15 to 80%. VOCs from Aspergillus niger 129B were the most toxic yielding 80% mortality to Drosophila after 12 days. The VOCs from Trichoderma longibrachiatum 117, Mucor racemosus 138a, and Metarhizium anisopliae 124 were relatively non-toxigenic. A preliminary analysis of VOCs was conducted using solid-phase microextraction-gas chromatography-mass spectrometry from two of the most toxic, two of the least toxic, and two species of intermediate toxicity. The more toxic molds produced higher concentrations of 1-octen-3-ol, 3-octanone, 3-octanol, 2-octen-1-ol, and 2-nonanone; while the less toxic molds produced more 3-methyl-1-butanol and 2-methyl-1-propanol, or an overall lower amount of volatiles. Our data support the hypothesis that at certain concentrations, some VOCs emitted by indoor molds are toxigenic.


Asunto(s)
Microbiología del Aire , Drosophila/efectos de los fármacos , Hongos/metabolismo , Compuestos Orgánicos Volátiles/análisis , Contaminación del Aire Interior/análisis , Animales , Bioensayo , Tormentas Ciclónicas , Hongos/aislamiento & purificación , Vivienda , Humanos , New Jersey , Microextracción en Fase Sólida , Pruebas de Toxicidad
11.
Mol Psychiatry ; 20(2): 183-92, 2015 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-25644384

RESUMEN

General cognitive function is substantially heritable across the human life course from adolescence to old age. We investigated the genetic contribution to variation in this important, health- and well-being-related trait in middle-aged and older adults. We conducted a meta-analysis of genome-wide association studies of 31 cohorts (N=53,949) in which the participants had undertaken multiple, diverse cognitive tests. A general cognitive function phenotype was tested for, and created in each cohort by principal component analysis. We report 13 genome-wide significant single-nucleotide polymorphism (SNP) associations in three genomic regions, 6q16.1, 14q12 and 19q13.32 (best SNP and closest gene, respectively: rs10457441, P=3.93 × 10(-9), MIR2113; rs17522122, P=2.55 × 10(-8), AKAP6; rs10119, P=5.67 × 10(-9), APOE/TOMM40). We report one gene-based significant association with the HMGN1 gene located on chromosome 21 (P=1 × 10(-6)). These genes have previously been associated with neuropsychiatric phenotypes. Meta-analysis results are consistent with a polygenic model of inheritance. To estimate SNP-based heritability, the genome-wide complex trait analysis procedure was applied to two large cohorts, the Atherosclerosis Risk in Communities Study (N=6617) and the Health and Retirement Study (N=5976). The proportion of phenotypic variation accounted for by all genotyped common SNPs was 29% (s.e.=5%) and 28% (s.e.=7%), respectively. Using polygenic prediction analysis, ~1.2% of the variance in general cognitive function was predicted in the Generation Scotland cohort (N=5487; P=1.5 × 10(-17)). In hypothesis-driven tests, there was significant association between general cognitive function and four genes previously associated with Alzheimer's disease: TOMM40, APOE, ABCG1 and MEF2C.


Asunto(s)
Trastornos del Conocimiento/genética , Cognición/fisiología , Predisposición Genética a la Enfermedad/genética , Proteína HMGN1/genética , Polimorfismo de Nucleótido Simple/genética , Anciano , Anciano de 80 o más Años , Aterosclerosis/complicaciones , Trastornos del Conocimiento/etiología , Estudios de Cohortes , Femenino , Estudio de Asociación del Genoma Completo , Humanos , Masculino , Persona de Mediana Edad , Pruebas Neuropsicológicas , Fenotipo , Escocia
12.
Eur J Clin Pharmacol ; 72(4): 431-7, 2016 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-26686871

RESUMEN

PURPOSE: In pharmacogenetic research, genetic variation in non-responders and high responders is compared with the aim to identify the genetic loci responsible for this variation in response. However, an important question is whether the non-responders are truly biologically non-responsive or actually non-adherent? Therefore, the aim of this study was to describe, within the PROspective Study of Pravastatin in the Elderly at Risk (PROSPER), characteristics of both non-responders and high responders of statin treatment in order to possibly discriminate non-responders from non-adherers. METHODS: Baseline characteristics of non-responders to statin therapy (≤10 % LDL-C reduction) were compared with those of high responders (>40 % LDL-C reduction) through a linear regression analysis. In addition, pharmacogenetic candidate gene analysis was performed to show the effect of excluding non-responders from the analysis. RESULTS: Non-responders to statin therapy were younger (p = 0.001), more often smoked (p < 0.001), had a higher alcohol consumption (p < 0.001), had lower LDL cholesterol levels (p < 0.001), had a lower prevalence of hypertension (p < 0.001), and had lower cognitive function (p = 0.035) compared to subjects who highly responded to pravastatin treatment. Moreover, excluding non-responders from pharmacogenetic studies yielded more robust results, as standard errors decreased. CONCLUSION: Our results suggest that non-responders to statin therapy are more likely to actually be non-adherers, since they have more characteristics that are viewed as indicators of high self-perceived health and low disease awareness, possibly making the subjects less adherent to study medication. We suggest that in pharmacogenetic research, extreme non-responders should be excluded to overcome the problem that non-adherence is investigated instead of non-responsiveness.


Asunto(s)
Inhibidores de Hidroximetilglutaril-CoA Reductasas/uso terapéutico , Anciano , Anciano de 80 o más Años , LDL-Colesterol/sangre , Femenino , Variación Genética/genética , Humanos , Masculino , Farmacogenética/métodos , Pruebas de Farmacogenómica , Pravastatina/uso terapéutico , Estudios Prospectivos , Ensayos Clínicos Controlados Aleatorios como Asunto , Riesgo , Resultado del Tratamiento
13.
Pharmacogenomics J ; 14(1): 6-13, 2014 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-23459443

RESUMEN

Variability in response to drug use is common and heritable, suggesting that genome-wide pharmacogenomics studies may help explain the 'missing heritability' of complex traits. Here, we describe four independent analyses in 33 781 participants of European ancestry from 10 cohorts that were designed to identify genetic variants modifying the effects of drugs on QT interval duration (QT). Each analysis cross-sectionally examined four therapeutic classes: thiazide diuretics (prevalence of use=13.0%), tri/tetracyclic antidepressants (2.6%), sulfonylurea hypoglycemic agents (2.9%) and QT-prolonging drugs as classified by the University of Arizona Center for Education and Research on Therapeutics (4.4%). Drug-gene interactions were estimated using covariable-adjusted linear regression and results were combined with fixed-effects meta-analysis. Although drug-single-nucleotide polymorphism (SNP) interactions were biologically plausible and variables were well-measured, findings from the four cross-sectional meta-analyses were null (Pinteraction>5.0 × 10(-8)). Simulations suggested that additional efforts, including longitudinal modeling to increase statistical power, are likely needed to identify potentially important pharmacogenomic effects.


Asunto(s)
Efectos Colaterales y Reacciones Adversas Relacionados con Medicamentos/genética , Interacción Gen-Ambiente , Síndrome de QT Prolongado/genética , Farmacogenética , Polimorfismo de Nucleótido Simple/genética , Carácter Cuantitativo Heredable , Simulación por Computador , Estudios Transversales , Electrocardiografía , Estudio de Asociación del Genoma Completo , Humanos , Modelos Lineales , Cadenas de Markov , Población Blanca/genética
14.
Science ; 384(6691): 48-53, 2024 Apr 05.
Artículo en Inglés | MEDLINE | ID: mdl-38574139

RESUMEN

Understanding universal aspects of quantum dynamics is an unresolved problem in statistical mechanics. In particular, the spin dynamics of the one-dimensional Heisenberg model were conjectured as to belong to the Kardar-Parisi-Zhang (KPZ) universality class based on the scaling of the infinite-temperature spin-spin correlation function. In a chain of 46 superconducting qubits, we studied the probability distribution of the magnetization transferred across the chain's center, [Formula: see text]. The first two moments of [Formula: see text] show superdiffusive behavior, a hallmark of KPZ universality. However, the third and fourth moments ruled out the KPZ conjecture and allow for evaluating other theories. Our results highlight the importance of studying higher moments in determining dynamic universality classes and provide insights into universal behavior in quantum systems.

15.
Science ; 383(6689): 1332-1337, 2024 Mar 22.
Artículo en Inglés | MEDLINE | ID: mdl-38513021

RESUMEN

Engineered dissipative reservoirs have the potential to steer many-body quantum systems toward correlated steady states useful for quantum simulation of high-temperature superconductivity or quantum magnetism. Using up to 49 superconducting qubits, we prepared low-energy states of the transverse-field Ising model through coupling to dissipative auxiliary qubits. In one dimension, we observed long-range quantum correlations and a ground-state fidelity of 0.86 for 18 qubits at the critical point. In two dimensions, we found mutual information that extends beyond nearest neighbors. Lastly, by coupling the system to auxiliaries emulating reservoirs with different chemical potentials, we explored transport in the quantum Heisenberg model. Our results establish engineered dissipation as a scalable alternative to unitary evolution for preparing entangled many-body states on noisy quantum processors.

16.
Nature ; 448(7150): 180-2, 2007 Jul 12.
Artículo en Inglés | MEDLINE | ID: mdl-17625562

RESUMEN

The flux of nitrogen from land and atmosphere to estuaries and the coastal ocean has increased substantially in recent decades. The observed increase in nitrogen loading is caused by population growth, urbanization, expanding water and sewer infrastructure, fossil fuel combustion and synthetic fertilizer consumption. Most of the nitrogen is removed by denitrification in the sediments of estuaries and the continental shelf, leading to a reduction in both cultural eutrophication and nitrogen pollution of the open ocean. Nitrogen fixation, however, is thought to be a negligible process in sub-tidal heterotrophic marine systems. Here we report sediment core data from Narragansett Bay, USA, which demonstrate that heterotrophic marine sediments can switch from being a net sink to being a net source of nitrogen. Mesocosm and core incubation experiments, together with a historic data set of mean annual chlorophyll production, support the idea that a climate-induced decrease in primary production has led to a decrease in organic matter deposition to the benthos and the observed reversal of the net sediment nitrogen flux. Our results suggest that some estuaries may no longer remove nitrogen from the water column. Instead, nitrogen could be exported to the continental shelf and the open ocean and could shift the effect of anthropogenic nitrogen loading beyond the immediate coastal zone.


Asunto(s)
Ecosistema , Gases/análisis , Sedimentos Geológicos/química , Nitrógeno/metabolismo , Agua de Mar/química , Bacterias/metabolismo , Clorofila/análisis , Clima , Nitrógeno/análisis , Fitoplancton/metabolismo , Estaciones del Año , Estados Unidos , Contaminantes del Agua/análisis
17.
Fam Pract ; 30(1): 105-12, 2013 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-22850249

RESUMEN

BACKGROUND: National policies are being developed, which may limit access to patients' records for health research. This could reduce the ability of health research to benefit society as a whole. It is important to develop an in-depth understanding of people's views across demographic groups to inform such policy development. Aims. To explore patients' views about the use of their general practice records in health research with attention to gender and age. Design of study. Qualitative study using focus groups. SETTING: Six General Practices in the west of Ireland. METHOD: Focus Group interviews with 35 people who were patients at the practices. RESULTS: Overall, participants were positively inclined towards the idea of information from their records (anonymous and identifiable) being used in research for the 'greater good' although there were some concerns about personal information being 'leaked'. Males emphasized risks in relation to employment and finances, whereas females emphasized risks in relation to social discomfort and embarrassment. Participants were supportive of consent models that enable patients to give prior ongoing consent for specific agreed 'levels' of data use, affording patients self-determination without the need for consent request on study-by-study basis. CONCLUSION: Overall male and female patients of different ages are supportive of the use of their general practice records in health research and of general practitioners as data protectors.


Asunto(s)
Actitud , Investigación Biomédica , Confidencialidad , Registros de Salud Personal , Pacientes/psicología , Adolescente , Adulto , Anciano , Femenino , Grupos Focales , Medicina General , Humanos , Irlanda , Masculino , Persona de Mediana Edad , Investigación Cualitativa , Registros , Adulto Joven
18.
Proc Natl Acad Sci U S A ; 107(19): 8513-8, 2010 May 11.
Artículo en Inglés | MEDLINE | ID: mdl-20404195

RESUMEN

Identifying and designing physical systems for use as qubits, the basic units of quantum information, are critical steps in the development of a quantum computer. Among the possibilities in the solid state, a defect in diamond known as the nitrogen-vacancy (NV(-1)) center stands out for its robustness--its quantum state can be initialized, manipulated, and measured with high fidelity at room temperature. Here we describe how to systematically identify other deep center defects with similar quantum-mechanical properties. We present a list of physical criteria that these centers and their hosts should meet and explain how these requirements can be used in conjunction with electronic structure theory to intelligently sort through candidate defect systems. To illustrate these points in detail, we compare electronic structure calculations of the NV(-1) center in diamond with those of several deep centers in 4H silicon carbide (SiC). We then discuss the proposed criteria for similar defects in other tetrahedrally coordinated semiconductors.

19.
Diabet Med ; 29(7): 844-54, 2012 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-22150506

RESUMEN

BACKGROUND: Gestational diabetes mellitus is a potentially serious condition that affects many pregnancies and its prevalence is increasing. Evidence suggests early detection and treatment improves outcomes, but this is hampered by continued disagreement and inconsistency regarding many aspects of its diagnosis. METHODS: The Vitamin D and Lifestyle Intervention for Gestational Diabetes Mellitus Prevention (DALI) research programme aims to promote pan-European standards in the detection and diagnosis of gestational diabetes and to develop effective preventive interventions. To provide an overview of the context within which the programme will be conducted and its findings interpreted, systematic searching and narrative synthesis have been used to identify and review the best available European evidence relating to the prevalence of gestational diabetes, current screening practices and barriers to screening. RESULTS: Prevalence is most often reported as 2-6% of pregnancies. Prevalence may be lower towards the Northern Atlantic seaboard of Europe and higher in the Southern Mediterranean seaboard. Screening practice and policy is inconsistent across Europe, hampered by lack of consensus on testing methods, diagnostic glycaemic thresholds and the value of routine screening. Poor clinician awareness of gestational diabetes, its diagnosis and local clinical guidelines further undermine detection of gestational diabetes. CONCLUSIONS: Europe-wide agreement on screening approaches and diagnostic standards for gestational diabetes could lead to better detection and treatment, improved outcomes for women and children and a strengthened evidence base. There is an urgent need for well-designed research that can inform decisions on best practice in gestational diabetes mellitus screening and diagnosis.


Asunto(s)
Diabetes Gestacional/diagnóstico , Diabetes Gestacional/epidemiología , Embarazo de Alto Riesgo , Diabetes Gestacional/prevención & control , Diagnóstico Precoz , Europa (Continente)/epidemiología , Femenino , Prueba de Tolerancia a la Glucosa/métodos , Humanos , Tamizaje Masivo/métodos , Tamizaje Masivo/normas , Tamizaje Masivo/tendencias , Guías de Práctica Clínica como Asunto , Embarazo , Prevalencia
20.
Placenta ; 121: 99-108, 2022 04.
Artículo en Inglés | MEDLINE | ID: mdl-35305398

RESUMEN

Epidemiological studies have associated ambient engineered nanomaterials or ultrafine particulate matter (PM0.1), collectively referred to as nanoparticles (NPs), with adverse pregnancy outcomes including miscarriage, preterm labor, and fetal growth restriction. Evidence from non-pregnant models demonstrate that NPs can cross the lung air-blood barrier and circulate systemically. Therefore, inhalation of NPs during pregnancy leading to fetoplacental exposure has garnered attention. The purpose of this study was to evaluate the distribution of inhaled titanium dioxide nanoparticles (nano-TiO2) from the maternal lung to maternal and fetal systemic tissues. Pregnant Sprague Dawley rats were administered whole-body exposure to filtered air or of nano-TiO2 aerosols (9.96 ± 0.06 mg/m3) between gestational day (GD) 4 and 19. On GD 20 maternal, placental, and fetal tissues were harvested then digested for ICP-MS analysis to measure concentrations of titanium (Ti). TEM was used to visualize particle internalization by the placental syncytium. The results demonstrate the extrapulmonary distribution of Ti to various maternal organs during pregnancy. Our study found Ti accumulation in the decidua/junctional and labyrinth zones of placentas embedded in all sections of uterine horns. Further, NPs deposited in the placenta, identified by TEM, were found intracellularly within nuclear, endoplasmic reticulum, and vesicle organelles. This study identified the systemic distribution and placental accumulation of Ti after nano-TiO2 aerosol inhalation in a pregnancy model. These findings arouse concerns for poor air quality for pregnant women and possible contributions to adverse pregnancy outcomes.


Asunto(s)
Aborto Espontáneo , Nanopartículas , Animales , Femenino , Feto , Exposición Materna/efectos adversos , Nanopartículas/efectos adversos , Placenta , Embarazo , Ratas , Ratas Sprague-Dawley , Titanio/efectos adversos
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