Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 457
Filtrar
1.
Space Sci Rev ; 220(6): 68, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-39234211

RESUMEN

There is ample evidence for magnetic reconnection in the solar system, but it is a nontrivial task to visualize, to determine the proper approaches and frames to study, and in turn to elucidate the physical processes at work in reconnection regions from in-situ measurements of plasma particles and electromagnetic fields. Here an overview is given of a variety of single- and multi-spacecraft data analysis techniques that are key to revealing the context of in-situ observations of magnetic reconnection in space and for detecting and analyzing the diffusion regions where ions and/or electrons are demagnetized. We focus on recent advances in the era of the Magnetospheric Multiscale mission, which has made electron-scale, multi-point measurements of magnetic reconnection in and around Earth's magnetosphere.

2.
Sci Rep ; 14(1): 21681, 2024 09 17.
Artículo en Inglés | MEDLINE | ID: mdl-39289469

RESUMEN

Undifferentiated pleomorphic sarcoma (UPS) is the largest subgroup of soft tissue sarcomas. This study determined the value of perfusion-weighted imaging with dynamic-contrast-enhancement (PWI/DCE) morphologic, qualitative, and semiquantitative features for predicting UPS pathology-assessed treatment effect (PATE). This retrospective study included 33 surgically excised extremity UPS patients with pre-surgical MRI. Volumetric tumor segmentation from PWI/DCE was obtained at Baseline (BL), Post-Chemotherapy (PC), and Post-Radiation Therapy (PRT). The surgical specimens' PATE separated cases into Responders (R) (≥ 90%, 16 patients), Partial-Responders (PR) (89 - 31%, 10 patients), and Non-Responders (NR) (≤ 30%, seven patients). Seven semiquantitative kinetic parameters and maps were extracted from time-intensity curves (TICs), and 107 radiomic features were derived. Statistical analyses compared R vs. PR/NR. At PRT, 79% of R displayed a "Capsular" morphology (P = 1.49 × 10-7), and 100% demonstrated a TIC-type II (P = 8.32 × 10-7). 80% of PR showed "Unipolar" morphology (P = 1.03 × 10-5), and 60% expressed a TIC-type V (P = 0.06). Semiquantitative wash-in rate (WiR) was able to separate R vs. PR/NR (P = 0.0078). The WiR radiomics displayed significant differences in the first_order_10 percentile (P = 0.0178) comparing R vs. PR/NR at PRT. The PWI/DCE TIC-type II curve, low WiR, and "Capsular" enhancement represent PRT patterns typically observed in successfully treated UPS and demonstrate potential for UPS treatment response assessment.


Asunto(s)
Medios de Contraste , Sarcoma , Humanos , Femenino , Masculino , Persona de Mediana Edad , Anciano , Adulto , Estudios Retrospectivos , Sarcoma/diagnóstico por imagen , Sarcoma/terapia , Sarcoma/patología , Sarcoma/radioterapia , Resultado del Tratamiento , Imagen por Resonancia Magnética/métodos , Anciano de 80 o más Años , Radiómica
3.
J Hosp Infect ; 149: 108-118, 2024 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-38782057

RESUMEN

BACKGROUND: In Taiwan, sequence type (ST) 239 and ST59 were two major clones among meticillin-resistant Staphylococcus aureus (MRSA) clinical isolates in the past two decades. USA300 (ST8) prevailed in the Americas but not in outside areas. Recently USA300 (ST8) emerged and was increasingly identified in Taiwan; we thus conducted an island-wide study to explore the role of USA300 among MRSA isolates. METHODS: One hundred MRSA bloodstream isolates identified in 2020 from each of the six participating hospitals in Taiwan were collected and characterized. The first 10 ST8 isolates from each hospital were further analysed by whole-genome sequencing. RESULTS: Of the 590 confirmed MRSA isolates, a total of 22 pulsotypes and 21 STs were identified. The strain of pulsotype AI/ST8 was the most common lineage identified, accounting for 187 isolates (31.7%) and dominating in five of six hospitals, followed by pulsotype A/ST239 (14.7%), pulsotype C/ST59 (13.9%) and pulsotype D/ST59 (9.2%). Of the 187 pulsotype AI/ST8 isolates, 184 isolates were characterized as USA300 and clustered in three major sub-pulsotypes, accounting for 78%. Ninety per cent of the 60 ST8 isolates for whole-genome sequencing were clustered in three major clades. CONCLUSIONS: In 2020, USA300 became the most common clone of MRSA in Taiwan, accounting for >30% of MRSA bloodstream isolates island wide. Most of USA300 isolates circulating in Taiwan might have been imported on multiple occasions and evolved into at least three successful local clades. MRSA USA300 has successfully established its role in Taiwan, an area outside of the Americas.


Asunto(s)
Genotipo , Staphylococcus aureus Resistente a Meticilina , Infecciones Estafilocócicas , Secuenciación Completa del Genoma , Staphylococcus aureus Resistente a Meticilina/genética , Staphylococcus aureus Resistente a Meticilina/clasificación , Staphylococcus aureus Resistente a Meticilina/aislamiento & purificación , Taiwán/epidemiología , Humanos , Infecciones Estafilocócicas/microbiología , Infecciones Estafilocócicas/epidemiología , Epidemiología Molecular , Hospitales/estadística & datos numéricos , Bacteriemia/microbiología , Bacteriemia/epidemiología , Tipificación Molecular
4.
Artículo en Inglés | MEDLINE | ID: mdl-37327667

RESUMEN

Considerable costs are associated with infertility treatment, but little evidence is available on the main drivers of treatment costs. This cost analysis investigated key costs for treatment with assisted reproductive technology (ART) and the proportion of costs attributed to the acquisition of recombinant human follicle-stimulating hormone (r-hFSH) alfa originator for one fresh embryo transfer (ET) leading to a live birth in Spain, Norway, the UK, Germany, Denmark, South Korea, Australia, and New Zealand. The total costs for one ART cycle with a fresh ET leading to a live birth varied between countries (€4108-€12,314). Costs for pregnancy and live birth were the major contributors in European countries, and the costs of oocyte retrieval, monitoring during ovarian stimulation, pregnancy, and live birth were the top contributors in the Asia-Pacific countries, included in this analysis. Acquisition costs for r-hFSH alfa originator contributed to only 5%-17% of the total costs of one ART cycle with one fresh ET leading to a live birth.


Asunto(s)
Hormona Folículo Estimulante Humana , Nacimiento Vivo , Embarazo , Femenino , Humanos , Embarazo Múltiple , Fertilidad , Inducción de la Ovulación , Costos y Análisis de Costo , Índice de Embarazo , Fertilización In Vitro
5.
Sci Total Environ ; 859(Pt 1): 160249, 2023 Feb 10.
Artículo en Inglés | MEDLINE | ID: mdl-36402337

RESUMEN

For Detroit Michigan the arrival of COVID-19 led to intensive measures to prevent further spread of the virus resulting in consequent changes in traffic and energy use. We take advantage of these different emission scenarios to explore CO2 dynamics in a postindustrial city with a declining population and increasing green space. We present atmospheric CO2 concentration and net urban ecosystem exchange of CO2 (NUE) from a typical eddy covariance system and canopy greenness from a field camera on the Wayne State University campus in midtown Detroit. We categorized our study period (January 18, 2020-July 31, 2020) into three subperiods associated with the state-wide shelter-in-place order. Our results support that the city was a net carbon source throughout the period, particularly during the shelter-in-place period, although reduced traffic lowered CO2 concentrations and NUE. However, during the post-order period when traffic was highest, atmospheric CO2 concentrations and NUE were lowest, suggesting that the greening of urban vegetation may have greater carbon mitigation potential than lowering anthropogenic carbon emissions through traffic reductions.


Asunto(s)
COVID-19 , Carbono , Humanos , Ecosistema , Dióxido de Carbono , Parques Recreativos , Pandemias , Estaciones del Año
6.
J Geophys Res Space Phys ; 128(3): e2022JA031092, 2023 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-38440152

RESUMEN

We present in-depth analysis of three southward-moving meso-scale (ion-to magnetohydrodynamic-scale) flux transfer events (FTEs) and subsequent crossing of a reconnecting magnetopause current sheet (MPCS), which were observed on 8 December 2015 by the Magnetospheric Multiscale spacecraft in the subsolar region under southward and duskward magnetosheath magnetic field conditions. We aim to understand the generation mechanism of ion-scale magnetic flux ropes (ISFRs) and to reveal causal relationship among magnetic field structures, electromagnetic energy conversion, and kinetic processes in magnetic reconnection layers. Results from magnetic field reconstruction methods are consistent with a flux rope with a length of about one ion inertial length growing from an electron-scale current sheet (ECS) in the MPCS, supporting the idea that ISFRs can be generated through secondary reconnection in an ECS. Grad-Shafranov reconstruction applied to the three FTEs shows that the FTEs had axial orientations similar to that of the ISFR. This suggests that these FTEs also formed through the same secondary reconnection process, rather than multiple X-line reconnection at spatially separated locations. Four-spacecraft observations of electron pitch-angle distributions and energy conversion rate j·E'=j·E+ve×B suggest that the ISFR had three-dimensional magnetic topology and secondary reconnection was patchy or bursty. Previously reported positive and negative values of j·E', with magnitudes much larger than expected for typical MP reconnection, were seen in both magnetosheath and magnetospheric separatrix regions of the ISFR. Many of them coexisted with bi-directional electron beams and intense electric field fluctuations around the electron gyrofrequency, consistent with their origin in separatrix activities.

7.
J Geophys Res Space Phys ; 127(7): e2022JA030408, 2022 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-36248013

RESUMEN

We present observations in Earth's magnetotail by the Magnetospheric Multiscale spacecraft that are consistent with magnetic field annihilation, rather than magnetic topology change, causing fast magnetic-to-electron energy conversion in an electron-scale current sheet. Multi-spacecraft analysis for the magnetic field reconstruction shows that an electron-scale magnetic island was embedded in the observed electron diffusion region (EDR), suggesting an elongated shape of the EDR. Evidence for the annihilation was revealed in the form of the island growing at a rate much lower than expected for the standard X-type geometry of the EDR, which indicates that magnetic flux injected into the EDR was not ejected from the X-point or accumulated in the island, but was dissipated in the EDR. This energy conversion process is in contrast to that in the standard EDR of a reconnecting current sheet where the energy of antiparallel magnetic fields is mostly converted to electron bulk-flow energy. Fully kinetic simulation also demonstrates that an elongated EDR is subject to the formation of electron-scale magnetic islands in which fast but transient annihilation can occur. Consistent with the observations and simulation, theoretical analysis shows that fast magnetic diffusion can occur in an elongated EDR in the presence of nongyrotropic electron effects. We suggest that the annihilation in elongated EDRs may contribute to the dissipation of magnetic energy in a turbulent collisionless plasma.

8.
Eur Rev Med Pharmacol Sci ; 26(16): 5844-5856, 2022 08.
Artículo en Inglés | MEDLINE | ID: mdl-36066160

RESUMEN

OBJECTIVE: Mycoplasma pneumoniae (M. pneumoniae) pneumonia is the second-most common cause of community-acquired pneumonia (CAP). This study aimed at investigating into the prevalence of macrolide-resistant M. pneumoniae (MRMP) with respiratory virus co-infection and the antibiotic prescriptions in children with CAP in four provinces in Korea, and to assess the variations in the findings across regions and throughout the year. PATIENTS AND METHODS: This prospective study was conducted in 29 hospitals in Korea between July 2018 and June 2020. Among the enrolled 1,063 children with CAP, all 451 patients with M. pneumoniae underwent PCR assays of M. pneumoniae and respiratory viruses, and the presence of point mutations of residues 2063 and 2064 was evaluated. RESULTS: Gwangju-Honam (88.6%) showed the highest prevalence of MRMP pneumonia, while Daejeon-Chungcheong (71.3%) showed the lowest, although the differences in prevalence were not significant (p=0.074). Co-infection of M. pneumoniae pneumonia and respiratory virus was observed in 206 patients (45.4%), and rhinovirus co-infection (101 children; 22.2%) was the most frequent. The prevalence of MRMP pneumonia with respiratory virus co-infection and the antibiotic prescriptions differed significantly among the four provinces (p < 0.05). The monthly rate of MRMP pneumonia cases among all cases of M. pneumoniae pneumonia and tetracycline or quinolone prescriptions did not differ significantly among the four regions (trend p > 0.05) during the study period. CONCLUSIONS: The prevalence of M. pneumoniae pneumonia with virus co-infection and antibiotic prescriptions could differ according to region, although the MRMP pneumonia rate showed no difference within Korea.


Asunto(s)
Coinfección , Infecciones Comunitarias Adquiridas , Neumonía por Mycoplasma , Virosis , Virus , Antibacterianos/farmacología , Antibacterianos/uso terapéutico , Niño , Coinfección/complicaciones , Coinfección/tratamiento farmacológico , Coinfección/epidemiología , Farmacorresistencia Bacteriana , Humanos , Macrólidos/uso terapéutico , Mycoplasma pneumoniae/genética , Neumonía por Mycoplasma/tratamiento farmacológico , Neumonía por Mycoplasma/epidemiología , Prescripciones , Estudios Prospectivos , Virosis/tratamiento farmacológico
9.
J Assist Reprod Genet ; 39(9): 2103-2114, 2022 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-35849255

RESUMEN

PURPOSE: To identify clinically significant genomic copy number (CNV) and single nucleotide variants (SNV) in males with unexplained spermatogenic failure (SPGF). MATERIALS AND METHODS: Peripheral blood DNA from 97/102 study participants diagnosed with oligozoospermia, severe oligozoospermia, or non-obstructive azoospermia (NOA) was analyzed for CNVs via array comparative genomic hybridization (aCGH) and SNVs using whole-exome sequencing (WES). RESULTS: Of the 2544 CNVs identified in individuals with SPGF, > 90% were small, ranging from 0.6 to 75 kb. Thirty, clinically relevant genomic aberrations, were detected in 28 patients (~ 29%). These included likely diagnostic CNVs in 3/41 NOA patients (~ 7%): 1 hemizygous, intragenic TEX11 deletion, 1 hemizygous DDX53 full gene deletion, and 1 homozygous, intragenic STK11 deletion. High-level mosaicism for X chromosome disomy (~ 10% 46,XY and ~ 90% 47,XXY) was also identified in 3 of 41 NOA patients who previously tested normal with conventional karyotyping. The remaining 24 CNVs detected were heterozygous, autosomal recessive carrier variants. Follow-up WES analysis confirmed 8 of 27 (30%) CNVs (X chromosome disomy excluded). WES analysis additionally identified 13 significant SNVs and/or indels in 9 patients (~ 9%) including X-linked AR, KAL1, and NR0B1 variants. CONCLUSION: Using a combined genome-wide aCGH/WES approach, we identified pathogenic and likely pathogenic SNVs and CNVs in 15 patients (15%) with unexplained SPGF. This value equals the detection rate of conventional testing for aneuploidies and is considerably higher than the prevalence of Y chromosome microdeletions. Our results underscore the importance of comprehensive genomic analysis in emerging diagnostic testing of complex conditions like male infertility.


Asunto(s)
Variaciones en el Número de Copia de ADN , Oligospermia , Azoospermia , Hibridación Genómica Comparativa , Variaciones en el Número de Copia de ADN/genética , Pruebas Genéticas/métodos , Secuenciación de Nucleótidos de Alto Rendimiento , Humanos , Masculino , Nucleótidos , Oligospermia/diagnóstico , Oligospermia/genética
10.
Nat Commun ; 13(1): 2954, 2022 May 26.
Artículo en Inglés | MEDLINE | ID: mdl-35618713

RESUMEN

Coulomb collisions provide plasma resistivity and diffusion but in many low-density astrophysical plasmas such collisions between particles are extremely rare. Scattering of particles by electromagnetic waves can lower the plasma conductivity. Such anomalous resistivity due to wave-particle interactions could be crucial to many processes, including magnetic reconnection. It has been suggested that waves provide both diffusion and resistivity, which can support the reconnection electric field, but this requires direct observation to confirm. Here, we directly quantify anomalous resistivity, viscosity, and cross-field electron diffusion associated with lower hybrid waves using measurements from the four Magnetospheric Multiscale (MMS) spacecraft. We show that anomalous resistivity is approximately balanced by anomalous viscosity, and thus the waves do not contribute to the reconnection electric field. However, the waves do produce an anomalous electron drift and diffusion across the current layer associated with magnetic reconnection. This leads to relaxation of density gradients at timescales of order the ion cyclotron period, and hence modifies the reconnection process.

12.
BJOG ; 128(11): 1762-1773, 2021 10.
Artículo en Inglés | MEDLINE | ID: mdl-34173998

RESUMEN

OBJECTIVE: Stillbirths occur 10-20 times more frequently in low-income settings compared with high-income settings. We created a methodology to define the proportion of stillbirths that are potentially preventable in low-income settings and applied it to stillbirths in sites in India and Pakistan. DESIGN: Prospective observational study. SETTING: Three maternity hospitals in Davangere, India and a large public hospital in Karachi, Pakistan. POPULATION: All cases of stillbirth at ≥20 weeks of gestation occurring from July 2018 to February 2020 were screened for participation; 872 stillbirths were included in this analysis. METHODS: We prospectively defined the conditions and gestational ages that defined the stillbirth cases considered potentially preventable. Informed consent was sought from the parent(s) once the stillbirth was identified, either before or soon after delivery. All information available, including obstetric and medical history, clinical course, fetal heart sounds on admission, the presence of maceration as well as examination of the stillbirth after delivery, histology, and polymerase chain reaction for infectious pathogens of the placenta and various fetal tissues, was used to assess whether a stillbirth was potentially preventable. MAIN OUTCOME MEASURES: Whether a stillbirth was determined to be potentially preventable and the criteria for assignment to those categories. RESULTS: Of 984 enrolled, 872 stillbirths at ≥20 weeks of gestation met the inclusion criteria and were included; of these, 55.5% were deemed to be potentially preventable. Of the 649 stillbirths at ≥28 weeks of gestation and ≥1000 g birthweight, 73.5% were considered potentially preventable. The most common conditions associated with a potentially preventable stillbirth at ≥28 weeks of gestation and ≥1000 g birthweight were small for gestational age (SGA) (52.8%), maternal hypertension (50.2%), antepartum haemorrhage (31.4%) and death that occurred after hospital admission (15.7%). CONCLUSIONS: Most stillbirths in these sites were deemed preventable and were often associated with maternal hypertension, antepartum haemorrhage, SGA and intrapartum demise. TWEETABLE ABSTRACT: Most stillbirths are preventable by better care for women with hypertension, growth restriction and antepartum haemorrhage.


Asunto(s)
Muerte Fetal/prevención & control , Atención Prenatal/estadística & datos numéricos , Calidad de la Atención de Salud/estadística & datos numéricos , Mortinato/epidemiología , Adulto , Femenino , Edad Gestacional , Humanos , India/epidemiología , Recién Nacido , Recién Nacido Pequeño para la Edad Gestacional , Complicaciones del Trabajo de Parto/epidemiología , Pakistán/epidemiología , Embarazo , Atención Prenatal/normas , Estudios Prospectivos
13.
Anaesthesia ; 76(1): 54-60, 2021 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-32592515

RESUMEN

Pre-operative anaemia (haemoglobin < 13.0 g.dl-1 ) is a modifiable peri-operative risk-factor. This is screened for using formal laboratory testing. A non-invasive finger-probe sensor that can accurately measure haemoglobin is a possible alternative. This study considers the accuracy of non-invasive haemoglobin measurement using the Rad-67™ Rainbow (Masimo Corp., Irvine, CA, USA) compared with formal laboratory testing and its usefulness in detecting pre-operative anaemia. A total of 392 patients had measurements taken for non-invasive haemoglobin and perfusion index values using the Rad-67 Rainbow, alongside further peri-operative parameters and a formal laboratory haemoglobin test. Bland-Altman and sensitivity analysis showed that the limits of agreement between non-invasive and formal laboratory haemoglobin testing were between -1.95 g.dl-1 and 2.23 g.dl-1 (p < 0.001). The overall performance of non-invasive haemoglobin measurement was better in men than women (ROC 91.1% vs. 78.2%) and less biased in men, mean -0.08 (SD 1.09, 95%Cl -0.23-0.07) compared with women (mean 0.38 (SD 0.99, 95%CI 0.24-0.52)). Pre-operative anaemia was more prevalent in women than men (50.3% vs. 14.4%). The sensitivity of non-invasive anaemia detection (haemoglobin < 13 g.dl-1 ) was 66% for women and 52% for men. A non-invasive haemoglobin value of 14.0 g.dl-1 had an overall 91% sensitivity for detecting pre-operative anaemia (82% in men and 93% in women). The Rad-67 Rainbow is inadequate for the estimation of formal laboratory haemoglobin and lacks sensitivity for detecting pre-operative anaemia, especially in women. Further advancement in technology and accuracy is needed before it can be recommended as a routine pre-operative screening test.


Asunto(s)
Anemia/diagnóstico , Hemoglobinometría/métodos , Oximetría/métodos , Cuidados Preoperatorios/métodos , Adulto , Anciano , Anemia/epidemiología , Femenino , Humanos , Masculino , Tamizaje Masivo , Persona de Mediana Edad , Perfusión , Estudios Prospectivos , Curva ROC , Factores Sexuales
14.
Geophys Res Lett ; 47(13): e2020GL087574, 2020 Jul 16.
Artículo en Inglés | MEDLINE | ID: mdl-32999512

RESUMEN

At the Earth's low-latitude magnetopause, clear signatures of the Kelvin-Helmholtz (KH) waves have been frequently observed during periods of the northward interplanetary magnetic field (IMF), whereas these signatures have been much less frequently observed during the southward IMF. Here, we performed the first 3-D fully kinetic simulation of the magnetopause KH instability under the southward IMF condition. The simulation demonstrates that fast magnetic reconnection is induced at multiple locations along the vortex edge in an early nonlinear growth phase of the instability. The reconnection outflow jets significantly disrupt the flow of the nonlinear KH vortex, while the disrupted turbulent flow strongly bends and twists the reconnected field lines. The resulting coupling of the complex field and flow patterns within the magnetopause boundary layer leads to a quick decay of the vortex structure, which may explain the difference in the observation probability of KH waves between northward and southward IMF conditions.

15.
J Physiol Pharmacol ; 71(3)2020 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-32991314

RESUMEN

Canine cloning is occasionally accompanied by abnormal sexual development. Some male donor cells produce cloned pups with female external genitalia and complete male gonadal dysgenesis, which is classified as an XY disorder of sex development (XY DSD). In this study, we examine the potential of 5-aza-2'-deoxycytidine (5-aza-dC), a DNA methyltransferase inhibitor, to reduce the phenotypic abnormality XY DSD in somatic cell nuclear transfer (SCNT)- derived pups. We used a 9-year-old normal male German Shepherd dog as a cell donor. Donor cells were treated with 10 nM 5-aza-dC for 4 days before being used for SCNT. At the same stage of cell development, significantly lower levels of DNA methylation of the sex-determining region Y (SRY) promoter was observed in the treated donor cells compared to that in the untreated cells (95.2% versus 53.3% on day 4 for the control and treated groups, respectively). No significant differences were observed in the control or treatment groups concerning fusion rate, pregnancy rate (30 days or entire period), the number of pups, or the incidence of XY DSD. However, more XY DSD dogs were observed in the control group (31.25%) than in the treatment group (14.29%). Hypermethylation of the SRY promoter was observed in the XY DSD cloned pups in both the treatment (84.8%) and control groups (91.1 ± 1.4%) compared to the methylation level in the phenotypically normal male pups of the treatment (23.2 ± 20.9%) and control groups (39.1 ± 20.1%). These results suggest that 5-aza-dC treatment of donor cells can reduce the methylation level of the SRY promoter in donor cells, and thus, 5-aza-dC is advantageous for reducing the incidence of XY DSD in canine cloning.


Asunto(s)
Clonación Molecular , Metilación de ADN , Enfermedades de los Perros/genética , Disgenesia Gonadal 46 XY/veterinaria , Técnicas de Transferencia Nuclear/veterinaria , Regiones Promotoras Genéticas , Procesos de Determinación del Sexo/genética , Proteína de la Región Y Determinante del Sexo/genética , Animales , Metilación de ADN/efectos de los fármacos , Metilasas de Modificación del ADN/antagonistas & inhibidores , Metilasas de Modificación del ADN/metabolismo , Decitabina/farmacología , Enfermedades de los Perros/tratamiento farmacológico , Enfermedades de los Perros/patología , Perros , Inhibidores Enzimáticos/farmacología , Predisposición Genética a la Enfermedad , Disgenesia Gonadal 46 XY/tratamiento farmacológico , Disgenesia Gonadal 46 XY/genética , Disgenesia Gonadal 46 XY/patología , Masculino , Técnicas de Transferencia Nuclear/efectos adversos , Fenotipo , Regiones Promotoras Genéticas/efectos de los fármacos
16.
J Geophys Res Space Phys ; 125(4): e2019JA027665, 2020 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-32714734

RESUMEN

On 5 May 2017, MMS observed a crater-type flux rope on the dawnside tailward magnetopause with fluctuations. The boundary-normal analysis shows that the fluctuations can be attributed to nonlinear Kelvin-Helmholtz (KH) waves. Reconnection signatures such as flow reversals and Joule dissipation were identified at the leading and trailing edges of the flux rope. In particular, strong northward electron jets observed at the trailing edge indicated midlatitude reconnection associated with the 3-D structure of the KH vortex. The scale size of the flux rope, together with reconnection signatures, strongly supports the interpretation that the flux rope was generated locally by KH vortex-induced reconnection. The center of the flux rope also displayed signatures of guide-field reconnection (out-of-plane electron jets, parallel electron heating, and Joule dissipation). These signatures indicate that an interface between two interlinked flux tubes was undergoing interaction, causing a local magnetic depression, resulting in an M-shaped crater flux rope, as supported by reconstruction.

17.
Phys Rev Lett ; 124(4): 045101, 2020 Jan 31.
Artículo en Inglés | MEDLINE | ID: mdl-32058767

RESUMEN

We report electrostatic Debye-scale turbulence developing within the diffusion region of asymmetric magnetopause reconnection with a moderate guide field using observations by the Magnetospheric Multiscale mission. We show that Buneman waves and beam modes cause efficient and fast thermalization of the reconnection electron jet by irreversible phase mixing, during which the jet kinetic energy is transferred into thermal energy. Our results show that the reconnection diffusion region in the presence of a moderate guide field is highly turbulent, and that electrostatic turbulence plays an important role in electron heating.

18.
Geophys Res Lett ; 46(12): 6287-6296, 2019 Jun 28.
Artículo en Inglés | MEDLINE | ID: mdl-31598018

RESUMEN

While vorticity defined as the curl of the velocity has been broadly used in fluid and plasma physics, this quantity has been underutilized in space physics due to low time resolution observations. We report Magnetospheric Multiscale (MMS) observations of enhanced electron vorticity in the vicinity of the electron diffusion region of magnetic reconnection. On 11 July 2017 MMS traversed the magnetotail current sheet, observing tailward-to-earthward outflow reversal, current-carrying electron jets in the direction along the electron meandering motion or out-of-plane direction, agyrotropic electron distribution functions, and dissipative signatures. At the edge of the electron jets, the electron vorticity increased with magnitudes greater than the electron gyrofrequency. The out-of-plane velocity shear along distance from the current sheet leads to the enhanced vorticity. This, in turn, contributes to the magnetic field perturbations observed by MMS. These observations indicate that electron vorticity can act as a proxy for delineating the electron diffusion region of magnetic reconnection.

19.
Technol Cancer Res Treat ; 18: 1533033819873629, 2019 01 01.
Artículo en Inglés | MEDLINE | ID: mdl-31551011

RESUMEN

In adaptive radiation therapy of head and neck cancer, any significant anatomical changes observed are used to adapt the treatment plan to maintain target coverage without elevating the risk of xerostomia. However, the additional resources required for adaptive radiation therapy pose a challenge for broad-based implementation. It is hypothesized that a change in transit fluence is associated with volumetric change in the vicinity of the target and therefore can be used as a decision support metric for adaptive radiation therapy. This was evaluated by comparing the fluence with volumetric changes in 12 patients. Transit fluence was measured by an in vivo portal dosimetry system. Weekly cone beam computed tomography was used to determine volume change in the rectangular region of interest from condyloid process to C6. The integrated transit fluence through the region of interest on the day of the cone beam computed tomography scan was calculated with the first treatment as the baseline. The correlation between fluence change and volume change was determined. A logistic regression model was also used to associate the 5% region of interest volume reduction replanning trigger point and the fluence change. The model was assessed by a chi-square test. The area under the receiver-operating characteristic curve was also determined. A total of 46 pairs of measurements were obtained. The correlation between fluence and volumetric changes was found to be -0.776 (P value <.001). The negative correlation is attributed to the increase in the photon fluence transport resulting from the volume reduction. The chi-square of the logistic regression was found to be 17.4 (P value <.001). The area under the receiver-operating characteristic curve was found to be 0.88. Results indicate the change in transit fluence, which can be measured without consuming clinical resources or requiring additional time in the treatment room, can be used as a decision support metric for adaptive therapy.


Asunto(s)
Sistemas de Apoyo a Decisiones Clínicas , Neoplasias de Cabeza y Cuello/radioterapia , Radiometría , Planificación de la Radioterapia Asistida por Computador , Algoritmos , Toma de Decisiones Clínicas , Tomografía Computarizada de Haz Cónico/métodos , Tomografía Computarizada de Haz Cónico/normas , Manejo de la Enfermedad , Neoplasias de Cabeza y Cuello/diagnóstico , Humanos , Curva ROC , Radiometría/métodos , Dosificación Radioterapéutica , Planificación de la Radioterapia Asistida por Computador/métodos , Resultado del Tratamiento
20.
Proc Natl Acad Sci U S A ; 116(33): 16186-16191, 2019 Aug 13.
Artículo en Inglés | MEDLINE | ID: mdl-31350347

RESUMEN

Spin-orbit coupling (SOC), the interaction between the electron spin and the orbital angular momentum, can unlock rich phenomena at interfaces, in particular interconverting spin and charge currents. Conventional heavy metals have been extensively explored due to their strong SOC of conduction electrons. However, spin-orbit effects in classes of materials such as epitaxial 5d-electron transition-metal complex oxides, which also host strong SOC, remain largely unreported. In addition to strong SOC, these complex oxides can also provide the additional tuning knob of epitaxy to control the electronic structure and the engineering of spin-to-charge conversion by crystalline symmetry. Here, we demonstrate room-temperature generation of spin-orbit torque on a ferromagnet with extremely high efficiency via the spin-Hall effect in epitaxial metastable perovskite SrIrO3 We first predict a large intrinsic spin-Hall conductivity in orthorhombic bulk SrIrO3 arising from the Berry curvature in the electronic band structure. By manipulating the intricate interplay between SOC and crystalline symmetry, we control the spin-Hall torque ratio by engineering the tilt of the corner-sharing oxygen octahedra in perovskite SrIrO3 through epitaxial strain. This allows the presence of an anisotropic spin-Hall effect due to a characteristic structural anisotropy in SrIrO3 with orthorhombic symmetry. Our experimental findings demonstrate the heteroepitaxial symmetry design approach to engineer spin-orbit effects. We therefore anticipate that these epitaxial 5d transition-metal oxide thin films can be an ideal building block for low-power spintronics.

SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA
...