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1.
Anim Biotechnol ; 34(4): 1594-1602, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-35244514

RESUMO

The present investigation was performed to compare the global gene expression profile in peripheral blood mononuclear cells (PBMCs) of Bos indicus and crossbred (Bos taurus × B. indicus) cattle. Previously, several studies revealed the disease tolerance potential of B. indicus cattle but underlying genetic mechanism is still not fully explored. The PBMCs model was used for this investigation as it plays crucial role in the immune system regulation. Transcriptomic analysis revealed total 6767 significantly differentially expressed transcripts (fold change (absolute) >2.0, p < .05). In addition, 4149 transcripts were upregulated, 2618 transcripts were downregulated and fold change (absolute) of differentially expressed transcript varied from -223.32 to 213.63. Functional annotation analysis of differentially expressed genes confirmed their role in various molecular pathways viz. innate immune response, antigen processing and presentation, MHC protein complex, defense response to bacterium, regulation of immune response, positive regulation of JAK-STAT cascade, cytoskeletal protein binding, etc. Protein-protein interaction network analysis provided understanding of inter-relationship of immune genes with differentially expressed genes. In conclusion, this study could provide comprehensive information about the dysregulated genes and biological pathways in PBMCs which might be responsible for disease tolerance in B. indicus cattle.


Assuntos
Leucócitos Mononucleares , Transcriptoma , Bovinos/genética , Animais , Transcriptoma/genética , Leucócitos Mononucleares/metabolismo , Perfilação da Expressão Gênica/veterinária , Imunidade Inata/genética
2.
Nano Lett ; 21(12): 5083-5090, 2021 Jun 23.
Artigo em Inglês | MEDLINE | ID: mdl-34097421

RESUMO

The intrinsic magnetic topological insulators MnBi2Te4 and MnBi2Se4 support novel topological states related to symmetry breaking by magnetic order. Unlike MnBi2Te4, the study of MnBi2Se4 has been inhibited by the lack of bulk crystals, as the van der Waals (vdW) crystal is not the thermodynamic equilibrium phase. Here, we report the layer-by-layer synthesis of vdW MnBi2Se4 crystals using nonequilibrium molecular beam epitaxy. Atomic-resolution scanning transmission electron microscopy and scanning tunneling microscopy identify a well-ordered vdW crystal with septuple-layer base units. The magnetic properties agree with the predicted layered antiferromagnetic ordering but disagree with its predicted out-of-plane orientation. Instead, our samples exhibit an easy-plane anisotropy, which is explained by including dipole-dipole interactions. Angle-resolved photoemission spectroscopy reveals the gapless Dirac-like surface state, which demonstrates that MnBi2Se4 is a topological insulator above the magnetic-ordering temperature. These studies show that MnBi2Se4 is a promising candidate for exploring rich topological phases of layered antiferromagnetic topological insulators.

3.
Trop Anim Health Prod ; 52(5): 2585-2592, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32445160

RESUMO

Female fertility in domestic animals in India has exhaustively suffered owing to indiscriminate breeding with single objective of increasing milk production. First lactation data on 7782 Mehsana buffaloes sired by 184 bulls maintained under field progeny testing programme at Dudhsagar Research and Development Association, Dudhsagar Dairy, Mehsana, over a period of 24 years were used for study of fertility traits viz. days open, first to successful service period (FTSS) and daughter pregnancy rate (DPR) and production traits viz. first lactation milk yield (FLMY), first lactation fat yield (FLFY) and average fat percentage (AFP). The voluntary waiting period (VWP) was standardised based on the higher estimates for FLMY and FLMY per unit first calving interval. VWP for Mehsana buffaloes was standardised as 63 days after first calving and consequently DPR of Mehsana buffalo was also estimated as 31%. Fertility traits were further evaluated in terms of production traits. Regression analysis revealed that the increase in 1 kg FLFY and 100 kg FLMY led to the increase of First Service Period by 0.013 days and decrease in the DPR by 1.89%, respectively. Increase in milk yield led to increase in FTSS. However, for each 100 kg increase in fat yield and 1% increase in AFP, there is increase in DPR by 0.08% and 0.051%, respectively. Based on the present findings, it may be recommended to have a breeding programme which give due weightage to both production and fertility traits.


Assuntos
Búfalos/fisiologia , Fertilidade/genética , Animais , Búfalos/genética , Colostro , Feminino , Fertilidade/fisiologia , Índia , Lactação , Leite , Gravidez , Taxa de Gravidez , Análise de Regressão
4.
Nano Lett ; 18(5): 3125-3131, 2018 05 09.
Artigo em Inglês | MEDLINE | ID: mdl-29608316

RESUMO

Monolayer van der Waals (vdW) magnets provide an exciting opportunity for exploring two-dimensional (2D) magnetism for scientific and technological advances, but the intrinsic ferromagnetism has only been observed at low temperatures. Here, we report the observation of room temperature ferromagnetism in manganese selenide (MnSe x) films grown by molecular beam epitaxy (MBE). Magnetic and structural characterization provides strong evidence that, in the monolayer limit, the ferromagnetism originates from a vdW manganese diselenide (MnSe2) monolayer, while for thicker films it could originate from a combination of vdW MnSe2 and/or interfacial magnetism of α-MnSe(111). Magnetization measurements of monolayer MnSe x films on GaSe and SnSe2 epilayers show ferromagnetic ordering with a large saturation magnetization of ∼4 Bohr magnetons per Mn, which is consistent with the density functional theory calculations predicting ferromagnetism in monolayer 1T-MnSe2. Growing MnSe x films on GaSe up to a high thickness (∼40 nm) produces α-MnSe(111) and an enhanced magnetic moment (∼2×) compared to the monolayer MnSe x samples. Detailed structural characterization by scanning transmission electron microscopy (STEM), scanning tunneling microscopy (STM), and reflection high energy electron diffraction (RHEED) reveals an abrupt and clean interface between GaSe(0001) and α-MnSe(111). In particular, the structure measured by STEM is consistent with the presence of a MnSe2 monolayer at the interface. These results hold promise for potential applications in energy efficient information storage and processing.

5.
Acad Psychiatry ; 39(1): 47-54, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25034955

RESUMO

OBJECTIVE: Little is known about the efficacy of current interventions to mitigate burnout among medical students and residents, despite its association with mood disorders, absenteeism, low job satisfaction, and medical errors. This review summarizes the efficacy data of burnout interventions and how each modality is used. METHOD: OVID-SP Medline, Google Scholar and PsychINFO were searched for combinations of medical subject headings (MeSH) terms: premedical students, medical students, internships, intern, medical graduate, clinical clerkship, and residents in combination with a keyword group of burnout, professional burnout, suicide, attempted suicide, and prevention. Studies with data on the efficacy from burnout prevention programs were included for review. RESULTS: Nineteen studies were selected for inclusion in this review. Eleven different types of interventions and combinations of interventions were used. There were six studies on the impact of the 2003 duty-hour restrictions by the Accreditation Council for Graduate Medical Education on burnout. Other approaches included self-development groups, conversion to a pass-fail grading system and training in mindfulness, communication, and stress management. Half of the intervention approaches had at least one study demonstrating benefit in reducing burnout. Self-development groups, the Respiratory One Method for relaxation, and conversion to a pass-fail grading system appear to reduce burnout. The burnout data on mindfulness training and the 2003 resident duty-hour restrictions are mixed. There were no studies available on burnout among premedical students or suicide prevention among medical students or residents. CONCLUSIONS: There is a growing body of evidence-based interventions to mitigate burnout which can be used in the development of future programs. More research is needed to identify and intervene against burnout earlier in the medical education pipeline, including at the undergraduate level.


Assuntos
Esgotamento Profissional/terapia , Prática Clínica Baseada em Evidências , Internato e Residência , Médicos/psicologia , Estudantes de Medicina/psicologia , Resultado do Tratamento , Adulto , Esgotamento Profissional/prevenção & controle , Humanos
6.
Opt Express ; 22(9): 11029-34, 2014 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-24921801

RESUMO

Heterojunction devices of Ge(1-x)Sn(x) / n-Ge were grown by solid source molecular beam epitaxy (MBE), and the mid-infrared (IR) photocurrent response was measured. With increasing Sn composition from 4% to 12%, the photocurrent spectra became red-shifted, suggesting that the bandgap of Ge(1-x)Sn(x) alloys was lowered compared to pure Ge. At a temperature of 100 K, the wavelengths of peak photocurrent were shifted from 1.42 µm for pure Ge (0% Sn) to 2.0 µm for 12% Sn. The bias dependence of the device response showed that the optimum reverse bias was > 0.5 volts for saturated photocurrent. The responsivity of the Ge(1-x)Sn(x) devices was estimated to be 0.17 A/W for 4% Sn. These results suggest that Ge(1-x)Sn(x) photodetectors may have practical applications in the near/mid IR wavelength regime.

7.
Nano Lett ; 13(6): 2418-22, 2013 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-23647308

RESUMO

A low-temperature scanning tunneling microscope was used in conjunction with density functional theory calculations to determine the binding sites and charge states of adsorbed Ga and Mn atoms on GaAs(110). To quantify the adatom charge states (both +1e), the Coulomb interaction with an individual Mn acceptor is measured via tunneling spectroscopy and compared with theoretical predictions. Several methods for positioning these charged adatoms are demonstrated, allowing us to engineer the electrostatic landscape of the surface with atomic precision.

8.
Phytomedicine ; 129: 155702, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38749344

RESUMO

BACKGROUND: Non-alcoholic fatty liver disease (NAFLD) is a chronic liver disease with therapeutic options on the horizon. Picrorhiza kurroa, enriched with iridoid glycosides like picroside I and picroside II is known for its hepatoprotective activity and anti-inflammatory properties. Androsin, the other phytochemical present in P. kurroa has been shown to have anti-inflammatory and anti-asthmatic properties. However, its role in NAFLD is yet to be investigated. PURPOSE: This study aims to identify the potent hepatoprotective agent from P. kurroa that can attenuate NAFLD in HFrD-fed ApoE-/- mice, and elucidate the underlying mechanisms governing its effects. METHODS: Classical purification methods were used to isolate seven compounds, including picroside I, picroside II and androsin from the roots of P. kurroa. NAFLD-induced ApoE-/- mice were administered orally with either picroside I, picroside II, or androsin for 7 weeks. Animals were scanned non-invasively by ultrasonography at 1st and 14th week. Gross histomorphometry was examined by HE and Sirius red staining. mRNA transcript and protein profile associated with autophagy, lipogenesis, inflammation, and fibrosis was done through RT-PCR and Western blot analysis. RESULTS: In-vitro and in-vivo studies revealed that among the seven evaluated compounds, androsin shows the most potent in-vitro activity. Oral dosing of androsin (10 mg/kg) protected the liver against HFrD-induced NAFLD in ApoE-/- mice model. Biochemical analysis revealed a reduction in ALT and AST enzymes and a significant reduction in cholesterol levels. Hepatocyte ballooning, hepatic lipid deposition, inflammation, and fibrosis were reduced. Androsin treatment significantly reduced fibrosis (α-SMA, collagens, TGF-ß) and inflammation (ILs, TNF-α, NFκB) in ApoE-/- mice. Mechanistically, androsin activated AMPKα and down-regulated the expression of SREBP-1c, resulting in ameliorating hepatic lipogenesis. CONCLUSION: Our results support autophagy as one of the therapeutic strategies to reduce steatosis and hepatic damage. We found that androsin treatment significantly ameliorated hepatic steatosis, serum lipid levels, and hepatic injury in ApoE-/- induced by HFrD. Androsin administration mitigated lipogenesis by inhibiting SREBP1c/FASN pathway and activating autophagy through AMPKα/PI3K/Beclin1/LC3 pathway.


Assuntos
Autofagia , Glucosídeos Iridoides , Lipogênese , Hepatopatia Gordurosa não Alcoólica , Animais , Hepatopatia Gordurosa não Alcoólica/tratamento farmacológico , Lipogênese/efeitos dos fármacos , Autofagia/efeitos dos fármacos , Masculino , Camundongos , Glucosídeos Iridoides/farmacologia , Cinamatos/farmacologia , Fígado/efeitos dos fármacos , Picrorhiza/química , Células Hep G2 , Camundongos Endogâmicos C57BL , Humanos
9.
Nanoscale Adv ; 5(10): 2756-2766, 2023 May 16.
Artigo em Inglês | MEDLINE | ID: mdl-37205289

RESUMO

Thermal transport and exciton dynamics of semiconducting transition metal dichalcogenides (TMDCs) play an immense role in next-generation electronic, photonic, and thermoelectric devices. In this work, we synthesize distinct morphologies (snow-like and hexagonal) of a trilayer MoSe2 film over the SiO2/Si substrate via the chemical vapor deposition (CVD) method and investigated their morphological dependent exciton dynamics and thermal transport behaviour for the first time to the best of our knowledge. Firstly, we studied the role of spin-orbit and interlayer couplings both theoretically as well as experimentally via first-principles density functional theory and photoluminescence study, respectively. Further, we demonstrate morphological dependent thermal sensitive exciton response at low temperatures (93-300 K), showing more dominant defect-bound excitons (EL) in snow-like MoSe2 compared to hexagonal morphology. We also examined the morphological-dependent phonon confinement and thermal transport behaviour using the optothermal Raman spectroscopy technique. To provide insights into the nonlinear temperature-dependent phonon anharmonicity, a semi-quantitative model comprising volume and temperature effects was used, divulging the dominance of three-phonon (four-phonon) scattering processes for thermal transport in hexagonal (snow-like) MoSe2. The morphological impact on thermal conductivity (ks) of MoSe2 has also been examined here by performing the optothermal Raman spectroscopy, showing ks ∼ 36 ± 6 W m-1 K-1 for snow-like and ∼41 ± 7 W m-1 K-1 for hexagonal MoSe2. Our research will contribute to the understanding of thermal transport behaviour in different morphologies of semiconducting MoSe2, finding suitability for next-generation optoelectronic devices.

10.
Am J Emerg Med ; 30(8): 1569-73, 2012 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-22030180

RESUMO

OBJECTIVE: The objective was to compare bedside ultrasound (US) to clinical examination for the detection of abscess. METHODS: This is a 24-month prospective, observational emergency department (ED) study. Adults with suspected nondraining abscess with planned incision and drainage (I&D) are included in the study. Exclusion criteria are spontaneous drainage and perineal, perirectal, or intraoral location. Before I&D, a second ED physician conducts an US and records the presence or absence of findings suggestive of abscess. A positive I&D of the suspected abscess is the criterion standard. The treating practitioner is blinded to the US results. Ultrasound is performed by novice ED physicians. The findings of the US, the prediction of pus from the clinician and the ultrasonographer in 3 strata (low, indeterminate, definite), and the results of the I&D (pus/no pus) are recorded onto data sheets. Measures of association are reported and Fisher's Exact test is used. RESULTS: Forty patients were enrolled. The sensitivity of novice sonographers to predict a positive I&D with US was 0.97 (0.83-1.00), the specificity was 0.67 (0.24-0.94), the positive likelihood ratio was 2.90, the negative likelihood ratio was 0.04, and the area under the receiver operating characteristic curve was 0.85 (0.66-1.00). Clinical examination yielded a sensitivity of 0.76 (0.58-0.89), specificity of 0.83 (0.36-0.99), positive likelihood ratio of 4.50, negative likelihood ratio of 0.29, and area under the receiver operating characteristic curve of 0.75 (0.50-1.00). CONCLUSION: Novice ED sonographers can identify abscesses with only minimal US training. Identification of abscess on US may change management of cutaneous abscesses.


Assuntos
Abscesso/diagnóstico por imagem , Serviço Hospitalar de Emergência , Sistemas Automatizados de Assistência Junto ao Leito , Infecções dos Tecidos Moles/diagnóstico por imagem , Abscesso/diagnóstico , Adulto , Humanos , Exame Físico , Médicos , Estudos Prospectivos , Sensibilidade e Especificidade , Infecções dos Tecidos Moles/diagnóstico , Ultrassonografia
11.
Nano Lett ; 11(5): 2004-7, 2011 May 11.
Artigo em Inglês | MEDLINE | ID: mdl-21524100

RESUMO

A scanning tunneling microscope was used to study the ionization of single Mn acceptors in GaAs(110). The ionization state switches when the GaAs valence band is bent across a Mn acceptor level. This produces a ringlike feature in STM images, whose diameter depends on the tunneling conditions and distance to charged arsenic vacancies. By varying the latter, we could tune the ionization switching, as well as quantify the contributions from tip- and vacancy-induced band bending.

12.
Annu Int Conf IEEE Eng Med Biol Soc ; 2022: 1747-1752, 2022 07.
Artigo em Inglês | MEDLINE | ID: mdl-36086009

RESUMO

Hemorrhage is the leading cause of preventable death from trauma. Traditionally, vital signs have been used to detect blood loss and possible hemorrhagic shock. However, vital signs are not sensitive for early detection because of physiological mechanisms that compensate for blood loss. As an alternative, machine learning algorithms that operate on an arterial blood pressure (ABP) waveform acquired via photoplethysmography have been shown to provide an effective early indicator. However, these machine learning approaches lack physiological interpretability. In this paper, we evaluate the importance of nine ABP-derived features that provide physiological insight, using a database of 40 human subjects from a lower-body negative pressure model of progressive central hypovolemia. One feature was found to be considerably more important than any other. That feature, the half-rise to dicrotic notch (HRDN), measures an approximate time delay between the ABP ejected and reflected wave components. This delay is an indication of compensatory mechanisms such as reduced arterial compliance and vasoconstriction. For a scale of 0% to 100%, with 100% representing normovolemia and 0% representing decompensation, linear regression of the HRDN feature results in root-mean-squared error of 16.9%, R2 of 0.72, and an area under the receiver operating curve for detecting decompensation of 0.88. These results are comparable to previously reported results from the more complex black box machine learning models. Clinical Relevance- A single physiologically interpretable feature measured from an arterial blood pressure waveform is shown to be effective in monitoring for blood loss and impending hemorrhagic shock based on data from a human lower-body negative pressure model of progressive central hypolemia.


Assuntos
Doenças Cardiovasculares , Choque Hemorrágico , Pressão Sanguínea/fisiologia , Doenças Cardiovasculares/complicações , Hemorragia , Humanos , Hipovolemia/diagnóstico , Pressão Negativa da Região Corporal Inferior/efeitos adversos , Choque Hemorrágico/complicações , Choque Hemorrágico/diagnóstico
13.
Biosensors (Basel) ; 12(12)2022 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-36551134

RESUMO

Hemorrhage is the leading cause of preventable death from trauma. Accurate monitoring of hemorrhage and resuscitation can significantly reduce mortality and morbidity but remains a challenge due to the low sensitivity of traditional vital signs in detecting blood loss and possible hemorrhagic shock. Vital signs are not reliable early indicators because of physiological mechanisms that compensate for blood loss and thus do not provide an accurate assessment of volume status. As an alternative, machine learning (ML) algorithms that operate on an arterial blood pressure (ABP) waveform have been shown to provide an effective early indicator. However, these ML approaches lack physiological interpretability. In this paper, we evaluate and compare the performance of ML models trained on nine ABP-derived features that provide physiological insight, using a database of 13 human subjects from a lower-body negative pressure (LBNP) model of progressive central hypovolemia and subsequent progressive restoration to normovolemia (i.e., simulated hemorrhage and whole blood resuscitation). Data were acquired at multiple repressurization rates for each subject to simulate varying resuscitation rates, resulting in 52 total LBNP collections. This work is the first to use a single ABP-based algorithm to monitor both simulated hemorrhage and resuscitation. A gradient-boosted regression tree model trained on only the half-rise to dicrotic notch (HRDN) feature achieved a root-mean-square error (RMSE) of 13%, an R2 of 0.82, and area under the receiver operating characteristic curve of 0.97 for detecting decompensation. This single-feature model's performance compares favorably to previously reported results from more-complex black box machine learning models. This model further provides physiological insight because HRDN represents an approximate measure of the delay between the ABP ejected and reflected wave and therefore is an indication of cardiac and peripheral vascular mechanisms that contribute to the compensatory response to blood loss and replacement.


Assuntos
Volume Sanguíneo , Hemorragia , Humanos , Pressão Sanguínea/fisiologia , Volume Sanguíneo/fisiologia , Hemorragia/complicações , Hemorragia/diagnóstico , Hipovolemia/diagnóstico , Hipovolemia/etiologia , Sinais Vitais
14.
Adv Mater ; 34(21): e2201387, 2022 May.
Artigo em Inglês | MEDLINE | ID: mdl-35355349

RESUMO

Monolayer hexagonal boron nitride (hBN) has been widely considered a fundamental building block for 2D heterostructures and devices. However, the controlled and scalable synthesis of hBN and its 2D heterostructures has remained a daunting challenge. Here, an hBN/graphene (hBN/G) interface-mediated growth process for the controlled synthesis of high-quality monolayer hBN is proposed and further demonstrated. It is discovered that the in-plane hBN/G interface can be precisely controlled, enabling the scalable epitaxy of unidirectional monolayer hBN on graphene, which exhibits a uniform moiré superlattice consistent with single-domain hBN, aligned to the underlying graphene lattice. Furthermore, it is identified that the deep-ultraviolet emission at 6.12 eV stems from the 1s-exciton state of monolayer hBN with a giant renormalized direct bandgap on graphene. This work provides a viable path for the controlled synthesis of ultraclean, wafer-scale, atomically ordered 2D quantum materials, as well as the fabrication of 2D quantum electronic and optoelectronic devices.

15.
Nano Lett ; 10(10): 4175-80, 2010 Oct 13.
Artigo em Inglês | MEDLINE | ID: mdl-20831233

RESUMO

Single tetracyanoethyelene (TCNE) molecules on Cu(111) are reversibly switched among five states by applying voltage pulses with the tip of a scanning tunneling microscope. A pronounced Kondo resonance in tunneling spectroscopy indicates that one of the states is magnetic. Side bands of the Kondo resonance appear at energies which correspond to inter- and intramolecular vibrational modes. Density functional theory suggests that molecular deformation changes the occupancy in TCNE's molecular orbitals, thus producing the magnetic state.

16.
Ticks Tick Borne Dis ; 12(6): 101791, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34329928

RESUMO

The multi-host tick, Hyalomma anatolicum is a widely distributed vector of many pathogens of veterinary and public health importance. Ivermectin (IVM), as an alternative to control pyrethroid-resistant ticks, has been used extensively for the past 4-6 years in tropical and sub-tropical countries including India resulting in declining tick control efficacy. The present study used adult immersion test (AIT) to examine the resistance status of H. anatolicum collected from three districts in the Indian state of Gujarat against ivermectin. Probit analysis was used for calculation of concentration-mortality regressions; concentrations required for 50% mortality (LC50) and 95% mortality (LC95), along with confidence intervals; slope of mortality; % inhibition of oviposition; and discriminating concentration (DC). The calculated LC50 and LC95 estimates were utilized to determine resistance ratios (RR50, RR95) and the resistance levels (RL) of the field ticks compared to the susceptible population. The DC (2 x LC95) for IVM was calculated as 84.48 ppm, using susceptible H. anatolicum ticks (KHD). Lower estimates of the coefficient of non-determination (1-R2) for AIT ranged from 0.06 to 0.27, and the range of RR50 and RR95 values against IVM was estimated to be from 1.43 to 52.06 and 1.14 to 71.99, respectively, which indicated a varying degree of resistance among the field tick populations. Based on RR50 values, tick populations from Danta and Palanpur showed resistance level IV and II, respectively. Another four populations (Vadgam, Kankrej, Saraswati and Sidhpur) were classified as having level I resistance status against IVM. To our knowledge, this is the first report of ivermectin resistance in H. anatolicum from Gujarat, India.


Assuntos
Acaricidas/farmacologia , Resistência a Medicamentos , Ivermectina/farmacologia , Ixodidae/efeitos dos fármacos , Animais , Feminino , Índia , Mortalidade
17.
Science ; 374(6574): 1484-1487, 2021 Dec 17.
Artigo em Inglês | MEDLINE | ID: mdl-34914516

RESUMO

Topological spin textures in chiral magnets such as manganese germanide (MnGe) are of fundamental interest and may enable magnetic storage and computing technologies. Our spin-polarized scanning tunneling microscopy images of MnGe thin films reveal a variety of textures that are correlated to the atomic-scale structure. Our images indicate helical stripe domains, in contrast to bulk, and associated helimagnetic domain walls. In combination with micromagnetic modeling, we can deduce the three-dimensional (3D) orientation of the helical wave vectors, and we find that three helical domains can meet in two distinct ways to produce either a "target-like" or a "π-like" topological spin texture. The target-like texture can be reversibly manipulated through either current/voltage pulsing or applied magnetic field, which represents a promising step toward future applications.

18.
Biosensors (Basel) ; 11(12)2021 Dec 18.
Artigo em Inglês | MEDLINE | ID: mdl-34940279

RESUMO

Hemorrhage is a leading cause of trauma death, particularly in prehospital environments when evacuation is delayed. Obtaining central vascular access to a deep artery or vein is important for administration of emergency drugs and analgesics, and rapid replacement of blood volume, as well as invasive sensing and emerging life-saving interventions. However, central access is normally performed by highly experienced critical care physicians in a hospital setting. We developed a handheld AI-enabled interventional device, AI-GUIDE (Artificial Intelligence Guided Ultrasound Interventional Device), capable of directing users with no ultrasound or interventional expertise to catheterize a deep blood vessel, with an initial focus on the femoral vein. AI-GUIDE integrates with widely available commercial portable ultrasound systems and guides a user in ultrasound probe localization, venous puncture-point localization, and needle insertion. The system performs vascular puncture robotically and incorporates a preloaded guidewire to facilitate the Seldinger technique of catheter insertion. Results from tissue-mimicking phantom and porcine studies under normotensive and hypotensive conditions provide evidence of the technique's robustness, with key performance metrics in a live porcine model including: a mean time to acquire femoral vein insertion point of 53 ± 36 s (5 users with varying experience, in 20 trials), a total time to insert catheter of 80 ± 30 s (1 user, in 6 trials), and a mean number of 1.1 (normotensive, 39 trials) and 1.3 (hypotensive, 55 trials) needle insertion attempts (1 user). These performance metrics in a porcine model are consistent with those for experienced medical providers performing central vascular access on humans in a hospital.


Assuntos
Cateterismo Venoso Central , Procedimentos Cirúrgicos Robóticos , Ultrassonografia de Intervenção , Animais , Inteligência Artificial , Veia Femoral/diagnóstico por imagem , Humanos , Suínos
19.
J Phys Condens Matter ; 33(27)2021 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-33878736

RESUMO

We report scanning tunneling microscopy (STM) studies of individual adatoms deposited on an InSb(110) surface. The adatoms can be reproducibly dropped off from the STM tip by voltage pulses, and impact tunneling into the surface by up to ∼100×. The spatial extent and magnitude of the tunneling effect are widely tunable by imaging conditions such as bias voltage, set current and photoillumination. We attribute the effect to occupation of a (+/0) charge transition level, and switching of the associated adatom-induced band bending. The effect in STM topographic images is well reproduced by transport modeling of filling and emptying rates as a function of the tip position. STM atomic contrast and tunneling spectra are in good agreement with density functional theory calculations for In adatoms. The adatom ionization effect can extend to distances greater than 50 nm away, which we attribute to the low concentration and low binding energy of the residual donors in the undoped InSb crystal. These studies demonstrate how individual atoms can be used to sensitively control current flow in nanoscale devices.

20.
J Neurosci ; 29(48): 15100-3, 2009 Dec 02.
Artigo em Inglês | MEDLINE | ID: mdl-19955361

RESUMO

A(2A) receptors are a major class of G-protein-coupled receptors for adenosine. Highly expressed in the striatum, on the projection neurons giving rise to the striatopallidal or "indirect" pathway, they have been implicated in sleep, addiction, and other processes, yet their role in the control of striatal circuits and behavior remains unclear. Using established assays from the instrumental learning paradigm, we showed that mice with striatum-specific deletion of A(2A) receptors were selectively impaired in habit formation. After training that generated habitual lever pressing in wild-type controls, the performance of striatum-specific A(2A) knock-out mice remained goal directed, being highly sensitive to outcome devaluation and reversal of the action-outcome contingency. These data demonstrate a critical role for A(2A) receptors on striatopallidal medium spiny projection neurons in shaping behavior and decision making, providing the first instance of a selective alteration in instrumental learning after striatum-specific genetic manipulations.


Assuntos
Corpo Estriado/metabolismo , Deleção de Genes , Hábitos , Deficiências da Aprendizagem/genética , Receptor A2A de Adenosina/deficiência , Receptor A2A de Adenosina/genética , Análise de Variância , Animais , Comportamento Animal , Condicionamento Operante/fisiologia , Extinção Psicológica/fisiologia , Proteínas de Homeodomínio/genética , Camundongos , Camundongos Transgênicos , Esquema de Reforço
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