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1.
Phys Rev Lett ; 132(16): 162501, 2024 Apr 19.
Artículo en Inglés | MEDLINE | ID: mdl-38701469

RESUMEN

The electromagnetic form factors of the proton and neutron encode information on the spatial structure of their charge and magnetization distributions. While measurements of the proton are relatively straightforward, the lack of a free neutron target makes measurements of the neutron's electromagnetic structure more challenging and more sensitive to experimental or model-dependent uncertainties. Various experiments have attempted to extract the neutron form factors from scattering from the neutron in deuterium, with different techniques providing different, and sometimes large, systematic uncertainties. We present results from a novel measurement of the neutron magnetic form factor using quasielastic scattering from the mirror nuclei ^{3}H and ^{3}He, where the nuclear effects are larger than for deuterium but expected to largely cancel in the cross-section ratios. We extracted values of the neutron magnetic form factor for low-to-modest momentum transfer, 0.6

2.
Nature ; 609(7925): 41-45, 2022 09.
Artículo en Inglés | MEDLINE | ID: mdl-36045235

RESUMEN

When protons and neutrons (nucleons) are bound into atomic nuclei, they are close enough to feel significant attraction, or repulsion, from the strong, short-distance part of the nucleon-nucleon interaction. These strong interactions lead to hard collisions between nucleons, generating pairs of highly energetic nucleons referred to as short-range correlations (SRCs). SRCs are an important but relatively poorly understood part of nuclear structure1-3, and mapping out the strength and the isospin structure (neutron-proton (np) versus proton-proton (pp) pairs) of these virtual excitations is thus critical input for modelling a range of nuclear, particle and astrophysics measurements3-5. Two-nucleon knockout or 'triple coincidence' reactions have been used to measure the relative contribution of np-SRCs and pp-SRCs by knocking out a proton from the SRC and detecting its partner nucleon (proton or neutron). These measurements6-8 have shown that SRCs are almost exclusively np pairs, but they had limited statistics and required large model-dependent final-state interaction corrections. Here we report on measurements using inclusive scattering from the mirror nuclei hydrogen-3 and helium-3 to extract the np/pp ratio of SRCs in systems with a mass number of three. We obtain a measure of the np/pp SRC ratio that is an order of magnitude more precise than previous experiments, and find a marked deviation from the near-total np dominance observed in heavy nuclei. This result implies an unexpected structure in the high-momentum wavefunction for hydrogen-3 and helium-3. Understanding these results will improve our understanding of the short-range part of the nucleon-nucleon interaction.

3.
Phys Rev Lett ; 128(13): 132003, 2022 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-35426713

RESUMEN

The ratio of the nucleon F_{2} structure functions, F_{2}^{n}/F_{2}^{p}, is determined by the MARATHON experiment from measurements of deep inelastic scattering of electrons from ^{3}H and ^{3}He nuclei. The experiment was performed in the Hall A Facility of Jefferson Lab using two high-resolution spectrometers for electron detection, and a cryogenic target system which included a low-activity tritium cell. The data analysis used a novel technique exploiting the mirror symmetry of the two nuclei, which essentially eliminates many theoretical uncertainties in the extraction of the ratio. The results, which cover the Bjorken scaling variable range 0.19

4.
Phys Rev Lett ; 126(8): 082301, 2021 Feb 26.
Artículo en Inglés | MEDLINE | ID: mdl-33709760

RESUMEN

Quasielastic ^{12}C(e,e^{'}p) scattering was measured at spacelike 4-momentum transfer squared Q^{2}=8, 9.4, 11.4, and 14.2 (GeV/c)^{2}, the highest ever achieved to date. Nuclear transparency for this reaction was extracted by comparing the measured yield to that expected from a plane-wave impulse approximation calculation without any final state interactions. The measured transparency was consistent with no Q^{2} dependence, up to proton momenta of 8.5 GeV/c, ruling out the quantum chromodynamics effect of color transparency at the measured Q^{2} scales in exclusive (e,e^{'}p) reactions. These results impose strict constraints on models of color transparency for protons.

5.
Phys Rev Lett ; 124(21): 212501, 2020 May 29.
Artículo en Inglés | MEDLINE | ID: mdl-32530643

RESUMEN

We report the first measurement of the (e,e^{'}p) three-body breakup reaction cross sections in helium-3 (^{3}He) and tritium (^{3}H) at large momentum transfer [⟨Q^{2}⟩≈1.9 (GeV/c)^{2}] and x_{B}>1 kinematics, where the cross section should be sensitive to quasielastic (QE) scattering from single nucleons. The data cover missing momenta 40≤p_{miss}≤500 MeV/c that, in the QE limit with no rescattering, equals the initial momentum of the probed nucleon. The measured cross sections are compared with state-of-the-art ab initio calculations. Overall good agreement, within ±20%, is observed between data and calculations for the full p_{miss} range for ^{3}H and for 100≤p_{miss}≤350 MeV/c for ^{3}He. Including the effects of rescattering of the outgoing nucleon improves agreement with the data at p_{miss}>250 MeV/c and suggests contributions from charge-exchange (SCX) rescattering. The isoscalar sum of ^{3}He plus ^{3}H, which is largely insensitive to SCX, is described by calculations to within the accuracy of the data over the entire p_{miss} range. This validates current models of the ground state of the three-nucleon system up to very high initial nucleon momenta of 500 MeV/c.

6.
Phys Rev Lett ; 125(26): 262501, 2020 Dec 31.
Artículo en Inglés | MEDLINE | ID: mdl-33449750

RESUMEN

We measure ^{2}H(e,e^{'}p)n cross sections at 4-momentum transfers of Q^{2}=4.5±0.5 (GeV/c)^{2} over a range of neutron recoil momenta p_{r}, reaching up to ∼1.0 GeV/c. We obtain data at fixed neutron recoil angles θ_{nq}=35°, 45°, and 75° with respect to the 3-momentum transfer q[over →]. The new data agree well with previous data, which reached p_{r}∼500 MeV/c. At θ_{nq}=35° and 45°, final state interactions, meson exchange currents, and isobar currents are suppressed and the plane wave impulse approximation provides the dominant cross section contribution. We compare the new data to recent theoretical calculations, where we observe a significant discrepancy for recoil momenta p_{r}>700 MeV/c.

7.
Chaos ; 29(7): 073120, 2019 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-31370422

RESUMEN

Perhaps because of the elegance of the central limit theorem, it is often assumed that distributions in nature will approach singly-peaked, unimodal shapes reminiscent of the Gaussian normal distribution. However, many systems behave differently, with variables following apparently bimodal or multimodal distributions. Here, we argue that multimodality may emerge naturally as a result of repulsive or inhibitory coupling dynamics, and we show rigorously how it emerges for a broad class of coupling functions in variants of the paradigmatic Kuramoto model.

8.
Curr Oncol ; 23(2): S8-S14, 2016 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-27022315

RESUMEN

Cannabis species have been used as medicine for thousands of years; only since the 1940s has the plant not been widely available for medical use. However, an increasing number of jurisdictions are making it possible for patients to obtain the botanical for medicinal use. For the cancer patient, cannabis has a number of potential benefits, especially in the management of symptoms. Cannabis is useful in combatting anorexia, chemotherapy-induced nausea and vomiting, pain, insomnia, and depression. Cannabis might be less potent than other available antiemetics, but for some patients, it is the only agent that works, and it is the only antiemetic that also increases appetite. Inhaled cannabis is more effective than placebo in ameliorating peripheral neuropathy in a number of conditions, and it could prove useful in chemotherapy-induced neuropathy. A pharmacokinetic interaction study of vaporized cannabis in patients with chronic pain on stable doses of sustained-release opioids demonstrated no clinically significant change in plasma opiates, while suggesting the possibility of synergistic analgesia. Aside from symptom management, an increasing body of in vitro and animal-model studies supports a possible direct anticancer effect of cannabinoids by way of a number of different mechanisms involving apoptosis, angiogenesis, and inhibition of metastasis. Despite an absence of clinical trials, abundant anecdotal reports that describe patients having remarkable responses to cannabis as an anticancer agent, especially when taken as a high-potency orally ingested concentrate, are circulating. Human studies should be conducted to address critical questions related to the foregoing effects.

9.
Support Care Cancer ; 24(7): 3085-93, 2016 07.
Artículo en Inglés | MEDLINE | ID: mdl-26894485

RESUMEN

PURPOSE: Bone pain is a common side effect of pegfilgrastim and can interfere with quality of life and treatment adherence. This study investigated the impact of antihistamine prophylaxis on pegfilgrastim-induced bone pain. METHODS: This is a two-stage enrichment trial design. Patients receiving an initial dose of pegfilgrastim after chemotherapy were enrolled into the observation (OBS) stage. Those who developed significant back or leg bone pain (SP) were enrolled into the treatment (TRT) stage and randomized to daily loratadine 10 mg or placebo for 7 days. SP was defined by Brief Pain Inventory as back or leg pain score ≥5 and a 2-point increase after pegfilgrastim. The primary end point of TRT was reduction of worst back or leg bone pain with loratadine, defined as a 2-point decrease after treatment compared to OBS. RESULTS: Two hundred thirteen patients were included in the final analysis. Incidence of SP was 30.5 %. The SP subset had a worse overall Functional Assessment of Cancer Therapy-Bone Pain score (33.9 vs. 51.7, p < 0.001) and a higher mean white blood cell count (15.4 vs. 8.4 K/cm(3), p = 0.013) following pegfilgrastim than those without SP. Forty-six patients were randomized in the TRT. Benefit was 77.3 % with loratadine and 62.5 % with placebo (p = 0.35). Baseline NSAID use was documented in four patients (18.2 %) in loratadine arm and two patients (8.3 %) in placebo arm, with baseline non-NSAID use documented in five (22.7 %) and six (25 %) patients, respectively. Eight additional patients used NSAIDS by day 8 compared to day 1 (six in the loratadine and two in the placebo arm). A total of six additional patients used non-NSAIDS by day 8 compared to day 1 (four in the loratadine and two in the placebo arm). CONCLUSIONS: Administration of prophylactic loratadine does not decrease the incidence of severe bone pain or improve quality of life in a high-risk patient population. ClinicalTrials.gov identifier: NCT01311336.


Asunto(s)
Enfermedades Óseas/prevención & control , Factor Estimulante de Colonias de Granulocitos/efectos adversos , Antagonistas de los Receptores Histamínicos H1 no Sedantes/uso terapéutico , Loratadina/uso terapéutico , Manejo del Dolor/métodos , Adulto , Anciano , Anciano de 80 o más Años , Enfermedades Óseas/inducido químicamente , Femenino , Filgrastim , Humanos , Masculino , Persona de Mediana Edad , Polietilenglicoles , Calidad de Vida , Proteínas Recombinantes/efectos adversos , Adulto Joven
10.
Appl Radiat Isot ; 110: 193-199, 2016 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-26829618

RESUMEN

Hydrophobic adsorbents such as C18 and C30 were coated with PEG and subsequently used for the separation of Mo/Tc. The most effective resin for adsorbing PEG was the C18-U resin, which demonstrated a coating capacity of 97.6±2.8mg PEG per g of resin. The ability to adsorb pertechnetate was proportional to the amount of PEG coated on the hydrophobic resin. The [(99m)Tc]pertechnetate recovery during the separation of cyclotron produced (99m)Tc from (100)Mo was 91.8±0.3% (n=2). The resultant product met relevant USP monograph specifications.


Asunto(s)
Molibdeno/aislamiento & purificación , Pertecnetato de Sodio Tc 99m/aislamiento & purificación , Adsorción , Ciclotrones , Humanos , Interacciones Hidrofóbicas e Hidrofílicas , Isótopos/aislamiento & purificación , Polietilenglicoles , Radioisótopos/aislamiento & purificación , Radiofármacos/aislamiento & purificación , Resinas Sintéticas
11.
Ground Water ; 54(1): 66-73, 2016 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-25628100

RESUMEN

Regional finite-difference models often have cell sizes that are too large to sufficiently model well-stream interactions. Here, a steady-state hybrid model is applied whereby the upper layer or layers of a coarse MODFLOW model are replaced by the analytic element model GFLOW, which represents surface waters and wells as line and point sinks. The two models are coupled by transferring cell-by-cell leakage obtained from the original MODFLOW model to the bottom of the GFLOW model. A real-world test of the hybrid model approach is applied on a subdomain of an existing model of the Lake Michigan Basin. The original (coarse) MODFLOW model consists of six layers, the top four of which are aggregated into GFLOW as a single layer, while the bottom two layers remain part of MODFLOW in the hybrid model. The hybrid model and a refined "benchmark" MODFLOW model simulate similar baseflows. The hybrid and benchmark models also simulate similar baseflow reductions due to nearby pumping when the well is located within the layers represented by GFLOW. However, the benchmark model requires refinement of the model grid in the local area of interest, while the hybrid approach uses a gridless top layer and is thus unaffected by grid discretization errors. The hybrid approach is well suited to facilitate cost-effective retrofitting of existing coarse grid MODFLOW models commonly used for regional studies because it leverages the strengths of both finite-difference and analytic element methods for predictions in mildly heterogeneous systems that can be simulated with steady-state conditions.


Asunto(s)
Simulación por Computador , Agua Subterránea , Movimientos del Agua , Great Lakes Region , Ríos , Pozos de Agua
12.
Clin Pharmacol Ther ; 97(6): 575-86, 2015 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-25777363

RESUMEN

Cannabis has been used in medicine for thousands of years prior to achieving its current illicit substance status. Cannabinoids, the active components of Cannabis sativa, mimic the effects of the endogenous cannabinoids (endocannabinoids), activating specific cannabinoid receptors, particularly CB1 found predominantly in the central nervous system and CB2 found predominantly in cells involved with immune function. Delta-9-tetrahydrocannabinol, the main bioactive cannabinoid in the plant, has been available as a prescription medication approved for treatment of cancer chemotherapy-induced nausea and vomiting and anorexia associated with the AIDS wasting syndrome. Cannabinoids may be of benefit in the treatment of cancer-related pain, possibly synergistic with opioid analgesics. Cannabinoids have been shown to be of benefit in the treatment of HIV-related peripheral neuropathy, suggesting that they may be worthy of study in patients with other neuropathic symptoms. Cannabinoids have a favorable drug safety profile, but their medical use is predominantly limited by their psychoactive effects and their limited bioavailability.


Asunto(s)
Cannabinoides/uso terapéutico , Marihuana Medicinal/uso terapéutico , Neoplasias/tratamiento farmacológico , Analgesia , Analgésicos Opioides/farmacología , Animales , Apetito/efectos de los fármacos , Cannabinoides/efectos adversos , Cannabinoides/farmacología , Interacciones Farmacológicas , Humanos , Neoplasias/fisiopatología , Dolor Intratable/tratamiento farmacológico , Vómitos/tratamiento farmacológico
13.
Minerva Med ; 106(1): 45-52, 2015 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-25283259

RESUMEN

Extracorporeal membrane oxygenation (ECMO) technology has undergone significant advancement in the last several years. These changes have led to more compact circuits that are increasingly efficient at gas exchange while decreasing the complication rates often associated with its use. The ability to remove carbon dioxide at relatively low flows has broadened the application of ECMO in the management of respiratory failure. As this technology continues to evolve, there is great promise of a portable lung replacement therapy, an artificial lung, which would have far-reaching implications in the approach to both acute and chronic respiratory failure.


Asunto(s)
Oxigenación por Membrana Extracorpórea , Insuficiencia Respiratoria/terapia , Órganos Artificiales , Oxigenación por Membrana Extracorpórea/tendencias , Predicción , Humanos , Pulmón , Índice de Severidad de la Enfermedad , Terapias en Investigación
14.
Perfusion ; 30(5): 407-9, 2015 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-25313096

RESUMEN

Venovenous extracorporeal membrane oxygenation (ECMO) is used for patients with severe, potentially reversible, respiratory failure unresponsive to conventional management. It is relatively contraindicated in patients with traumatic brain injury (TBI) due to bleeding complications and use of anticoagulation. We report two cases of TBI patients treated with ECMO.


Asunto(s)
Anticoagulantes/administración & dosificación , Hemorragia Encefálica Traumática/terapia , Oxigenación por Membrana Extracorpórea , Adolescente , Adulto , Hemorragia Encefálica Traumática/diagnóstico por imagen , Hemorragia Encefálica Traumática/fisiopatología , Humanos , Masculino , Radiografía
15.
Perfusion ; 29(1): 26-8, 2014 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-23842616

RESUMEN

Extracorporeal carbon dioxide removal (ECCO2R) may be indicated for refractory status asthmaticus when severe dynamic hyperinflation or life-threatening respiratory acidosis persists despite optimal medical and ventilator management. Most prior reports describe the application of ECCO2R to rapid-onset asthma exacerbation, requiring a short duration of extracorporeal support. We report two patients with refractory status asthmaticus managed with ECCO2R, emphasizing the use of modern extracorporeal technology, cannulation technique and management protocols, which may improve the risk-to-benefit profile of this strategy. This report highlights the challenges in managing patients with distinct asthma exacerbation phenotypes. The potential need for prolonged device support may alter provider expectations and offers a new perspective of the role of ECCO2R for status asthmaticus.


Asunto(s)
Dióxido de Carbono/metabolismo , Circulación Extracorporea/métodos , Oxigenación por Membrana Extracorpórea/métodos , Estado Asmático/terapia , Humanos , Masculino , Persona de Mediana Edad , Fenotipo
16.
Perfusion ; 29(1): 53-6, 2014 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-23863493

RESUMEN

A 50-year-old man was admitted to the intensive care unit with respiratory failure and shock after suffering a massive overdose of amlodipine, lisinopril and hydrochlorothiazide. Despite mechanical ventilation, vasopressors, calcium gluconate, hyperinsulinemia-euglycemia therapy, methylene blue and intravenous fat emulsion, the patient's respiratory and hemodynamic status deteriorated. Venoarterial extracorporeal membrane oxygenation (ECMO) was initiated to provide cardiopulmonary support in the setting of profound respiratory failure and refractory shock. The patient was placed on ECMO 19 hours after arrival to the hospital, after which vasopressor and ventilatory requirements decreased significantly. The patient was decannulated from ECMO after 8 days and was discharged home after a 56-day hospitalization. Early institution of ECMO should be considered for the management of respiratory failure and refractory shock in the setting of calcium channel blocker overdose when medical therapies are insufficient.


Asunto(s)
Amlodipino/envenenamiento , Oxigenación por Membrana Extracorpórea/métodos , Hidroclorotiazida/envenenamiento , Lisinopril/envenenamiento , Humanos , Masculino , Persona de Mediana Edad , Respiración Artificial , Insuficiencia Respiratoria/terapia , Resultado del Tratamiento
17.
J Matern Fetal Neonatal Med ; 25(11): 2467-9, 2012 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-22765762

RESUMEN

OBJECTIVE: We examined the yield and quality of genomic deoxyribonucleic acid (DNA) extracted from various postmortem fetal tissues. METHODS: Fetal tissues were collected at the time of autopsy, and DNA was subsequently extracted. The yield and DNA quality was assessed using ultraviolet spectrometry and agarose gel electrophoresis. We used polymerase chain reaction (PCR) to assess the DNA extracted for genomic testing. RESULTS: The median (range) gestation of the fetuses was 22 (16-41) weeks and the postmortem interval was 5.5 (2-10) days. Non-degraded genomic DNA was successfully extracted from all fetal tissues. Liver tissue had the lowest quality and muscle the highest quality. DNA yield or purity was not influenced by the postmortem interval. CONCLUSION: High quality genomic DNA can be extracted from fetal muscle, despite postmortem intervals of several days.


Asunto(s)
Autopsia , ADN/aislamiento & purificación , Feto/química , Pruebas Genéticas/normas , Eficiencia , Feto/metabolismo , Genoma Humano , Edad Gestacional , Corazón/embriología , Humanos , Riñón/química , Riñón/embriología , Riñón/metabolismo , Riñón/patología , Hígado/química , Hígado/embriología , Hígado/metabolismo , Hígado/patología , Músculos/química , Músculos/embriología , Músculos/metabolismo , Músculos/patología , Miocardio/química , Miocardio/metabolismo , Miocardio/patología , Reacción en Cadena de la Polimerasa/métodos , Control de Calidad
18.
Appl Radiat Isot ; 70(8): 1685-90, 2012 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-22750197

RESUMEN

There is growing interest in the large scale cyclotron production of (99m)Tc via the (100)Mo(p,2n)(99m)Tc reaction. While the use and recycling of cyclotron-irradiated enriched molybdenum targets has been reported previously in the context of (94m)Tc production, to the best of our knowledge, previous recycling studies have been limited to the use of oxide targets. To facilitate reuse of high-power enriched (100)Mo targets, this work presents and evaluates a strategy for recycling of enriched metallic molybdenum. For the irradiated (100)Mo targets in this study, an overall metal to metal recovery of 87% is reported. Evaluation of "new" and "recycled" (100)Mo revealed no changes in the molybdenum isotopic composition (as measured via ICP-MS). For similar irradiation conditions of "new" and "recycled" (100)Mo, (i.e. target thicknesses, irradiation time, and energy), comparable levels of (94g)Tc, (95g)Tc, and (96g)Tc contaminants were observed. Comparable QC specifications (i.e. aluminum ion concentration, pH, and radiochemical purity) were also reported. We finally note that [(99m)Tc]-MDP images obtained by comparing MDP labelled with generator-based (99m)Tc vs. (99m)Tc obtained following the irradiation of recycled (100)Mo demonstrated comparable biodistribution. With the goal of producing large quantities of (99m)Tc, the proposed methodology demonstrates that efficient recycling of enriched metallic (100)Mo targets is feasible and effective.

19.
Clin Pharmacol Ther ; 90(6): 844-51, 2011 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-22048225

RESUMEN

Cannabinoids and opioids share several pharmacologic properties and may act synergistically. The potential pharmacokinetics and the safety of the combination in humans are unknown. We therefore undertook a study to answer these questions. Twenty-one individuals with chronic pain, on a regimen of twice-daily doses of sustained-release morphine or oxycodone were enrolled in the study and admitted for a 5-day inpatient stay. Participants were asked to inhale vaporized cannabis in the evening of day 1, three times a day on days 2-4, and in the morning of day 5. Blood sampling was performed at 12-h intervals on days 1 and 5. The extent of chronic pain was also assessed daily. Pharmacokinetic investigations revealed no significant change in the area under the plasma concentration-time curves for either morphine or oxycodone after exposure to cannabis. Pain was significantly decreased (average 27%, 95% confidence interval (CI) 9, 46) after the addition of vaporized cannabis. We therefore concluded that vaporized cannabis augments the analgesic effects of opioids without significantly altering plasma opioid levels. The combination may allow for opioid treatment at lower doses with fewer side effects.


Asunto(s)
Analgésicos Opioides/uso terapéutico , Dolor Crónico/tratamiento farmacológico , Dronabinol/farmacología , Morfina/uso terapéutico , Oxicodona/uso terapéutico , Administración por Inhalación , Adulto , Analgésicos Opioides/administración & dosificación , Analgésicos Opioides/farmacocinética , Área Bajo la Curva , Preparaciones de Acción Retardada , Dronabinol/efectos adversos , Esquema de Medicación , Sinergismo Farmacológico , Femenino , Humanos , Masculino , Persona de Mediana Edad , Morfina/administración & dosificación , Morfina/farmacocinética , Oxicodona/administración & dosificación , Oxicodona/farmacocinética , Resultado del Tratamiento
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