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1.
Rev Sci Instrum ; 94(4)2023 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-38081262

RESUMEN

We describe the first implementation of a Josephson Traveling Wave Parametric Amplifier (JTWPA) in an axion dark matter search. The operation of the JTWPA for a period of about two weeks achieved sensitivity to axion-like particle dark matter with axion-photon couplings above 10-13 Ge V-1 over a narrow range of axion masses centered around 19.84 µeV by tuning the resonant frequency of the cavity over the frequency range of 4796.7-4799.5 MHz. The JTWPA was operated in the insert of the axion dark matter experiment as part of an independent receiver chain that was attached to a 0.56-l cavity. The ability of the JTWPA to deliver high gain over a wide (3 GHz) bandwidth has engendered interest from those aiming to perform broadband axion searches, a longstanding goal in this field.

2.
Phys Rev Lett ; 131(10): 101002, 2023 Sep 08.
Artículo en Inglés | MEDLINE | ID: mdl-37739367

RESUMEN

We report the first result of a direct search for a cosmic axion background (CaB)-a relativistic background of axions that is not dark matter-performed with the axion haloscope, the Axion Dark Matter eXperiment (ADMX). Conventional haloscope analyses search for a signal with a narrow bandwidth, as predicted for dark matter, whereas the CaB will be broad. We introduce a novel analysis strategy, which searches for a CaB induced daily modulation in the power measured by the haloscope. Using this, we repurpose data collected to search for dark matter to set a limit on the axion photon coupling of a CaB originating from dark matter cascade decay via a mediator in the 800-995 MHz frequency range. We find that the present sensitivity is limited by fluctuations in the cavity readout as the instrument scans across dark matter masses. Nevertheless, we suggest that these challenges can be surmounted using superconducting qubits as single photon counters, and allow ADMX to operate as a telescope searching for axions emerging from the decay of dark matter. The daily modulation analysis technique we introduce can be deployed for various broadband rf signals, such as other forms of a CaB or even high-frequency gravitational waves.

3.
Phys Rev Lett ; 127(26): 261803, 2021 Dec 24.
Artículo en Inglés | MEDLINE | ID: mdl-35029490

RESUMEN

We report the results from a haloscope search for axion dark matter in the 3.3-4.2 µeV mass range. This search excludes the axion-photon coupling predicted by one of the benchmark models of "invisible" axion dark matter, the Kim-Shifman-Vainshtein-Zakharov model. This sensitivity is achieved using a large-volume cavity, a superconducting magnet, an ultra low noise Josephson parametric amplifier, and sub-Kelvin temperatures. The validity of our detection procedure is ensured by injecting and detecting blind synthetic axion signals.

4.
Rev Sci Instrum ; 92(12): 124502, 2021 Dec 01.
Artículo en Inglés | MEDLINE | ID: mdl-34972408

RESUMEN

Axion dark matter experiment ultra-low noise haloscope technology has enabled the successful completion of two science runs (1A and 1B) that looked for dark matter axions in the 2.66-3.1 µeV mass range with Dine-Fischler-Srednicki-Zhitnisky sensitivity [Du et al., Phys. Rev. Lett. 120, 151301 (2018) and Braine et al., Phys. Rev. Lett. 124, 101303 (2020)]. Therefore, it is the most sensitive axion search experiment to date in this mass range. We discuss the technological advances made in the last several years to achieve this sensitivity, which includes the implementation of components, such as the state-of-the-art quantum-noise-limited amplifiers and a dilution refrigerator. Furthermore, we demonstrate the use of a frequency tunable microstrip superconducting quantum interference device amplifier in run 1A, and a Josephson parametric amplifier in run 1B, along with novel analysis tools that characterize the system noise temperature.

5.
Phys Rev Lett ; 124(10): 101303, 2020 Mar 13.
Artículo en Inglés | MEDLINE | ID: mdl-32216421

RESUMEN

This Letter reports on a cavity haloscope search for dark matter axions in the Galactic halo in the mass range 2.81-3.31 µeV. This search utilizes the combination of a low-noise Josephson parametric amplifier and a large-cavity haloscope to achieve unprecedented sensitivity across this mass range. This search excludes the full range of axion-photon coupling values predicted in benchmark models of the invisible axion that solve the strong CP problem of quantum chromodynamics.

6.
Phys Rev Lett ; 120(15): 151301, 2018 Apr 13.
Artículo en Inglés | MEDLINE | ID: mdl-29756850

RESUMEN

This Letter reports the results from a haloscope search for dark matter axions with masses between 2.66 and 2.81 µeV. The search excludes the range of axion-photon couplings predicted by plausible models of the invisible axion. This unprecedented sensitivity is achieved by operating a large-volume haloscope at subkelvin temperatures, thereby reducing thermal noise as well as the excess noise from the ultralow-noise superconducting quantum interference device amplifier used for the signal power readout. Ongoing searches will provide nearly definitive tests of the invisible axion model over a wide range of axion masses.

7.
Phys Rev Lett ; 121(26): 261302, 2018 Dec 28.
Artículo en Inglés | MEDLINE | ID: mdl-30636160

RESUMEN

The µeV axion is a well-motivated extension to the standard model. The Axion Dark Matter eXperiment (ADMX) collaboration seeks to discover this particle by looking for the resonant conversion of dark-matter axions to microwave photons in a strong magnetic field. In this Letter, we report results from a pathfinder experiment, the ADMX "Sidecar," which is designed to pave the way for future, higher mass, searches. This testbed experiment lives inside of and operates in tandem with the main ADMX experiment. The Sidecar experiment excludes masses in three widely spaced frequency ranges (4202-4249, 5086-5799, and 7173-7203 MHz). In addition, Sidecar demonstrates the successful use of a piezoelectric actuator for cavity tuning. Finally, this publication is the first to report data measured using both the TM_{010} and TM_{020} modes.

8.
J Viral Hepat ; 19(2): 94-102, 2012 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-22239499

RESUMEN

Approximately 50% of patients with hepatitis C virus (HCV) genotype 1 treated with peginterferon alfa-2a/ribavirin discontinue treatment early or experience a suboptimal response despite 48 weeks of therapy. The objective of this analysis was to develop a model to identify nonrapid virologic response (non-RVR) patients who may be candidates for intensified therapy that would increase treatment response. The retrospective analysis included non-RVR patients from four trials of 48-week peginterferon alfa-2a/ribavirin treatment. Patients were grouped into those who cleared virus between weeks 5 and 12 (complete early virologic responders, cEVR) or between weeks 13 and 24 (slow responders). A model was developed to predict relapse at the end of follow-up (week 72). An optimal model was evaluated and compared with current practice by using receiver operating characteristic curves, sensitivity and specificity. In total, 539 non-RVR patients were eligible for analysis of which 72% experienced cEVR and 28% were slow responders. Variables associated with relapse included age, ethnicity, baseline HCV RNA and interval of time to HCV RNA undetectable. The optimal model was most accurate at predicting patients at risk for relapse. The practice of considering treatment intensification (e.g. extending treatment duration) in all slow responders was less accurate but likely most practical. A week 4 HCV <2-log reduction was the earliest but least accurate marker. We developed a model that could identify non-RVR patients at high risk for relapse after 48 weeks of peginterferon alfa-2a plus ribavirin and who may benefit from intensified therapy to reduce this risk of relapse.


Asunto(s)
Antivirales/administración & dosificación , Hepacivirus/aislamiento & purificación , Hepatitis C Crónica/tratamiento farmacológico , Hepatitis C Crónica/virología , Interferón-alfa/administración & dosificación , Polietilenglicoles/administración & dosificación , Ribavirina/administración & dosificación , Carga Viral , Adulto , Anciano , Femenino , Genotipo , Hepacivirus/clasificación , Hepacivirus/genética , Humanos , Masculino , Persona de Mediana Edad , Modelos Estadísticos , Pronóstico , Proteínas Recombinantes/administración & dosificación , Recurrencia , Estudios Retrospectivos , Medición de Riesgo , Sensibilidad y Especificidad , Resultado del Tratamiento
9.
J Biotechnol ; 156(2): 100-7, 2011 Nov 10.
Artículo en Inglés | MEDLINE | ID: mdl-21893114

RESUMEN

Group A rotavirus is a major leading cause of diarrhea in mammalian species worldwide. In Argentina, bovine rotavirus (BRV) is the main cause of neonatal diarrhea in calves. VP4, one of the outermost capsid proteins, is involved in various virus functions. Rotavirus infectivity requires proteolytic cleavage of VP4, giving an N-terminal non-glycosilated sialic acid-recognizing domain (VP8*), and a C-terminal fragment (VP5*) that remains associated with the virion. VP8* subunit is the major determinant of the viral infectivity and one of the neutralizing antigens. In this work, the C486 BRV VP8* protein was produced in tobacco chloroplasts. Transplastomic plants were obtained and characterized by Southern blot, northern blot and western blot. VP8* was highly stable in the transplastomic leaves, and formed insoluble aggregates that were partially solubilized by sonication. The recombinant protein yield was 600 µg/g of fresh tissue (FT). Both the soluble and insoluble fractions of the VP8* plant extracts were able to induce a strong immune response in female mice as measured by ELISA and virus neutralization test. Most important, suckling mice born to immunized dams were protected against oral challenge with virulent rotavirus. Results presented here contribute to demonstrate the feasibility of using antigens expressed in transplastomic plants for the development of subunit vaccines.


Asunto(s)
Proteínas de la Cápside/inmunología , Infecciones por Rotavirus/prevención & control , Vacunas contra Rotavirus , Rotavirus , Animales , Animales Lactantes , Proteínas de la Cápside/genética , Bovinos , Femenino , Ratones , Estructura Terciaria de Proteína/genética , Proteínas Recombinantes/genética , Proteínas Recombinantes/inmunología , Infecciones por Rotavirus/inmunología , Vacunas contra Rotavirus/administración & dosificación , Vacunas contra Rotavirus/genética , Vacunas contra Rotavirus/inmunología , Nicotiana , Vacunación , Vacunas de Subunidad/administración & dosificación , Vacunas de Subunidad/genética , Vacunas de Subunidad/inmunología
10.
Aliment Pharmacol Ther ; 27(7): 542-51, 2008 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-18208570

RESUMEN

BACKGROUND: Patients with chronic hepatitis C virus and advanced fibrosis or cirrhosis are at risk for disease progression and hepatic decompensation. AIM: To determine the effects on hepatic histology of treatment with peginterferon alfa-2a (90 or 180 mug/week) or interferon alfa-2a (3 million units three times weekly) for 48 weeks in patients with paired biopsies. METHODS: Liver biopsies were obtained at baseline and 6 months after end of treatment. Histological and virological responses were compared. RESULTS: Patients attaining sustained virological response (n = 40) demonstrated the greatest improvements in fibrosis (-1.0, P < 0.0001) and inflammation (-0.65, P < 0.0001). Patients who cleared hepatitis C virus during treatment, but later relapsed (n = 59), experienced less improvement in fibrosis (-0.04, P < 0.0001) and inflammation (-0.14, P = 0.0768). Nonresponders (n = 85) showed no significant improvement in inflammation or fibrosis. Multiple regression analysis showed that the only factors contributing to improvement in fibrosis were sustained virological response (vs. nonresponder, P = 0.0005; vs. relapse, P = 0.7525) and body mass index < or =30 kg/m2 (P = 0.0995). CONCLUSIONS: These findings indicate that virological response to peginterferon alfa-2a improves inflammation and fibrosis in hepatitis C virus patients with advanced fibrosis or cirrhosis. Improving virological response and maintaining ideal body weight are critical for achieving optimal histological outcomes in hepatitis C virus patients.


Asunto(s)
Antivirales/uso terapéutico , Hepatitis C/tratamiento farmacológico , Interferón-alfa/uso terapéutico , Cirrosis Hepática/tratamiento farmacológico , Polietilenglicoles/uso terapéutico , Antivirales/administración & dosificación , Esquema de Medicación , Femenino , Hepacivirus/efectos de los fármacos , Hepatitis C/complicaciones , Hepatitis C/patología , Humanos , Interferón alfa-2 , Interferón-alfa/administración & dosificación , Cirrosis Hepática/complicaciones , Cirrosis Hepática/patología , Modelos Logísticos , Masculino , Persona de Mediana Edad , Polietilenglicoles/administración & dosificación , Proteínas Recombinantes , Resultado del Tratamiento
11.
J Am Vet Med Assoc ; 206(6): 807-11, 1995 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-7759332

RESUMEN

Seventy dogs were included in a randomized, controlled, multicenter trial to test the efficacy of carprofen (2.2 mg/kg of body weight, PO, q 12 h) for relief of clinical signs associated with osteoarthritis. Thirty-six dogs received carprofen, and 34 received a placebo. Response of the dogs was evaluated by comparing results of force plate examination and a graded lameness examination performed before and immediately after 2 weeks of treatment, and by obtaining a subjective assessment of the dog's posttreatment condition from owners and participating veterinarians. A physical examination, CBC, serum biochemical analyses, urinalysis, and fecal occult blood test were performed before and after treatment to monitor safety. For force plate evaluation, the odds ratio was 3.3, meaning that a dog treated with carprofen was 3.3 times more likely to have a positive response than was a dog treated with the placebo. For evaluation by a veterinarian, the odds ratio was 3.5, and for owner evaluation, the odds ratio was 4.2. Institution where dogs were treated did not have a significant effect on results. A variety of reactions that may have been related to the medication (placebo or carprofen) were recorded; however, none were considered serious. Serum alanine aminotransferase activity was high in 3 dogs (2 that received placebo and 1 that received carprofen) at the conclusion of treatment; none of the 3 dogs were clinically ill. Ten dogs (5 that received placebo and 5 that received caprofen) had negative pretreatment and positive posttreatment fecal occult blood test results.


Asunto(s)
Antiinflamatorios no Esteroideos/uso terapéutico , Carbazoles/uso terapéutico , Enfermedades de los Perros/tratamiento farmacológico , Osteoartritis/veterinaria , Animales , Antiinflamatorios no Esteroideos/efectos adversos , Carbazoles/efectos adversos , Perros , Femenino , Masculino , Osteoartritis/tratamiento farmacológico , Estudios Prospectivos
12.
J AOAC Int ; 78(2): 371-4, 1995.
Artículo en Inglés | MEDLINE | ID: mdl-7756851

RESUMEN

A statistical method is proposed to establish milk discard time for the data set described in Part I (preceding paper). Results are compared with those from the Food and Drug Administration (FDA)-recommended method. The milk discard time is established on the basis of a calculated tolerance limit. This limit provides 95% confidence that 99% of the population residue would assay below the permitted concentration (10 ppb for SDM). Unlike the FDA method, the proposed method allows easy calculation and requires no assumptions in drug depletion rate over time. For a permitted concentration of 10 ppb, both methods confirm the present 60-h discard time for SDM when it is assumed that no more than 1/3 of the milk came from treated cows.


Asunto(s)
Residuos de Medicamentos/análisis , Leche/química , Sulfadimetoxina/análisis , Animales , Bovinos , Femenino , Concentración Máxima Admisible , Estadística como Asunto/métodos , Sulfadimetoxina/administración & dosificación , Sulfadimetoxina/farmacocinética , Factores de Tiempo , Estados Unidos , United States Food and Drug Administration
13.
J Anim Sci ; 70(8): 2568-73, 1992 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-1506319

RESUMEN

Thirty-five crossbred wethers were used to determine the concentrations of alpha-tocopherol in serum and tissues after oral supplementation of six different vitamin E product forms. Five wethers were assigned to each of the following treatments: 1) control, no supplemental vitamin E (C), 2) emulsifiable DL-alpha-tocopheryl acetate-dry (Rovimix E-50% SD), 3) nonemulsifiable DL-alpha-tocopheryl acetate-dry (Rovimix E-50% Ads), 4) emulsifiable DL-alpha-tocopheryl acetate-liquid (Rovimix E-40% Dispersible Liquid Concentrate [DLC]); 5) emulsifiable DL-alpha-tocopherol-liquid (Hoffmann-La Roche, E-40% DLC alcohol), 6) micellized DL-alpha-tocopheryl acetate-liquid (Bioglan, Inc., E-20%); and 7) micellized DL-alpha-tocopherol-liquid (Bioglan, Inc., E-20%). Animals were supplemented daily with 1,000 IU of their respective vitamin E sources for 56 d. Blood samples were collected daily from d 0 to 7 and weekly until d 56. Animals were subsequently killed by exsanguination after stunning and eight different tissues were collected for alpha-tocopherol analysis. There were effects of day, treatment, and day x treatment interaction on serum alpha-tocopherol. All supplemented groups were higher in serum alpha-tocopherol concentration than were the C wethers. The emulsifiable vitamin E alcohol liquid product form (Treatment 5) yielded higher (P less than .01) serum alpha-tocopherol concentration than the emulsifiable acetate liquid product (Treatment 4). Sheep on Treatment 5 reached maximum concentration on d 1, sheep on Treatment 6 on d 2, and the sheep on the remaining Treatments by d 3. Blood sera alpha-tocopherol concentrations stabilized by d 6 in all supplemented groups.(ABSTRACT TRUNCATED AT 250 WORDS)


Asunto(s)
Ovinos/metabolismo , Vitamina E/farmacocinética , alfa-Tocoferol/análogos & derivados , Administración Oral , Alimentación Animal , Animales , Disponibilidad Biológica , Emulsiones , Alimentos Fortificados , Hígado/metabolismo , Masculino , Micelas , Miocardio/metabolismo , Páncreas/metabolismo , Tocoferoles , Vitamina E/administración & dosificación , Vitamina E/análogos & derivados , Vitamina E/sangre
14.
J Anim Sci ; 70(8): 2562-7, 1992 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-1506318

RESUMEN

Forty-three crossbred wethers weighing 35 to 60 kg were used to investigate the effect of a single i.m. injection of DL-alpha-tocopherol (DL-alpha-ol). Animals were offered 1 kg/d of a basal diet containing 25 ppm of vitamin E. Lambs were randomly assigned to one of five DL-alpha-ol injection treatments as follows: 1) control (placebo, 0 IU), 2) 125 IU, 3) 250 IU, 4) 500 IU, or 5) 1,000 IU. Blood samples were taken via jugular venipuncture on d 1 before treatment administration and thereafter at designated intervals up to 360 h postinjection. The i.m. injections of DL-alpha-ol irrespective of dose increased serum alpha-tocopherol. Results showed a dose x time interaction (P less than .0001) across all treatments. Serum alpha-tocopherol increased rapidly to maximum concentration during the first 8 to 12 h for all non-zero treatments, followed by a rapid decline to pretreatment values. The mean serum alpha-tocopherol concentration at 0 h was .69 microgram/mL. Estimated peak serum alpha-tocopherol concentrations +/- SE were 6.68 +/- 1.04, 9.62 +/- 1.04, 21.66 +/- 2.37, and 50.75 +/- 7.05 micrograms/mL for Treatments 2 through 5, respectively. Results showed a quadratic dose effect (P less than .0003) on maximum response with apparently no effect on time taken to reach this peak. There was also a quadratic dose effect (P less than .0001) on the area under the concentration-time curve. The time taken for serum alpha-tocopherol to return to pretreatment levels increased with dose (56, 64, 67, and 74 h, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)


Asunto(s)
Ovinos/metabolismo , Vitamina E/farmacocinética , Análisis de Varianza , Animales , Relación Dosis-Respuesta a Droga , Inyecciones Intramusculares/veterinaria , Modelos Lineales , Masculino , Distribución Aleatoria , Vitamina E/administración & dosificación , Vitamina E/sangre
15.
Am J Vet Res ; 52(5): 662-4, 1991 May.
Artículo en Inglés | MEDLINE | ID: mdl-1854089

RESUMEN

The thiamylal sparing effect of midazolam was studied in 30 healthy Beagle and mixed-breed dogs. Using a replicated Latin square design, all dogs were given placebo (saline solution) and 0.025, 0.05, 0.1, and 0.2 mg of midazolam/kg of body weight prior to IV administration of thiamylal sodium. The 0.1 and 0.2 mg/kg dosages significantly decreased the amount of thiamylal required to obtund swallowing reflex and easily achieve endotracheal intubation. Midazolam at 0.1 and 0.2 mg/kg reduced thiamylal requirement by 16.4% and 18.9%, respectively, whereas the 0.05 mg/kg dosage decreased thiamylal requirement by only 6.8%. The 0.2 mg/kg dosage did not further decrease thiamylal requirement beyond that achieved with the 0.1 mg/kg dosage of midazolam. This study demonstrates that the preanesthetic IV administration of midazolam reduces the thiamylal dose necessary to accomplish intubation. The optimal preanesthetic dosage (lowest dosage with significant effect) was 0.1 mg/kg.


Asunto(s)
Perros/fisiología , Midazolam/uso terapéutico , Medicación Preanestésica/veterinaria , Tiamilal , Animales , Temperatura Corporal/efectos de los fármacos , Deglución/efectos de los fármacos , Interacciones Farmacológicas , Frecuencia Cardíaca/efectos de los fármacos , Intubación Intratraqueal/veterinaria , Distribución Aleatoria , Respiración/efectos de los fármacos , Factores de Tiempo
16.
17.
J Clin Lab Anal ; 3(6): 350-4, 1989.
Artículo en Inglés | MEDLINE | ID: mdl-2559178

RESUMEN

We have compared two IgM-specific cytomegalovirus (CMV) antibody assays, an immunofluorescence assay (IFA-M) and an enzyme-linked antigen immunoassay (ELA-M), with an assay for CMV total antibody (ELISA) and viral culture for the detection of active CMV infection in renal transplant recipients. Of 75 patients (49 ELISA negative pretransplant, 26 ELISA positive), CMV-specific IgM was detected in 35 (27 ELISA negative pretransplant, 8 ELISA positive) using the IFA-M assay and in 25 (16 ELISA negative pretransplant, 9 ELISA positive) using the ELA-M test. Of the 25 patients identified as positive by ELA-M, 21 had positive viral cultures post-transplant, two seronegative patients had evidence of infection indicated by post-transplant seroconversion, and two patients were seropositive pretransplant but remained viral culture negative throughout the follow-up period. ELA-M and CMV total antibody ELISA detected primary infection in renal transplant recipients equally well, but ELA-M was found to be superior to ELISA and IFA-M for detecting reinfection and reactivation infections.


Asunto(s)
Anticuerpos Antivirales/análisis , Infecciones por Citomegalovirus/inmunología , Citomegalovirus/inmunología , Inmunoglobulina M/análisis , Trasplante de Riñón/inmunología , Citomegalovirus/aislamiento & purificación , Infecciones por Citomegalovirus/etiología , Ensayo de Inmunoadsorción Enzimática , Humanos , Terapia de Inmunosupresión , Trasplante de Riñón/efectos adversos , Pruebas Serológicas
19.
J Clin Microbiol ; 26(1): 133-5, 1988 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-2830297

RESUMEN

Five hundred blood donors were evaluated for cytomegalovirus (CMV) viruria, antibody to CMV early antigens (EA-ab), CMV seropositivity by two screening assays, and CMV-specific immunoglobulin M by two methods. Three donors were viruric, EA-ab positive, and seropositive; two viruric donors were immunoglobulin M positive.


Asunto(s)
Anticuerpos Antivirales/análisis , Antígenos Virales/inmunología , Donantes de Sangre , Infecciones por Citomegalovirus/diagnóstico , Citomegalovirus/inmunología , Proteínas Inmediatas-Precoces , Orina/microbiología , Citomegalovirus/aislamiento & purificación , Ensayo de Inmunoadsorción Enzimática , Humanos , Inmunoglobulina M/análisis , Pruebas de Fijación de Látex
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