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1.
Phys Rev Lett ; 129(22): 227702, 2022 Nov 23.
Artículo en Inglés | MEDLINE | ID: mdl-36493429

RESUMEN

The spin 1/2 entropy of electrons trapped in a quantum dot has previously been measured with great accuracy, but the protocol used for that measurement is valid only within a restrictive set of conditions. Here, we demonstrate a novel entropy measurement protocol that is universal for arbitrary mesoscopic circuits and apply this new approach to measure the entropy of a quantum dot hybridized with a reservoir. The experimental results match closely to numerical renormalization group (NRG) calculations for small and intermediate coupling. For the largest couplings investigated in this Letter, NRG calculations predict a suppression of spin entropy at the charge transition due to the formation of a Kondo singlet, but that suppression is not observed in the experiment.


Asunto(s)
Puntos Cuánticos , Citoesqueleto , Electrones , Entropía
2.
Entropy (Basel) ; 24(3)2022 Mar 17.
Artículo en Inglés | MEDLINE | ID: mdl-35327927

RESUMEN

Previous measurements utilizing Maxwell relations to measure change in entropy, S, demonstrated remarkable accuracy in measuring the spin-1/2 entropy of electrons in a weakly coupled quantum dot. However, these previous measurements relied upon prior knowledge of the charge transition lineshape. This had the benefit of making the quantitative determination of entropy independent of scale factors in the measurement itself but at the cost of limiting the applicability of the approach to simple systems. To measure the entropy of more exotic mesoscopic systems, a more flexible analysis technique may be employed; however, doing so requires a precise calibration of the measurement. Here, we give details on the necessary improvements made to the original experimental approach and highlight some of the common challenges (along with strategies to overcome them) that other groups may face when attempting this type of measurement.

3.
Cochrane Database Syst Rev ; 11: CD008720, 2016 11 16.
Artículo en Inglés | MEDLINE | ID: mdl-27852101

RESUMEN

BACKGROUND: In vitro maturation (IVM) is a fertility treatment that involves the transvaginal retrieval of immature oocytes, and their subsequent maturation and fertilisation. Although the live birth rate is lower than conventional in vitro fertilisation (IVF) with ovarian stimulation, it is a useful treatment, as it avoids the risk of ovarian hyperstimulation syndrome (OHSS). Women with polycystic ovaries (PCO) or polycystic ovarian syndrome (PCOS) are at an increased risk of OHSS. Thus, IVM may be a more useful treatment in this patient group.Strategies to maximise the maturation rates of the immature oocytes are important. This review focuses on the administration of human chorionic gonadotrophin (hCG) prior to immature oocyte retrieval. OBJECTIVES: To determine the effectiveness and safety of hCG priming in subfertile women who are undergoing IVM treatment in the context of assisted reproduction. SEARCH METHODS: We searched the following electronic databases up to 29 August 2016: Cochrane Gynaecology and Fertility Group Specialised Register of controlled trials, CENTRAL, MEDLINE, Embase, PsycINFO, and CINAHL. We also searched the trial registries ClinicalTrials.gov and WHO ICTPR to identify ongoing and registered trials. We sought recently published papers not yet indexed in the major databases, and reviewed the reference lists of reviews and retrieved studies as sources of potentially relevant studies. There were no language restrictions. SELECTION CRITERIA: We included randomised controlled trials (RCTs) that compared hCG priming with placebo or no priming in women undergoing IVM. We also included RCTs that compared different doses of hCG, or the timing of oocyte retrieval. The primary outcomes were live birth rate and miscarriage rate per woman randomised. DATA COLLECTION AND ANALYSIS: Two review authors independently selected studies for inclusion, and with a third author, assessed risk of bias and extracted data. We contacted the original authors where data were missing. For dichotomous outcomes, we used the Mantel-Haenszel method to calculate odds ratios (OR). For continuous outcomes, we calculated the mean differences (MD) between treatment groups. We assessed statistical heterogeneity using the I² statistic. We assessed the overall quality of the evidence using GRADE methods. MAIN RESULTS: We included four studies, with a total of 522 women, in the review. One of these studies did not report outcomes per woman randomised, and so was not included in formal analysis. Three studies investigated 10,000 units hCG priming compared to no priming. One study investigated 20,000 units hCG compared to 10,000 units hCG priming. Three studies only included women with PCOS (N = 122), while this was an exclusion criteria in the fourth study (N = 400).We rated all four studies as having an unclear risk of bias in more than one of the seven domains assessed. The quality of the evidence was low, the main limitations being lack of blinding and imprecision.When 10,000 units hCG priming was compared to no priming, we found no evidence of a difference in the live birth rates per woman randomised (OR 0.65, 95% confidence intervals (CI) 0.24 to 1.74; one RCT; N = 82; low quality evidence); miscarriage rate (OR 0.60, 95% CI 0.21 to 1.72; two RCTs; N = 282; I² statistic = 21%; low quality evidence), or clinical pregnancy rate (OR 0.52, 95% CI 0.26 to 1.03; two RCTs, N = 282, I² statistic = 0%, low quality evidence). Though inconclusive, our findings suggested that hCG may be associated with a reduction in clinical pregnancy rates; 22% of women who received no priming achieved pregnancy, while between 7% and 23% of women who received hCG priming did so.The study comparing 20,000 units hCG with 10,000 units hCG did not report sufficient data to enable us to calculate odds ratios.No studies reported on adverse events (other than miscarriage) or drug reactions. AUTHORS' CONCLUSIONS: This review found no conclusive evidence that hCG priming had an effect on live birth, pregnancy, or miscarriage rates in IVM. There was low quality evidence that suggested that hCG priming may reduce clinical pregnancy rates, however, these findings were limited by the small number of data included. As no data were available on adverse events (other than miscarriage) or on drug reactions, we could not adequately assess the safety of hCG priming. We need further evidence from well-designed RCTs before we can come to definitive conclusions about the role of hCG priming, and the optimal dose and timing.


Asunto(s)
Gonadotropina Coriónica/administración & dosificación , Técnicas de Maduración In Vitro de los Oocitos , Infertilidad Femenina , Índice de Embarazo , Sustancias para el Control de la Reproducción/administración & dosificación , Aborto Espontáneo/epidemiología , Adulto , Gonadotropina Coriónica/efectos adversos , Femenino , Humanos , Nacimiento Vivo/epidemiología , Recuperación del Oocito , Embarazo , Ensayos Clínicos Controlados Aleatorios como Asunto , Sustancias para el Control de la Reproducción/efectos adversos
4.
J Assist Reprod Genet ; 22(2): 81-8, 2005 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-15844733

RESUMEN

PURPOSE: To compare the efficiency and efficacy of two starting doses of recombinant FSH (follitropin-beta, Puregon) in women undergoing IVF treatment. METHODS: This prospective, randomized, double-blind, multicentric (N = 6) study included 192 women undergoing IVF using the long protocol of GnRH agonist who received either 100 IU or 200 IU of r-FSH per day. Gonadotropin dose adjustment was allowed after day 4 of stimulation. RESULTS: The average (SD) number of oocytes retrieved was 10.9 (5.4) and 12.2 (5.6) in the 100 IU and 200 IU group respectively (p = 0.067). The total doses of Puregon administered were 1887 IU and 2559 IU in the 100 IU and 200 IU group respectively. The number of transferable embryos, and the rates of pregnancies, cancelled cycles, miscarriages and adverse events including OHSS were comparable between the two groups. CONCLUSIONS: Women undergoing IVF have similar outcomes whether recombinant FSH is commenced in a dose of 100 IU or 200 IU for the first 4 days of stimulation.


Asunto(s)
Fertilización In Vitro , Hormona Folículo Estimulante Humana/uso terapéutico , Inducción de la Ovulación/métodos , Adulto , Relación Dosis-Respuesta a Droga , Método Doble Ciego , Femenino , Humanos , Oocitos , Estudios Prospectivos , Resultado del Tratamiento
5.
Fertil Steril ; 82(5): 1458-9, 2004 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-15533381

RESUMEN

Preretrieval priming with 10,000 IU hCG can improve oocyte maturation rates in vitro for women undergoing in vivo maturation treatment, though the optimum dose is unknown. This prospective, randomized, controlled trial demonstrated no improvement in oocyte maturation rates with 20,000 IU of hCG compared with 10,000 IU of hCG and therefore no benefit of the higher dose.


Asunto(s)
Gonadotropina Coriónica/administración & dosificación , Infertilidad Femenina/tratamiento farmacológico , Infertilidad Femenina/etiología , Síndrome del Ovario Poliquístico/complicaciones , Adulto , Senescencia Celular/efectos de los fármacos , Gonadotropina Coriónica/uso terapéutico , Relación Dosis-Respuesta a Droga , Femenino , Humanos , Infertilidad Femenina/fisiopatología , Oocitos/efectos de los fármacos , Cuidados Preoperatorios , Recolección de Tejidos y Órganos
6.
Neurosci Lett ; 357(3): 232-4, 2004 Mar 11.
Artículo en Inglés | MEDLINE | ID: mdl-15003292

RESUMEN

Immunocytochemistry was used to demonstrate the presence of beta-endorphin and alpha-MSH, and in situ hybridisation was used to study the presence of pro-opiomelanocortin (POMC) mRNA, in spinal motoneurones, up to 8 days following the administration of a single dose of acrylamide in mice. The proportions of POMC-mRNA positive neurones, beta-endorphin-immunoreactive neurones and alpha-MSH-immunoreactive neurones were significantly increased in the treated animals compared to controls. It seems likely that upregulation of the POMC gene precedes acrylamide-induced neuropathy.


Asunto(s)
Acrilamida/administración & dosificación , Regulación de la Expresión Génica/efectos de los fármacos , Neuronas Motoras/efectos de los fármacos , Proopiomelanocortina/metabolismo , Acrilamida/farmacología , Animales , Recuento de Células/métodos , Inmunohistoquímica/métodos , Hibridación in Situ/métodos , Masculino , Ratones , Neuronas Motoras/metabolismo , Proopiomelanocortina/genética , ARN Mensajero/efectos de los fármacos , ARN Mensajero/metabolismo , Médula Espinal/citología , Médula Espinal/efectos de los fármacos , Factores de Tiempo , Regulación hacia Arriba , alfa-MSH/metabolismo , betaendorfina/metabolismo
8.
Am J Obstet Gynecol ; 186(4): 684-9, 2002 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-11967491

RESUMEN

OBJECTIVE: To select women who will benefit most from in vitro maturation (IVM) of oocytes treatment, this study was undertaken to examine the ability of a transvaginal ultrasonography to predict the number of immature oocytes collected from unstimulated ovaries. STUDY DESIGN: The relationship between the number of immature oocytes retrieved and the pregnancy rate was assessed in 189 IVM treatment cycles. In 96 consecutive cycles, an early follicular phase transvaginal ultrasonographic measurement of the antral follicle count (AFC), ovarian volume, and peak ovarian stromal blood flow velocity (Vmax) was performed, and the results were correlated with the number of immature oocytes. RESULTS: The clinical pregnancy rate increased significantly with the number of oocytes retrieved (P =.02) and was 26.8% (15/56) in those with >10 immature oocytes. The AFC, ovarian volume, and ovarian stromal Vmax were all predictive of the number of oocytes retrieved, but when the other factors were controlled by multiple regression analysis the AFC was the only significant predictor (P <.001). CONCLUSIONS: Pregnancy rates after IVM correlate with the number of immature oocytes retrieved. This is best predicted by an ultrasonographic assessment of the AFC.


Asunto(s)
Recuento de Células , Fertilización In Vitro , Fase Folicular , Oocitos/fisiología , Ovario/diagnóstico por imagen , Recolección de Tejidos y Órganos , Velocidad del Flujo Sanguíneo , Células Cultivadas , Femenino , Humanos , Modelos Lineales , Folículo Ovárico/citología , Folículo Ovárico/diagnóstico por imagen , Ovario/irrigación sanguínea , Embarazo , Ultrasonografía
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