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1.
Phys Rev Lett ; 129(22): 227702, 2022 Nov 23.
Artigo em Inglês | MEDLINE | ID: mdl-36493429

RESUMO

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.


Assuntos
Pontos Quânticos , Citoesqueleto , Elétrons , Entropia
2.
Entropy (Basel) ; 24(3)2022 Mar 17.
Artigo em Inglês | MEDLINE | ID: mdl-35327927

RESUMO

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.
Artigo em Inglês | MEDLINE | ID: mdl-27852101

RESUMO

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.


Assuntos
Gonadotropina Coriônica/administração & dosagem , Técnicas de Maturação in Vitro de Oócitos , Infertilidade Feminina , Taxa de Gravidez , Substâncias para o Controle da Reprodução/administração & dosagem , Aborto Espontâneo/epidemiologia , Adulto , Gonadotropina Coriônica/efeitos adversos , Feminino , Humanos , Nascido Vivo/epidemiologia , Recuperação de Oócitos , Gravidez , Ensaios Clínicos Controlados Aleatórios como Assunto , Substâncias para o Controle da Reprodução/efeitos adversos
4.
J Assist Reprod Genet ; 22(2): 81-8, 2005 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-15844733

RESUMO

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.


Assuntos
Fertilização in vitro , Hormônio Foliculoestimulante Humano/uso terapêutico , Indução da Ovulação/métodos , Adulto , Relação Dose-Resposta a Droga , Método Duplo-Cego , Feminino , Humanos , Oócitos , Estudos Prospectivos , Resultado do Tratamento
5.
Fertil Steril ; 82(5): 1458-9, 2004 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-15533381

RESUMO

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.


Assuntos
Gonadotropina Coriônica/administração & dosagem , Infertilidade Feminina/tratamento farmacológico , Infertilidade Feminina/etiologia , Síndrome do Ovário Policístico/complicações , Adulto , Senescência Celular/efeitos dos fármacos , Gonadotropina Coriônica/uso terapêutico , Relação Dose-Resposta a Droga , Feminino , Humanos , Infertilidade Feminina/fisiopatologia , Oócitos/efeitos dos fármacos , Cuidados Pré-Operatórios , Coleta de Tecidos e Órgãos
6.
Neurosci Lett ; 357(3): 232-4, 2004 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-15003292

RESUMO

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.


Assuntos
Acrilamida/administração & dosagem , Regulação da Expressão Gênica/efeitos dos fármacos , Neurônios Motores/efeitos dos fármacos , Pró-Opiomelanocortina/metabolismo , Acrilamida/farmacologia , Animais , Contagem de Células/métodos , Imuno-Histoquímica/métodos , Hibridização In Situ/métodos , Masculino , Camundongos , Neurônios Motores/metabolismo , Pró-Opiomelanocortina/genética , RNA Mensageiro/efeitos dos fármacos , RNA Mensageiro/metabolismo , Medula Espinal/citologia , Medula Espinal/efeitos dos fármacos , Fatores de Tempo , Regulação para Cima , alfa-MSH/metabolismo , beta-Endorfina/metabolismo
8.
Am J Obstet Gynecol ; 186(4): 684-9, 2002 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-11967491

RESUMO

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.


Assuntos
Contagem de Células , Fertilização in vitro , Fase Folicular , Oócitos/fisiologia , Ovário/diagnóstico por imagem , Coleta de Tecidos e Órgãos , Velocidade do Fluxo Sanguíneo , Células Cultivadas , Feminino , Humanos , Modelos Lineares , Folículo Ovariano/citologia , Folículo Ovariano/diagnóstico por imagem , Ovário/irrigação sanguínea , Gravidez , Ultrassonografia
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