540 research outputs found

    Local and nonlocal contributions to the linear spectroscopy of light-harvesting antenna systems

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    In this paper the circular dichroism and absorption spectra of the LH2 complex of Rhodopseudomonas acidophila, for which the atomic structure is known, are analyzed. We show that an analysis based on the distribution of the excitations in real space, and their correlations, to unravel the relation between the atomic structure of the light-harvesting complex and its excitonic properties, is particularly successful. Starting from molecular expressions for the linear susceptibility, we demonstrate that linear spectra can be viewed as originating from the product of coherence correlation functions and geometric structure factors. Effects of homogeneous and inhomogeneous broadening can be incorporated in a natural way and lead to a definition of exciton length as the distance over which coherence correlation functions decay. 1

    Linear dichroism of CdSe nanodots: Large anisotropy of the band-gap absorption induced by ground-state dipole moments

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    We measured the electric field induced linear dichroism for a wide range of sizes of CdSe nanocrystals. Large ground-state dipole moments were observed, especially for the smallest crystals. In these, we found a very large anisotropy of the absorption and most of the dipole strength is along the direction of the ground-state dipole moment. For the anisotropy, we propose a mechanism for intensity borrowing from intraband transitions, induced by the field of the ground-state dipole moment. © 2008 The American Physical Society

    Bank debt and trade credit for SMEs in Europe: firm-, industry-, and country-level determinants

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    This paper examines differences in the ability to obtain capital—bank loans and trade credit—between firms, industries, and countries using survey data on European small and medium-sized enterprises (SMEs) from 2009 to 2014. The results show that firm age and firm size are positively linked to SMEs’ access to bank loans, but only firm size is positively related to the provision of trade credit. The results also provide em- pirical support for a complementary rather than a sub- stitutive effect between bank loans and trade credit. Manufacturing SMEs have a significantly higher likeli- hood of receiving bank loans and trade credit than non- manufacturing SMEs. We find differences across coun- tries in terms of the relevance of firm age and firm size for obtaining capital. In addition, we point at specific country-level variables that explain why obtaining credit is easier in some countries. We perform additional anal- yses to confirm our baseline results and provide direc- tions for future research.Coherent privaatrech

    Growth, body composition, and endocrine-metabolic profiles of individuals with Kleefstra syndrome provide directions for clinical management and translational studies

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    Mendelian neurodevelopmental disorders caused by variants in genes encoding chromatin modification can be categorized as Mendelian disorders of the epigenetic machinery (MDEMs). These disorders have significant overlap in molecular pathways and phenotypes including intellectual disability, short stature, and obesity. Among the MDEMs is Kleefstra syndrome (KLFS), which is caused by haploinsufficiency of EHMT1. Preclinical studies have identified metabolic dysregulation and obesity in KLFS models, but proper clinical translation lacks. In this study, we aim to delineate growth, body composition, and endocrine-metabolic characteristics in a total of 62 individuals with KLFS. Our results revealed a high prevalence of childhood-onset overweight/obesity (60%; 28/47) with disproportionately high body fat percentage, which aligns perfectly with previous preclinical studies. Short stature was common (33%), likely due to advanced skeletal maturation. Endocrine-metabolic investigations showed thyroid dysregulation (22%; 9/41), elevated triglycerides, and decreased blood ammonia levels. Moreover, hand radiographs identified decreased bone mineralization (57%; 8/14) and negative ulnar variance (71%; 10/14). Our findings indicate a high (cardio)metabolic risk in KLFS. Therefore, we recommend monitoring of weight and endocrine-metabolic profile. Supporting a healthy lifestyle and screening of bone mineralization is advised. Our comprehensive results support translational research and contribute to a better understanding of MDEM-associated phenotypes

    Growth, body composition, and endocrine-metabolic profiles of individuals with Kleefstra syndrome provide directions for clinical management and translational studies

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    Mendelian neurodevelopmental disorders caused by variants in genes encoding chromatin modification can be categorized as Mendelian disorders of the epigenetic machinery (MDEMs). These disorders have significant overlap in molecular pathways and phenotypes including intellectual disability, short stature, and obesity. Among the MDEMs is Kleefstra syndrome (KLFS), which is caused by haploinsufficiency of EHMT1. Preclinical studies have identified metabolic dysregulation and obesity in KLFS models, but proper clinical translation lacks. In this study, we aim to delineate growth, body composition, and endocrine-metabolic characteristics in a total of 62 individuals with KLFS. Our results revealed a high prevalence of childhood-onset overweight/obesity (60%; 28/47) with disproportionately high body fat percentage, which aligns perfectly with previous preclinical studies. Short stature was common (33%), likely due to advanced skeletal maturation. Endocrine-metabolic investigations showed thyroid dysregulation (22%; 9/41), elevated triglycerides, and decreased blood ammonia levels. Moreover, hand radiographs identified decreased bone mineralization (57%; 8/14) and negative ulnar variance (71%; 10/14). Our findings indicate a high (cardio)metabolic risk in KLFS. Therefore, we recommend monitoring of weight and endocrine-metabolic profile. Supporting a healthy lifestyle and screening of bone mineralization is advised. Our comprehensive results support translational research and contribute to a better understanding of MDEM-associated phenotypes

    Lumbar puncture for treating acute hydrocephalus after aneurysmal subarachnoid haemorrhage

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    Background: External ventricular drainage (EVD) for acute hydrocephalus after aneurysmal subarachnoid haemorrhage (aSAH) carries a risk of complications. We studied the proportion of patients in whom EVD can be avoided by treating acute hydrocephalus with ≥1 lumbar punctures (LP). Methods: From a prospectively collected database, we retrieved data on all aSAH patients admitted between 2007 and 2017 who developed acute hydrocephalus (i.e. neurological deterioration and ventricular enlargement <72 h after aSAH). Our regime is to consider LP as initial treatment. We calculated the proportions of patients (with corresponding 95% confidence interval (CI)) who improved after the initial LP and the extent of clinical improvement, the proportions of patients who were treated with only ≥1 LP(s), and those of patients needing continuous external ventricular or external lumbar drainage, or permanent ventriculoperitoneal or lumboperitoneal drainage. Results: Of 1391 consecutive aSAH patients, 473 (34%) had acute hydrocephalus, of whom 388 (82%) were treated. Of the 86 patients with LP as initial treatment, 70 (81% [95% CI 72–88]) showed initial improvement (with increase in median Glasgow Coma Score from 10 (IQR 7–12) to 12 (IQR 9–14) after initial LP), 39 (45% [95% CI 35–56]) improved with LP only, 41 (48% [95% CI 37–58]) needed continuous drainage and six (7% [95% CI 3–14]) needed permanent drainage. Conclusion: Around half the patients treated with LP for deterioration from acute hydrocephalus after aSAH does not require continuous extraventicular or extralumbar drainage

    Do Surgical Interventions Influence Psychosexual and Cosmetic Outcomes in Women with Disorders of Sex Development?

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    Clinical practice developed to promote psychosexual well-being in DSD is under scrutiny. Although techniques for genital surgery have much improved lately, long-term studies on psychosexual functioning and cosmetic outcome on which to base treatment and counseling are scarce. We studied 91 women with a DSD. Feminizing surgery was performed in 64% of the women; in 60% of them, resurgery in puberty was needed after a single-stage procedure. Both patients and gynecologists were satisfied with the cosmetic appearance of the genitalia. However, forty percent of these females experienced sexuality-related distress and 66% was at risk for developing a sexual dysfunction, whether they had surgery or not. Recognizing the difficulty of accurate assessment, our data indicate that feminizing surgery does not seem to improve nor hamper psychosexual outcome, especially in patients with severe virilization

    Predictors of self-perceived cultural responsiveness in entry-level physiotherapy students in Australia and Aotearoa New Zealand

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    Background: Ensuring physiotherapy students are well prepared to work safely and effectively in culturally diverse societies upon graduation is vital. Therefore, determining whether physiotherapy programs are effectively developing the cultural responsiveness of students is essential. This study aimed to evaluate the level of self-perceived cultural responsiveness of entry level physiotherapy students during their training, and explore the factors that might be associated with these levels. Methods: A cross sectional study of physiotherapy students from nine universities across Australia and Aotearoa New Zealand was conducted using an online self-administered questionnaire containing three parts: The Cultural Competence Assessment tool, Altemeyer’s Dogmatism scale, and the Marlowe-Crowne social desirability scale- short form. Demographic data relating to university, program, and level of study were also collected. Data was analysed using one-way ANOVA, t-tests and multiple regression analysis. Results: A total of 817 (19% response rate) students participated in this study. Overall, students had a moderate level of self-perceived cultural responsiveness (Mean (SD) = 5.15 (0.67)). Fewer number of weeks of clinical placement attended, lower levels of dogmatism, and greater social desirability were related to greater self-perceived cultural responsiveness. Additionally, fourth year undergraduate students perceived themselves to be less culturally responsive than first and second year students (p < 0.05). Conclusions: These results provide educators with knowledge about the level of self-perceived cultural responsiveness in physiotherapy students, and the factors that may need to be assessed and addressed to support the development of culturally responsive practice

    Virilization Due to Androgen Hypersecretion in a Patient with Ovarian Leydig Cell Tumor: Diagnostic and Psychosocial Implications

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    Virilisasi akibat kelebihan hormon androgen yang terjadi pada wanita akan menimbulkan tanda-tanda seperti pembesaran klitoris, perubahan suara, tumbuhnya rambut di wajah dan tubuh yang menjadi ciri khas laki-laki. Virilisasi yang disebabkan oleh tumor ovarium tidak lebih dari 0,5% dari seluruh penyebab. Kami melaporkan kasus virilisasi akibat tumor sel Leydig pada ovarium kiri wanita usia 36 tahun. Kesalahan interpretasi, informasi medis yang saling bertentangan dan saran dari dokter sebelumnya membuat kebingungan dari pasien tersebut. Kami melakukan evaluasi diagnostik yang meliputi gambaran klinik, hormon, pencitraan, pemeriksaan patologi, molekuler serta pemeriksaan psikologi. Pemeriksaan hormon menunjukkan kadar testosteron yang sangat tinggi. Adanya tumor pada ovarium terdeteksi dari pemeriksaan laparoskopi. Biopsi pada ovarium kiri dilakukan oleh karena pasien menolak dilakukan pengangkatan ovarium. Hasil pemeriksaan patologi menunjukkan tumor sel Leydig tanpa adanya tanda keganasan. Pengelolaan menjadi kurang optimal karena faktor sosial budaya yang menghambat walaupun telah dilakukan konseling secara mendalam. Tumor sel Leydig pada ovarium dicurigai apabila terjadi virilisasi pada wanita usia reproduktif disertai peningkatan hormon androgen, massa ovarium pada pemeriksaan pencitraan dan dibuktikan dengan hasil biopsi. Hal ini penting sebelum memberikan saran maupun pengobatan kepada pasien. Kata kunci: diagnostik work up, virilisasi, sel tumor Leydig. ABSTRACT Virilization due to hyperandrogenism in women causes male signs and symptoms such as swelling of the clitoris, deepening of the voice, facial hair and increase in body hair. Virilization is caused by less than 0.5% of all ovarian tumors. Here we report a case of virilizing Leydig cell tumor of the left ovary in a 36 year old woman. Misinterpretation of symptoms, conflicting medical information and advice from previous doctors had confused the patient. We performed a diagnostic evaluation including clinical, hormonal parameters, imaging, anatomical pathology examinations, and psychological assessment. Blood analysis showed a high testosterone level. The presence of an ovarian tumor was confirmed by laparoscopy. Since the patient refused ovariectomy, a biopsy of the left ovary was performed. Pathology showed a Leydig cell tumor without histological signs of malignancy. In spite of extensive explanation and psychological counseling, cultural barriers prevented appropriate treatment. An ovarian Leydig cell tumor should always be considered for a woman in the reproductive age with symptoms of virilization. The diagnosis is suspected on the basis of an ovarian mass on examination and further investigation and should be proven by biopsy. Key words: diagnostic work up, virilization, Leydig cell tumor

    Dynamics of Antibody and T Cell Immunity against SARS-CoV-2 Variants of Concern and the Impact of Booster Vaccinations in Previously Infected and Infection-Naïve Individuals

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    Despite previous coronavirus disease 2019 (COVID-19) vaccinations and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections, SARS-CoV-2 still causes a substantial number of infections due to the waning of immunity and the emergence of new variants. Here, we assessed the SARS-CoV-2 spike subunit 1 (S1)-specific T cell responses, anti-SARS-CoV-2 receptor-binding domain (RBD) IgG serum concentrations, and the neutralizing activity of serum antibodies before and one, four, and seven months after the BNT162b2 or mRNA-1273 booster vaccination in a cohort of previously infected and infection-naïve healthcare workers (HCWs). Additionally, we assessed T cell responses against the spike protein of the SARS-CoV-2 Delta, Omicron BA.1 and BA.2 variants of concern (VOC). We found that S1-specific T cell responses, anti-RBD IgG concentrations, and neutralizing activity significantly increased one month after booster vaccination. Four months after booster vaccination, T cell and antibody responses significantly decreased but levels remained steady thereafter until seven months after booster vaccination. After a similar number of vaccinations, previously infected individuals had significantly higher S1-specific T cell, anti-RBD IgG, and neutralizing IgG responses than infection-naïve HCWs. Strikingly, we observed overall cross-reactive T cell responses against different SARS-CoV-2 VOC in both previously infected and infection-naïve HCWs. In summary, COVID-19 booster vaccinations induce strong T cell and neutralizing antibody responses and the presence of T cell responses against SARS-CoV-2 VOC suggest that vaccine-induced T cell immunity offers cross-reactive protection against different VOC
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