Comparison of life experiences of men and women in the sciences

A lack of sense of belonging and stereotype threat have been shown to contribute to women leaving the sciences (Seymour, 1997; Beasley & Fischer, 2012; Deemer et al., 2013). Contributing to this is the fact that most women find affirmation externally (through friends, family and professors) for their life decisions (Seymour, 1997; Zeldin, 2000). A set of comparative studies in 2000 and 2008 were done examining factors affecting women’s and men’s choices of majors and careers (Zeldin, 2000 and Zeldin, 2008). These studies concluded that men relied on achievements in science as the source of their career decisions to enter science, while women rely on social influences to enter and stay in science fields (Zeldin, 2008). However, the participants in Zeldin’s studies were well established in their science careers. In order to get a wider perspective of the decision-making process that scientists go through, scientists from a range of career decision making points need to be studied. Additionally, Zeldin’s study did not address scientists in academia. This qualitative study attempts to find common and dissimilar traits between men and women in the academic sciences in hopes of determining why they chose and persevered in a science related career. This study focused on the life experiences of men and women in science fields. Participants ranged in age from undergraduates pursuing a science related undergraduate degree to people who have retired from an academic career in the sciences. Participants completed personal statements and in-depth interviews which explored past choices as well as current perceptions of the results of those choices. Results and conclusions from both male and female participants will be discussed

Photostability of organic semiconductors : from bulk to nanoscales

Organic semiconductors have attracted considerable attention due to their applications in low-cost, solution-processable (opto)electronic devices. An important class of high-performance organic semiconductors is pentacene derivatives, which exhibit high charger carrier mobilities in field-effect transistors and ultrafast singlet fission in photovoltaic devices. These derivatives have served as benchmark materials for systematic studies of exciton and charge carrier dynamics, and they are the focus of this thesis. Photo-induced degradation of organic semiconductors is one of the bottlenecks preventing their wide-spread use in optoelectronic devices. As such, it is important to understand the underlying processes and develop strategies for their mitigation. For functionalized pentacene (Pn) two photodegradation processes are known to dominate: endoperoxide formation (EPO), which occurs in the presence of oxygen, and photodimerization, which occurs regardless of the presence of oxygen. The rate of decay is dependent on the specific Pn derivative and the local environment. This work explores the effects of environmental factors and specific molecular characteristics that affect the photostability and photodegradation reversibility of functionalized fluorinated pentacene (Pn-R-F8) derivatives, where R is a variable side group, and their non-fluorinated counterparts (Pn-R). Experiments are done in solutions and in films, from the bulk level (typically utilized in optoelectronic devices) to the single molecule level. In solutions, degradation of Pn molecules (monitored via changes in optical absorption under continuous illumination in air) and their partial recovery after thermolysis were quantified for various derivatives depending on the solvent, Pn concentration, side group (R), and fluorination. Fluorinated molecules (Pn-R-F8) were more stable than their non-fluorinated counterparts (Pn-R) and larger side groups (R) also protected the molecule from degradation. More concentrated solutions were considerably more stable as compared to dilute solutions. The nature of the solvent was also a factor; for example, molecules in chlorobenzene decay much faster than those in benzene under the same illumination conditions. The freshly made and photobleached solutions were analyzed using nuclear magnetic resonance (NMR) to identify the types of products formed. NMR spectra enabled identifi�cation of multiple products indicating that both EPO formation and dimerization are occurring simultaneously. In guest-host polymer films, where Pn molecules (guests) were dispersed at various concentrations in a host polymer, the photo-degradation was measured using photoluminescene spectroscopy (PL). In agreement with the experiments from solution, the thin-films showed that polymer host had a significant impact on photostability of Pn in films. For example, for the same concentration of Pn molecules, the films with a polymethylmethacrylate (PMMA) host exhibited considerably slower photodegradation as compared to those with the polyvinylidene fluoride (PVDF) host. Furthermore, an improvement in photostability was observed on the photodegradation and recovery rates when Pn is functionalized with the side group TCHS, than when using the side group TIPS. The effects of temperature of the samples were also measured using thin-film PL. Thermally activated behavior for the photodegradation processes was observed, with faster decay at higher temperatures as the added energy acted as a catalyst for the photo-decay reactions. However, added energy did not increase the amount of PL recovery in the samples until the temperature reached a high enough threshold, which in this case is between 350-370 K. The last parameter tested was concentration of Pn in films. At higher concentrations, the rate of photo-decay decreased, which indicates that in aggregate, the molecules are more protected from the causes of photo-degradation as compared to isolated molecules. The enhanced protection is enabled by concentration-dependent changes in the excited state dynamics and associated populations of reactive states. In order to understand and isolate the photodegradation processes on the molecular level, studies were performed on guest-host films with ultra-low concentrations of the Pn guest molecules. The Pn molecules were imaged in a variety of polymer matrices at 633 nm excitation at room temperature in air using wide-field fluorescence microscopy. Fluorescence time trajectories were collected and statistically analyzed to quantify blinking due to reversible EPO formation depending on the host matrix. This was also compared to single Pn donor (D) molecules that were imaged in PMMA in the presence of acceptor (A) molecules at various concentra�tions, which modified the local environment. Both changes to nanoenvironment affected the fluorescence of the molecules. For example, the PMMA host promoted the photostability of Pn molecules as compared to other polymer hosts studied, whereas addition of acceptor molecules reduced the photostability of the Pn donor molecules. To understand the physical changes of the molecular system, a Monte Carlo method was used to create a multi-level simulation, which enabled us to relate the change in the molecular transition rates to the experimentally measured parame�ters in our single-molecule fluorescence spectroscopy experiments. These compre�hensive studies provide insight into the synergistic effect of the local environment and molecular characteristics on the photodegradation and subsequent recovery of functionalized pentacene, which is important for development of next-generation materials with enhanced stability for organic electronic devices

Effect of Molecular Side Groups and Local Nanoenvironment on Photodegradation and Its Reversibility

Degradation of organic semiconductors in the presence of oxygen is one of the bottlenecks preventing their wide-spread use in optoelectronic devices. The first step towards such degradation in functionalized pentacene (Pn) derivatives is formation of endoperoxide (EPO), which can either revert back to the parent molecule or proceed to molecule decomposition. We present the study of reversibility of EPO formation through probing the photophysical properties of functionalized fluorinated pentacene (Pn-R-F8) derivatives. Experiments are done in solutions and in films both at the single molecule level and in the bulk. In solutions, degradation of optical absorption and its partial recovery after thermolysis were quantified for various derivatives depending on the solvent. At the single molecule level, low concentrations of each type of molecules were imaged in a variety of polymer matrices at 633 nm excitation at room temperature in air using wide-field fluorescence microscopy. Fluorescence time trajectories were collected and statistically analyzed to quantify blinking due to reversible EPO formation depending on the host matrix. To understand the physical changes of the molecular system, a Monte Carlo method was used to create a multi-level simulation, which enabled us to relate the change in the molecular transition rates to the experimentally measured parameters. At the bulk level, photoluminescence decay due to photobleaching and recovery due to EPO reconversion were measured for the same derivatives incorporated into various matrices. These studies provide insight into the synergistic effect of the local nanoenvironment and molecular side groups on the oxygen-related degradation and subsequent recovery which is important for development of organic electronic devices

Single Molecule-Level Study of Donor-Acceptor Interactions and Nanoscale Environment in Blends

Organic semiconductors have attracted considerable attention due to their applications in low-cost (opto)electronic devices. The most successful organic materials for applications that rely on charge carrier generation, such as solar cells, utilize blends of several types of molecules. In blends, the local environment strongly influences exciton and charge carrier dynamics. However, relationship between nanoscale features and photophysics is difficult to establish due to the lack of necessary spatial resolution. We use functionalized fluorinated pentacene (Pn) molecule as single molecule probes of intermolecular interactions and of the nanoscale environment in blends containing donor and acceptor molecules. Single Pn donor (D) molecules were imaged in PMMA in the presence of acceptor (A) molecules using wide-field fluorescence microscopy. Two sample configurations were realized: (i) a fixed concentration of Pn donor molecules, with increasing concentration of acceptor molecules (functionalized indenflouorene or PCBM) and (ii) a fixed concentration of acceptor molecules with an increased concentration of the Pn donor. The D-A energy transfer and changes in the donor emission due to those in the acceptor- modified polymer morphology were quantified. The increase in the acceptor concentration was accompanied by enhanced photobleaching and blinking of the Pn donor molecules. To better understand the underlying physics of these processes, we modeled photoexcited electron dynamics using Monte Carlo simulations. The simulated blinking dynamics were then compared to our experimental data, and the changes in the transition rates were related to the changes in the nanoscale environment. Our study provides insight into evolution of nanoscale environment during the formation of bulk heterojunctions

Reemergence of Syphilis in Martinique, 2001–2008

Syphilis reemerged in Martinique in 2004 and initially affected 3 HIV-infected patients. By March 2008, syphilis was diagnosed for 37 men and 18 women. As of October 31, 2009, this outbreak had not yet been brought under control. It initially affected mainly men who had sex with men before it spread to heterosexual persons, minority group members, and crack cocaine users

Dupilumab but not cyclosporine treatment shifts the microbiome toward a healthy skin flora in patients with moderate‐to‐severe atopic dermatitis

Background: Atopic dermatitis (AD) patients display an altered skin microbiome which may not only be an indicator but also a driver of inflammation. We aimed to investigate associations among AD patients' skin microbiome, clinical data, and response to systemic therapy in patients of the TREATgermany registry. Methods: Skin swabs of 157 patients were profiled with 16S rRNA gene amplicon sequencing before and after 3 months of treatment with dupilumab or cyclosporine. For comparison, 16s microbiome data from 258 population-based healthy controls were used. Disease severity was assessed using established instruments such as the Eczema Area and Severity Index (EASI). Results: We confirmed the previously shown correlation of Staphylococcus aureus abundance and bacterial alpha diversity with AD severity as measured by EASI. Therapy with Dupilumab shifted the bacterial community toward the pattern seen in healthy controls. The relative abundance of Staphylococci and in particular S. aureus significantly decreased on both lesional and non-lesional skin, whereas the abundance of Staphylococcus hominis increased. These changes were largely independent from the degree of clinical improvement and were not observed for cyclosporine. Conclusions: Systemic treatment with dupilumab but not cyclosporine tends to restore a healthy skin microbiome largely independent of the clinical response indicating potential effects of IL-4RA blockade on the microbiome

COVID-19 symptoms at hospital admission vary with age and sex: results from the ISARIC prospective multinational observational study

Background: The ISARIC prospective multinational observational study is the largest cohort of hospitalized patients with COVID-19. We present relationships of age, sex, and nationality to presenting symptoms. Methods: International, prospective observational study of 60 109 hospitalized symptomatic patients with laboratory-confirmed COVID-19 recruited from 43 countries between 30 January and 3 August 2020. Logistic regression was performed to evaluate relationships of age and sex to published COVID-19 case definitions and the most commonly reported symptoms. Results: ‘Typical’ symptoms of fever (69%), cough (68%) and shortness of breath (66%) were the most commonly reported. 92% of patients experienced at least one of these. Prevalence of typical symptoms was greatest in 30- to 60-year-olds (respectively 80, 79, 69%; at least one 95%). They were reported less frequently in children (≤ 18 years: 69, 48, 23; 85%), older adults (≥ 70 years: 61, 62, 65; 90%), and women (66, 66, 64; 90%; vs. men 71, 70, 67; 93%, each P < 0.001). The most common atypical presentations under 60 years of age were nausea and vomiting and abdominal pain, and over 60 years was confusion. Regression models showed significant differences in symptoms with sex, age and country. Interpretation: This international collaboration has allowed us to report reliable symptom data from the largest cohort of patients admitted to hospital with COVID-19. Adults over 60 and children admitted to hospital with COVID-19 are less likely to present with typical symptoms. Nausea and vomiting are common atypical presentations under 30 years. Confusion is a frequent atypical presentation of COVID-19 in adults over 60 years. Women are less likely to experience typical symptoms than men

n. sp. (Kinetoplastida: Trypanosomatidae), description of the parasite responsible for cutaneous leishmaniasis in Martinique Island (French West Indies)

The parasite responsible for autochthonous cutaneous leishmaniasis in Martinique island (French West Indies) was first isolated in 1995; its taxonomical position was established only in 2002, but it remained unnamed. In the present paper, the authors name this parasite Leishmania (Leishmania) martiniquensis Desbois, Pratlong & Dedet n. sp. and describe the type strain of this taxon, including its biological characteristics, biochemical and molecular identification, and pathogenicity. This parasite, clearly distinct from all other Euleishmania, and placed at the base of the Leishmania phylogenetic tree, is included in the subgenus Leishmania

Leishmania (Leishmania) martiniquensis n. sp. (Kinetoplastida: Trypanosomatidae), description of the parasite responsible for cutaneous leishmaniasis in Martinique Island (French West Indies)

The parasite responsible for autochthonous cutaneous leishmaniasis in Martinique island (French West Indies) was first isolated in 1995; its taxonomical position was established only in 2002, but it remained unnamed. In the present paper, the authors name this parasite Leishmania (Leishmania) martiniquensis Desbois, Pratlong & Dedet n. sp. and describe the type strain of this taxon, including its biological characteristics, biochemical and molecular identification, and pathogenicity. This parasite, clearly distinct from all other Euleishmania, and placed at the base of the Leishmania phylogenetic tree, is included in the subgenus Leishmania