Raman scattering owing to magneto-polaron states in monolayer transition metal dichalcogenides.

Magneto-optical measurements are fundamental research tools that allow for studying the hitherto unexplored optical transitions and the related applications of topological two-dimensional (2D) transition metal dichalcogenides (TMDs). A theoretical model is developed for the first-order magneto-resonant Raman scattering in a monolayer of TMD. A significant number of avoided crossing points involving optical phonons in the magneto-polaron (MP) spectrum, a superposition of the electron and hole states in the excitation branches, and their manifestations in optical transitions at various light scattering configurations are unique features for these 2D structures. The Raman intensity reveals three resonant splittings of double avoided-crossing levels. The three excitation branches are present in the MP spectrum provoked by the coupling of the Landau levels in the conduction and valence bands via an out-of-plane A 1 -optical phonon mode. The energy gaps at the anticrossing points in the MP scattering spectrum are revealed as a function of the electron and hole optical deformation potential constants. The resonant MP Raman scattering efficiency profile allows for quantifying the relative contribution of the conduction and valence bands in the formation of MPs. The results obtained are a guideline for controlling MP effects on the magneto-optical properties of TMD semiconductors, which open pathways to novel optoelectronic devices based on 2D TMDs.

Lattice vibration modes and electron-phonon interactions in monolayer vs. bilayer of transition metal dichalcogenides.

Transition metal dichalcogenides are at the center of intense scientific activity due to their promising applications, as well as the growing interest in basic research related to their electronic and dielectric properties. The layered structure of single-(ML) and two-layer (2ML) samples presents exciting features for light-matter interaction, electron transport, and electronic and optoelectronic applications. Lattice vibrations and electron-phonon interactions are essential for studying the above mentioned topics. Phonon spectra in ML and 2ML of MoX2 and WX2 (X = S, Se, and Te) families are studied using first principles calculations. A comprehensive analysis of the two-dimensional optical-phonon dispersion laws is performed, and the results illustrate the main differences between ML and 2ML for each considered semiconductor. Taking advantage of ab initio calculations, a generalization of the phenomenological Born-Huang dielectric model for long-wavelength vibrational modes around the Γ-point of the Brillouin zone (BZ) in 2ML structures is implemented. Explicit expressions are derived for the optical phonon dispersion of in-plane and out-of-plane normal modes. The set of characteristic parameters describing each long-wavelength optical branch is resolved from a direct comparison with the exact dispersion laws provided using the first principles calculations. The long-range electron-phonon Pekar-Fröhlich (PF) interaction and intra-valley electron scattering rates at the K-point of the BZ via E' (LO) and Eul longitudinal optical oscillations are examined for the ML and 2ML structures, respectively. The non-local macroscopic screening and the coupling between the in-plane electric field and longitudinal optical mechanical oscillation, profoundly affect the PF Hamiltonian and the carrier inverse relaxation time.

Risk factors for nosocomial COVID-19 in a French university hospital.

OBJECTIVES: Prevention strategies implemented by hospitals to reduce nosocomial transmission of SARS-CoV-2 sometimes failed. Our aim was to determine the risk factors for nosocomial COVID-19. PATIENTS AND METHODS: A case-control study was conducted (September 1, 2020-January 31, 2021) with adult patients hospitalized in medical or surgical units. Infants or patients hospitalized in ICU were excluded. Cases were patients with nosocomial COVID-19 (clinical symptoms and RT-PCR + for SARS-CoV-2 or RT-PCR + for SARS-CoV-2 with Ct ≤ 28 more than 5 days after admission); controls were patients without infection (RT-PCR- for SARS-CoV-2 > 5 days after admission). They were matched according to length of stay before diagnosis and period of admission. Analyses were performed with a conditional logistic regression. RESULTS: A total of 281 cases and 441 controls were included. In the bivariate analysis, cases were older (OR per 10 years: 1.22; 95%CI [1.10;1.36]), had more often shared a room (OR: 1.74; 95%CI [1.25;2.43]) or a risk factor for severe COVID-19 (OR: 1.94; 95%CI [1.09;3.45]), were more often hospitalized in medical units [OR: 1.59; 95%CI [1.12;2.25]), had higher exposure to contagious health care workers (HCW; OR per 1person-day: 1.12; 95%CI [1.08;1.17]) and patients (OR per 1 person-day: 1.11; 95%CI [1.08;1.14]) than controls. In an adjusted model, risk factors for nosocomial COVID-19 were exposure to contagious HCW (aOR per 1person-day: 1.08; 95%CI [1.03;1.14]) and to contagious patients (aOR per 1person-day: 1.10; 95%CI [1.07;1.13]). CONCLUSIONS: Exposure to contagious professionals and patients are the main risk factors for nosocomial COVID-19.

SARS-CoV-2 nosocomial infection acquired in a French university hospital during the 1st wave of the Covid-19 pandemic, a prospective study.

BACKGROUND: In healthcare facilities, nosocomial transmissions of respiratory viruses are a major issue. SARS-CoV-2 is not exempt from nosocomial transmission. Our goals were to describe COVID-19 nosocomial cases during the first pandemic wave among patients in a French university hospital and compliance with hygiene measures. METHODS: We conducted a prospective observational study in Grenoble Alpes University Hospital from 01/03/2020 to 11/05/2020. We included all hospitalised patients with a documented SARS-CoV-2 diagnosis. Nosocomial case was defined by a delay of 5 days between hospitalisation and first symptoms. Hygiene measures were evaluated between 11/05/2020 and 22/05/2020. Lockdown measures were effective in France on 17/03/2020 and ended on 11/05/2020. Systematic wearing of mask was mandatory for all healthcare workers (HCW) and visits were prohibited in our institution from 13/03/2021 and for the duration of the lockdown period. RESULTS: Among 259 patients included, 14 (5.4%) were considered as nosocomial COVID-19. Median time before symptom onset was 25 days (interquartile range: 12-42). Eleven patients (79%) had risk factors for severe COVID-19. Five died (36%) including 4 deaths attributable to COVID-19. Two clusters were identified. The first cluster had 5 cases including 3 nosocomial acquisitions and no tested HCWs were positive. The second cluster had 3 cases including 2 nosocomial cases and 4 HCWs were positive. Surgical mask wearing and hand hygiene compliance were adequate for 95% and 61% of HCWs, respectively. CONCLUSIONS: The number of nosocomial COVID-19 cases in our hospital was low. Compliance regarding mask wearing, hand hygiene and lockdown measures drastically reduced transmission of the virus. Monitoring of nosocomial COVID-19 cases during the first wave enabled us to determine to what extent the hygiene measures taken were effective and patients protected. Trial registration Study ethics approval was obtained retrospectively on 30 September 2020 (CECIC Rhône-Alpes-Auvergne, Clermont-Ferrand, IRB 5891).

Results of a multi-faceted educational intervention to prevent peripheral venous catheter-associated bloodstream infections.

Peripheral venous catheter-associated bloodstream infections (PVC-BSIs) lead to prolonged hospitalization, morbidity and increased costs. The impact of infection-prevention measures on the rate of PVC-BSIs in a university hospital in Spain was assessed. An active surveillance programme was initiated in 2015, which revealed a high PVC-BSI incidence ratio (0.48/1000 patient-days). A bundle aimed at nurses, medical staff and patients was implemented, and a Catheter Infection Team (CIT) was set up. The intervention achieved a decrease in PVC-BSI rate: 0.34 in 2016, 0.29 in 2017, and 0.17 in 2018. The decline was greatest for Gram-negative PVC-BSIs (67.6% in 2015, 35.3% in 2018).

Four Years' Experience in the Diagnosis of Very Long-Chain Acyl-CoA Dehydrogenase Deficiency in Infants Detected in Three Spanish Newborn Screening Centers.

Identification of very long-chain acyl-CoA dehydrogenase deficiency is possible in the expanded newborn screening (NBS) due to the increase in tetradecenoylcarnitine (C14:1) and in the C14:1/C2, C14:1/C16, C14:1/C12:1 ratios detected in dried blood spots. Nevertheless, different confirmatory tests must be performed to confirm the final diagnosis. We have revised the NBS results and the results of the confirmatory tests (plasma acylcarnitine profiles, molecular findings, and lymphocytes VLCAD activity) for 36 cases detected in three Spanish NBS centers during 4 years, correlating these with the clinical outcome and treatment. Our aim was to distinguish unambiguously true cases from disease carriers in order to obtain useful diagnostic information for clinicians that can be applied in the follow-up of neonates identified by NBS.Increases in C14:1 and of the different ratios, the presence of two pathogenic mutations, and deficient enzyme activity in lymphocytes (<12% of the intra-assay control) identified 12 true-positive cases. These cases were given nutritional therapy and all of them are asymptomatic, except one. Seventeen individuals were considered disease carriers based on the mild increase in plasma C14:1, in conjunction with the presence of only one mutation and/or intermediate residual activity (18-57%). In addition, seven cases were classified as false positives, with normal biochemical parameters and no mutations in the exonic region of ACADVL. All these carriers and the false positive cases remained asymptomatic. The combined evaluation of the acylcarnitine profiles, genetic results, and residual enzyme activities have proven useful to definitively classify individuals with suspected VLCAD deficiency into true-positive cases and carriers, and to decide which cases need treatment.

Quantum well electronic states in a tilted magnetic field.

We report the energy spectrum and the eigenstates of conduction and uncoupled valence bands of a quantum well under the influence of a tilted magnetic field. In the framework of the envelope approximation, we implement two analytical approaches to obtain the nontrivial solutions of the tilted magnetic field: (a) the Bubnov-Galerkin spectral method and b) the perturbation theory. We discuss the validity of each method for a broad range of magnetic field intensity and orientation as well as quantum well thickness. By estimating the accuracy of the perturbation method, we provide explicit analytical solutions for quantum wells in a tilted magnetic field configuration that can be employed to study several quantitative phenomena.

Bifidobacterium breve reduces apoptotic epithelial cell shedding in an exopolysaccharide and MyD88-dependent manner.

Certain members of the microbiota genus Bifidobacterium are known to positively influence host well-being. Importantly, reduced bifidobacterial levels are associated with inflammatory bowel disease (IBD) patients, who also have impaired epithelial barrier function, including elevated rates of apoptotic extrusion of small intestinal epithelial cells (IECs) from villi-a process termed 'cell shedding'. Using a mouse model of pathological cell shedding, we show that mice receiving Bifidobacterium breve UCC2003 exhibit significantly reduced rates of small IEC shedding. Bifidobacterial-induced protection appears to be mediated by a specific bifidobacterial surface exopolysaccharide and interactions with host MyD88 resulting in downregulation of intrinsic and extrinsic apoptotic responses to protect epithelial cells under highly inflammatory conditions. Our results reveal an important and previously undescribed role for B. breve, in positively modulating epithelial cell shedding outcomes via bacterial- and host-dependent factors, supporting the notion that manipulation of the microbiota affects intestinal disease outcomes.

Factors predicting distress among parents/caregivers of children with neurological disease and home enteral nutrition.

BACKGROUND & AIMS: Caregivers of children with chronic diseases included in a home enteral nutrition (HEN) programme are at risk of experiencing a feeling of burden, high level of anxiety and psychological distress. The aims of this study were: first, to examine the prevalence of symptoms of anxiety-depression in caregivers of children with neurological diseases requiring HEN by gastrostomy tube (GT); second, to compare the characteristics of caregivers with high or low risk of exhibiting symptoms of anxiety-depression; and third, to investigate possible associations to child disease severity and nutrition support mode. METHODS: A cross-sectional observational study was performed in 58 caregivers of children (31 boys, aged 0.3-18 years) with neurological diseases and GT feeding. The characteristics of caregivers with high or low risk of presenting symptoms of anxiety-depression were compared regarding the following variables: socio-demographic characteristics, the primary caregiver's intrapsychic factors, anthropometric parameters of the child, length of HEN, type of nutrients delivered by GT and infusion regime. RESULTS: All primary caregivers were mothers. Fifty-three per cent of them showed high risk of exhibiting symptoms of anxiety-depression. Mothers with high or low risk of presenting symptoms of anxiety-depression were comparable in age and family socio-economic status. They were also similar in terms of age, anthropometric conditions and length of HEN in their children.No differences were found between the two groups of mothers according to the level of the child's motor function impairment, type of nutrients delivered by GT and infusion regime. Higher levels of psychological distress and perception of burden overload were found in mothers with high risk of exhibiting symptoms of anxiety-depression. CONCLUSIONS: This study found a high prevalence of symptoms of anxiety-depression, perception of burden overload and psychological distress in caregivers of children with HEN. Thus, greater practical and emotional support is required for these families.

Analysis of the Spanish national registry for pediatric home enteral nutrition (NEPAD): implementation rates and observed trends during the past 8 years.

BACKGROUND/OBJECTIVES: The home enteral nutrition (HEN) provides nutritional support to children with chronic diseases who are nutritionally compromised and allows them to be discharged more quickly from hospitals. In 2003, a web-based registry (Nutrición Enteral Pediátrica Ambulatoria y Domiciliaria, Pediatric Ambulatory and Home Enteral Nutrition -NEPAD-) was created with the objective of gathering information about pediatric HEN practices in Spain. AIM: The aim of this study was to report the implementation of the NEPAD (Nutrición Enteral Pediátrica Ambulatoria y Domiciliaria, Pediatric Ambulatory and Home Enteral Nutrition) registry of pediatric HEN in Spain and to analyze data evolution trends from 2003 to 2010. SUBJECTS/METHODS: The data from the Spanish NEPAD registry were analyzed according to the following variables: demographic data, diagnosis, indication for HEN, nutritional support regime and administration route. RESULTS: Over the study period, 952 patients (1048 episodes) from 20 Spanish hospitals were included in the NEPAD registry. The most frequent indication for HEN was decreased oral intake (64%), and neurological disease was the most prevalent illness. HEN was delivered via a nasogastric tube in 573 episodes (54.7%), by gastrostomy in 375 episodes (35.8%), oral feeding in 77 episodes (7.3%) and by jejunal access in 23 episodes (2.2%). Significant differences in the mode of administration were observed based on the pathology of the child (χ(2), P<0.0001). The cyclic feeding was the most widely used technique for the administration of HEN. Most of the patients used a pump and a polymeric formula. Transition to oral feeding was the primary reason for discontinuation of this type of support. CONCLUSIONS: Since the NEPAD registry was established in Spain, the number of documented patients has increased more than 25-fold. Many children with chronic illness benefit from HEN, mainly those suffering from neurological diseases.

Psychometric properties of the structured Satisfaction Questionnaire with Gastrostomy Feeding (SAGA-8) for caregivers of children with gastrostomy tube nutritional support.

BACKGROUND: To analyse the psychometric properties of the structured Satisfaction Questionnaire with Gastrostomy Feeding (SAGA-8) in parents/caregivers of children with home enteral nutrition (HEN) by gastrostomy tube (GT). METHODS: Eighty-six caregivers (mothers) of paediatric patients with HEN by GT were recruited. Patients suffered from neurological disease (61.6%) and other chronic diseases. The SAGA-8 scale, a structured questionnaire to explore satisfaction with HEN by GT, and the Caregiver Burden Inventory (Zarit) were completed. The discriminating power of each of the SAGA-8 items, internal consistency and external validity were evaluated. An exploratory factor analysis and Kaiser-Meyer-Olkin (KMO) was performed as well. RESULTS: Eighty-four percent of the families expressed high satisfaction with GT feeding. All eight items of SAGA-8 gave additional information. The exploratory factor analysis revealed that a significant part of the items' variability could be explained by two independent factors: Factor 1 (direct benefit), which compiled the variables related to the perception of children's overall improvement by GT feeding; Factor 2 (indirect benefit), which grouped the variables related to a decrease in respiratory infections, feeding time and institutional support. Results from KMO (0.628) indicated the high adequacy of the items assessed in the factorial analysis. Moreover, the questionnaire presented high internal consistency (0.76), and the external validation analysis confirmed the correlation between SAGA-8 and Zarit, thereby emphasising the approptiate use of the SAGA-8 to detect carers' satisfaction. CONCLUSIONS: The SAGA-8 questionnaire has a high discriminatory power to assess the degree of satisfaction experienced by parents/caregivers of children with HEN by GT and, subsequently, the patients' wellbeing.

Temperature-dependent Raman study of thermal parameters in CdS quantum dots.

We report on the strong temperature-dependent thermal expansion, α(D), in CdS quantum dots (QDs) embedded in a glass template. We have performed a systematic study by using the temperature-dependent first-order Raman spectra, in CdS bulk and in dot samples, in order to assess the size dependence of α(D), and where the role of the compressive strain provoked by the glass host matrix on the dot response is discussed. We report the Grüneisen mode parameters and the anharmonic coupling constants for small CdS dots with mean radius R âˆ¼ 2.0 nm. We found that γ parameters change, with respect to the bulk CdS, in a range between 20 and 50%, while the anharmonicity contribution from two-phonon decay channel becomes the most important process to the temperature-shift properties.

[Epidemiological study of the metabolic diseases with homocystinuria in Spain]. / Estudio epidemiológico de las enfermedades metabólicas con homocistinuria en España.

OBJECTIVES: To determine the prevalence of homocystinuria in Spain and to establish the measures and mechanisms to ensure its prevention, diagnosis and treatment. MATERIAL AND METHODS: A national cross-sectional survey was conducted by means of a questionnaire sent to 35 hospitals in which children and adult patients are treated. RESULTS: Using the questionnaires submitted by 25 physicians from 16 centres, 75 patients were identified: 41 transsulphuration defects (one deceased), 27 remethylation (six deaths) and 7 without a syndromic diagnosis. The age at diagnosis varied widely, and 18 cases had more than one sibling affected. The more severe clinical manifestations involved the patients with remethylation defects. There was a high percentage of cognitive impairment, followed by lens diseases. Almost half of the patients had neurological disorders. There was increased vascular involvement in CBS-deficient adults. The therapeutic options most used were, folic acid, hydroxycobalamin and betaine. CONCLUSIONS: In view of these results and especially the small number of CBS deficiencies detected, we conclude that there is a need to introduce newborn screening for classical homocystinuria and ensure implementation of an appropriate diagnostic workup in all patients at risk.

[Herpes hepatic failure during the third quarter of pregnancy]. / Le cas clinique du mois. Hépatite herpétique au 3eme trimestre de la grossesse.

Acute liver diseases of pregnancy are common and usually transient and reversible. Given the number of different possible diagnoses, performing a large biological screening and a proper iconographic documentation is key. It makes sure no etiology fatal to the mother and her fetus is missed.

Home enteral nutrition in children: a 10 year experience with 304 pediatric patients.

BACKGROUND & AIMS: Home enteral nutrition is used increasingly in pediatric populations. Our objective was to describe the profile of pediatric patients requiring this treatment. MATERIAL AND METHODS: All patients under 18 years old requiring treatment with home enteral nutrition between January 1995 and December 2004 were analyzed retrospectively. RESULTS: 304 patients were studied (157 boys). The mean age at the start of treatment was 4.02 ± 4.09 years, median of 2.5 years; 28% of all patients were under 1 year. The main indications were oncological disease in 91 patients (29.9%) and digestive diseases in 84 (27.6%). There were significant differences depending on the clinical diagnosis for the start age, type of access, infusion regime and formula prescribed. Nutrients were delivered by nasogastric tube in 218 patients (71.7%). Overnight enteral nutrition was the preferred infusion regime in 155 patients (51%). Adult or pediatric polymeric formulas were mostly prescribed in 190 patients (62.5%). The mean treatment duration was 306 ± 544 days. CONCLUSION: In our series, enteral support usually begins at an early age. Its characteristics varied depending on patient pathology. Knowledge of the pediatric patient profile is important to design the most effective strategy for home enteral nutrition.

Consensus on paediatric enteral nutrition access: a document approved by SENPE/SEGHNP/ANECIPN/SECP.

Standardization of clinical procedures has become a desirable objective in contemporary medical practice. To this effect, the Spanish Society of Parenteral and Enteral Nutrition (SENPE) has endeavoured to create clinical practice guidelines and/or documents of consensus as well as quality standards in artificial nutrition. As a result, the SENPE´s Standardization Team has put together the "Document of Consensus in Enteral Access for Paediatric Nutritional Support" supported by the Spanish Society of Pediatric Gastroenterology, Hepatology and Nutrition (SEGHNP), the National Association of Pediatric and Neonatal Intensive Care Nursery (ANECIPN), and the Spanish Society of Pediatric Surgery (SECP). The present publication is a reduced version of our work; the complete document will be published as a monographic issue. It analyzes enteral access options in the pediatric patient, reviews the levels of evidence and provides the team-members' experience. Similarly, it details general and specific indications for pediatric enteral support, current techniques, care guidelines, methods of administration and complications of each enteral access. The data published by the American Society for Parenteral and Enteral Nutrition (ASPEN) and several European Societies has also been incorporated.

Anisotropic Confinement, Electronic Coupling and Strain Induced Effects Detected by Valence-Band Anisotropy in Self-Assembled Quantum Dots.

A method to determine the effects of the geometry and lateral ordering on the electronic properties of an array of one-dimensional self-assembled quantum dots is discussed. A model that takes into account the valence-band anisotropic effective masses and strain effects must be used to describe the behavior of the photoluminescence emission, proposed as a clean tool for the characterization of dot anisotropy and/or inter-dot coupling. Under special growth conditions, such as substrate temperature and Arsenic background, 1D chains of In0.4Ga0.6 As quantum dots were grown by molecular beam epitaxy. Grazing-incidence X-ray diffraction measurements directly evidence the strong strain anisotropy due to the formation of quantum dot chains, probed by polarization-resolved low-temperature photoluminescence. The results are in fair good agreement with the proposed model.