Mechanisms of refractive index modification during femtosecond laser writing of waveguides in alkaline lead-oxide silicate glass

3 pages, 3 figures.We report on the mechanisms responsible for the formation of optical waveguides upon femtosecond laser irradiation of an alkaline lead-oxide silicate glass. MicroRaman spectroscopy and nonlinear fluorescence were employed to probe the local glass network structure and the formation of optically active defects respectively. At low laser pulse energies, the laser modified region is formed by a single light guiding region, whereas for pulses above 14 µJ the modified region is formed by a central dark zone, which does not guide light, accompanied by light guiding zones located in the surrounding of the dark one. This behavior is different from that observed in common silica glass systems but agrees with recent results obtained in phosphate and heavy metal oxide glasses. However, our results show that, unlike the latter glass, local densification of the glass occurs in the whole laser modified region, i.e., in the dark and the guiding zones. The suppression of light guiding in the dark region is explained by a high density of absorbing color centers.This work was partially supported by CICYT (Spain) under Project No. DPI2002-00151. One of the authors (V.D.B.) acknowledges the financial support of the CSIC and the European Social Fund through an I3P Ph.D. fellowship. Another author (P.L.-A. acknowledges funding from the Spanish Government ( the Ramón y Cajal program and Grant No. TIC2003-07485).Peer reviewe

Anisotropic Laser-Pulse-Induced Magnetization Dynamics in van der Waals Magnet Fe3_3GeTe2_2

Femtosecond laser-pulse excitation provides an energy efficient and fast way to control magnetization at the nanoscale, providing great potential for ultrafast next-generation data manipulation and nonvolatile storage devices. Ferromagnetic van der Waals materials have garnered much attention over the past few years due to their low dimensionality, excellent magnetic properties, and large response to external stimuli. Nonetheless, their behaviour upon fs laser-pulse excitation remains largely unexplored. Here, we investigate the ultrafast magnetization dynamics of a thin flake of Fe3GeTe2 (FGT) and extract its intrinsic magnetic properties using a microscopic framework. We find that our data is well described by our modeling, with FGT undergoing a slow two-step demagnetization, and we experimentally extract the spin-relaxation timescale as a function of temperature, magnetic field and excitation fluence. Our observations indicate a large spin-flip probability in agreement with a theoretically expected large spin-orbit coupling, as well as a weak interlayer exchange coupling. The spin-flip probability is found to increase when the magnetization is pulled away from its quantization axis, opening doors to an external control over the spins in this material. Our results provide a deeper understanding of the dynamics van der Waals materials upon fs laser-pulse excitation, paving the way towards two-dimensional materials-based ultrafast spintronics

Extraction of Dzyaloshinksii-Moriya interaction from propagating spin waves validated

The interfacial Dzyaloshinksii-Moriya interaction (iDMI) is of great interest in thin-film magnetism because of its ability to stabilize chiral spin textures. It can be quantified by investigating the frequency non-reciprocity of oppositely propagating spin waves. However, as the iDMI is an interface interaction the relative effect reduces when the films become thicker making quantification more difficult. Here, we utilize all-electrical Propagating Spin Wave Spectroscopy (PSWS) to disentangle multiple contributions to spin wave frequency non-reciprocity to determine the iDMI. This is done by investigating non-reciprocities across a wide range of magnetic layer thicknesses (from 4 to 26 nm) in Pt/Co/Ir, Pt/Co/Pt, and Ir/Co/Pt stacks. We find the expected sign change in the iDMI when inverting the stack order, and a negligible iDMI for the symmetric Pt/Co/Pt. We additionally extract a difference in surface anisotropies and find a large contribution due to the formation of different crystalline phases of the Co, which is corroborated using nuclear magnetic resonance and high-resolution transmission-electron-microscopy measurements. These insights will open up new avenues to investigate, quantify and disentangle the fundamental mechanisms governing the iDMI, and pave a way towards engineered large spin-wave non-reciprocities for magnonic applications.Comment: 12 pages, 2 figure

Forecasting levels of serum 25-hydroxyvitamin D based on dietary intake, lifestyle and personal determinants in a sample of Southern Europeans

Vitamin D is an essential nutrient to be consumed in the habitual dietary intake, whose deficiency is associated with various disturbances. This study represents a validation of vitamin D status estimation using a semi-quantitative FFQ, together with data from additional physical activity and lifestyle questionnaires. This information was combined to forecast the serum vitamin D status. Different statistical methods were applied to estimate the vitamin D status using predictors based on diet and lifestyle. Serum vitamin D was predicted using linear regression (with leave-one-out cross-validation) and random forest models. Intraclass correlation coefficients, Lin’s agreement coefficients, Bland–Altman plots and other methods were used to assess the accuracy of the predicted v. observed serum values. Data were collected in Spain. A total of 220 healthy volunteers aged between 18 and 78 years were included in this study. They completed validated questionnaires and agreed to provide blood samples to measure serum 25-hydroxyvitamin D (25(OH)D) levels. The common final predictors in both models were age, sex, sunlight exposure, vitamin D dietary intake (as assessed by the FFQ), BMI, time spent walking, physical activity and skin reaction after sun exposure. The intraclass correlation coefficient for the prediction was 0·60 (95 % CI: 0·52, 0·67; P < 0·001) using the random forest model. The magnitude of the correlation was moderate, which means that our estimation could be useful in future epidemiological studies to establish a link between the predicted 25(OH)D values and the occurrence of several clinical outcomes in larger cohorts

Depression in internal medicine inpatients at the time of hospital discharge and referral to primary care

Background and objectives: This is the first multi-center study intended to document the prevalence, characteristics, and associations of depression in Medicine patients at the time of hospital discharge and their referral to Primary Care (PC). Methods: Adult patients randomly selected among consecutive admissions to Medicine wards in 8 hospitals in Spain, covering health districts, were examined in a two-phase ''case-finding'' procedure. Standardized, Spanish versions of instruments were used, including the Standardized Polyvalent Psychiatric Interview (SPPI) and Cumulative Illness Rating Scale (CIRS). Cases of depression were diagnosed according to ICD-10 general hospital research criteria. Results: Three hundred and twelve patients with treatable depression and 777 non-depressed controls were identified. In a conservative estimate, the global prevalence of major depression was 7.1%, dysthymia 4.2% and adjustment depression 7.1%, and 51.9% of cases were of moderate/ severe intensity. Depression was more frequent in women, the differences being significant in all categories of depression. The prevalence of depression was lower in individuals aged 85 or more years, the differences being significant in cases of both dysthymia and adjustment depression. A clear pattern of decreasing prevalence with age was observed in women. The depressed had as an average five medical systems affected, and higher CIRS scores compared with the controls, the differences being significant in cases of both major depression and dysthymia. Conclusions: This is the first report showing a considerable prevalence of treatable cases of depression in Medicine patients at the time of hospital discharge and referral to PC. Depression is associated with the severity of the medical condition, and differences observed by age and sex have clinical implications. Paper read at the 3rd Annual Meeting of the European Association of Psychosomatic Medicine, Nuremberg 2015. © 2022 Asociación Universitaria de Zaragoza para el Progreso de la Psiquiatría y la Salud Menta

Neutrophil count is associated with reduced gray matter and enlarged ventricles in first-episode psychosis

Although there is recent evidence that cells from the peripheral immune system can gain access to the central nervous system in certain conditions such as multiple sclerosis, their role has not been assessed in psychosis. Here, we aimed to explore whether blood cell count was associated with brain volume and/or clinical symptomatology. A total of 218 participants (137 first-episode psychosis patients [FEP] and 81 healthy controls [HC]) were included in the study. For each participant, a T1 structural image was acquired, from which brain tissue volumes were calculated. We found that, in FEP, neutrophil count was associated with reduced gray matter (GM) volume (ß = -0.117, P < .001) and increased cerebrospinal fluid volume (ß = 0.191, P = .007). No associations were observed in HC. GM reduction was generalized but more prominent in certain regions, notably the thalamus, the anterior insula, and the left Heschl''s gyrus, among many others. Neutrophil count was also associated with the total PANSS score (ß = 0.173, P = .038), including those items assessing hallucinations (ß = 0.182, P = .028) and avolition (ß = 0.197, P = .018). Several confounders, such as antipsychotic medication, body mass index, and smoking, were controlled for. Overall, the present study may represent the first indirect evidence of brain tissue loss associated with neutrophils in psychosis, and lends support to the hypothesis of a dysregulated immune system. Higher neutrophil count was also associated with more severe clinical symptomatology, which renders it a promising indicator of schizophrenia severity and could even give rise to new therapies

Impact of previous tobacco use with or without cannabis on first psychotic experiences in patients with first-episode psychosis

Objective: There is high prevalence of cigarette smoking in individuals with first-episode psychosis (FEP) prior to psychosis onset. The purpose of the study was to determine the impact of previous tobacco use with or without cannabis on first psychotic experiences in FEP and the impact of this use on age of onset of symptoms, including prodromes. Methods: Retrospective analyses from the naturalistic, longitudinal, multicentre, “Phenotype-Genotype and Environmental Interaction. Application of a Predictive Model in First Psychotic Episodes (PEPs)” Study. The authors analysed sociodemographic/clinical data of 284 FEP patients and 231 matched healthy controls, and evaluated first psychotic experiences of patients using the Symptom Onset in Schizophrenia Inventory. Results: FEP patients had significantly higher prevalence of tobacco, cannabis, and cocaine use than controls. The FEP group with tobacco use only prior to onset (N = 56) had more sleep disturbances (42.9% vs 18.8%, P = 0.003) and lower prevalence of negative symptoms, specifically social withdrawal (33.9% vs 58%, P = 0.007) than FEP with no substance use (N = 70), as well as lower prevalence of ideas of reference (80.4% vs 92.4%, P = 0.015), perceptual abnormalities (46.4% vs 67.4%, P = 0.006), hallucinations (55.4% vs 71.5%, P = 0.029), and disorganised thinking (41.1% vs 61.1%, P = 0.010) than FEP group with previous tobacco and cannabis use (N = 144). FEP patients with cannabis and tobacco use had lower age at first prodromal or psychotic symptom (mean = 23.73 years [SD = 5.09]) versus those with tobacco use only (mean = 26.21 [SD = 4.80]) (P = 0.011). Conclusions: The use of tobacco alone was not related to earlier age of onset of a first psychotic experience, but the clinical profile of FEP patients is different depending on previous tobacco use with or without cannabis. © 2021 The Author

Anisotropic Laser-Pulse-Induced Magnetization Dynamics in van der Waals Magnet Fe3_3GeTe2_2

Femtosecond laser-pulse excitation provides an energy efficient and fast way to control magnetization at the nanoscale, providing great potential for ultrafast next-generation data manipulation and nonvolatile storage devices. Ferromagnetic van der Waals materials have garnered much attention over the past few years due to their low dimensionality, excellent magnetic properties, and large response to external stimuli. Nonetheless, their behaviour upon fs laser-pulse excitation remains largely unexplored. Here, we investigate the ultrafast magnetization dynamics of a thin flake of Fe$_3$GeTe$_2$ (FGT) and extract its intrinsic magnetic properties using a microscopic framework. We find that our data is well described by our modelling, with FGT undergoing a slow two-step demagnetization, and we experimentally extract the spin-relaxation timescale as a function of temperature, magnetic field and excitation fluence. Our observations indicate a large spin-flip probability in agreement with a theoretically expected large spin-orbit coupling, as well as a weak interlayer exchange coupling. The spin-flip probability is found to increase when the magnetization is pulled away from its quantization axis, opening doors to an external control over the spins in this material. Our results provide a deeper understanding of the dynamics van der Waals materials upon fs laser-pulse excitation, paving the way towards two-dimensional materials-based ultrafast spintronics.Comment: Supplementary information include