Pulse duration dependent optical nonlinearities of Bi2Se3 thin films.

Topological insulators, such as the Bi2Se3 material, exhibit significant optical nonlinearities. This work investigates the impact of the pulse duration on the nonlinear optical responses of Bi2Se3 layers. Scanning electron microscopy studies have been performed to reveal the crystalline structure of the samples. The nonlinear optical performance has been investigated for a wide range of pulse durations, from 400 fs to 10 ps, using 1030 nm laser excitation. The nonlinear absorption coefficients recorded in this study range from -1.45 x10-7 m/W to -4.86 x10-7 m/W. The influence of two different mechanisms on optical nonlinearities was observed and discussed. Identical experimental conditions have been employed throughout the studies allowing a direct comparison of the results.

Achievement of appropriate cesarean rates using Robson's 10-Group classification system in Brazilian private practice.

BACKGROUND: Increasing cesarean section (CS) rates are a global concern because they are related to higher maternal and neonatal complication rates and do not provide positive childbirth experiences. In 2019, Brazil ranked second globally, given its overall CS rate of 57%. According to the World Health Organization (WHO), populational CS rates of 10-15% are associated with decreased maternal, neonatal, and infant mortality rates. This study aimed to investigate whether multidisciplinary care following evidence-based protocols associated with a high motivation of both women and professionals for a vaginal birth leads to less overuse of CS in a Brazilian private practice (PP). METHODS: This cross-sectional study evaluated CS rates by Robson group for women who sought vaginal birth in a private practice in Brazil comparing with Swedish data. Collaborative care of midwives and obstetricians who adopted evidence-based guidelines was offered. CS rates, overall and by Robson group, contribution of each Robson group to the overall CS rate, clinical and nonclinical interventions, vaginal birth, pre-labor CS, and intrapartum CS proportions were estimated. The expected CS rate was calculated using the World Health Organization C-model tool. The analysis used Microsoft Excel and R Studio (version 1.2.1335. 2009-2019). RESULTS: The PP overall CS rate was 15.1% (95%CI, 13.4-17.1%) versus the 19.8% (95%CI, 14.8-24.7%) rate expected by the WHO C-model tool. The population included 43.7% women in Robson Group 1 (nulliparous, single, cephalic, at term, spontaneous labor), 11.4% in Group 2 (nulliparous, single, cephalic, at term, induced labor or CS before labor), and 14.9% in Group 5 (multiparous women with previous CS), the greatest contributors to higher CS rates (75.4% of them). The Swedish overall CS rate was 17.9% (95%CI, 17.6-18.1%) in a population of 27% women in Robson Group 1, 10.7% in Group 2, and 9.2% in Group 5. CONCLUSIONS: Multidisciplinary care following evidence-based protocols, associated with high motivation of both women and professionals for vaginal birth, may lead to a significant and safe reduction of CS rates even in contexts such as Brazil, with high medicalization of obstetric care and excess CS.

Nanometer scale insight on the analysis of limpets mineralized teeth: Special focus on the silica-containing regions.

We report the electron microscopy-based analysis of the major lateral tooth of the limpet Colisella subrugosa during early and intermediate stages of development. We aimed to analyze the structural relationship among the needle-like crystals of the iron oxide goethite, the amorphous silica phase that forms the tooth base and occupy inter-crystalline spaces in the cusp, and the chitin fibers of the matrix. Goethite crystals followed the three dimensional organization pattern of the chitin fibers in the cusp. In the tooth base, spherical individual silica granules were found in regions where the chitin fibers cross. The spherical granules near the interface between the tooth base and the cusp (junction zone) formed an almost continuous medium that could easily be ultrathin-sectioned for further analysis. By contrast, the nearby silica-rich region localized on the other side of the junction zone contained needle-like goethite crystals immersed in the matrix and presented a conchoidal fracture. The chitin fibers from the silica granules of the tooth base were dotted or undulating in projection with a periodicity of about 6 nm when observed by high magnification transmission electron microscopy. Very thin goethite crystals were present in the base of the cusp near the junction zone surrounded by silica. On several occasions, crystals presented internal thin straight white lines parallel to the major axis, indicating a possible growth around fibers. We propose that silica and iron oxide phases mineralization may occur simultaneously at least for some period and that silica moderates the dimensions of the iron oxide crystals.

Patient Navigation to Improve Early Access to Supportive Care for Patients with Advanced Cancer in Resource-Limited Settings: A Randomized Controlled Trial.

BACKGROUND: The early integration of supportive care in oncology improves patient-centered outcomes. However, data are lacking regarding how to achieve this in resource-limited settings. We studied whether patient navigation increased access to multidisciplinary supportive care among Mexican patients with advanced cancer. MATERIALS AND METHODS: This randomized controlled trial was conducted between August 2017 and April 2018 at a public hospital in Mexico City. Patients aged ≥18 years with metastatic tumors ≤6 weeks from diagnosis were randomized (1:1) to a patient navigation intervention or usual care. Patients randomized to patient navigation received personalized supportive care from a navigator and a multidisciplinary team. Patients randomized to usual care obtained supportive care referrals from treating oncologists. The primary outcome was the implementation of supportive care interventions at 12 weeks. Secondary outcomes included advance directive completion, supportive care needs, and quality of life. RESULTS: One hundred thirty-four patients were randomized: 67 to patient navigation and 67 to usual care. Supportive care interventions were provided to 74% of patients in the patient navigation arm versus 24% in usual care (difference 0.50, 95% confidence interval [CI] 0.34-0.62; p < .0001). In the patient navigation arm, 48% of eligible patients completed advance directives, compared with 0% in usual care (p < .0001). At 12 weeks, patients randomized to patient navigation had less moderate/severe pain (10% vs. 33%; difference 0.23, 95% CI 0.07-0.38; p = .006), without differences in quality of life between arms. CONCLUSION: Patient navigation improves access to early supportive care, advance care planning, and pain for patients with advanced cancer in resource-limited settings. IMPLICATIONS FOR PRACTICE: The early implementation of supportive care in oncology is recommended by international guidelines, but this might be difficult to achieve in resource-limited settings. This randomized clinical trial including 134 Mexican patients with advanced cancer demonstrates that a multidisciplinary patient navigation intervention can improve the early access to supportive and palliative care interventions, increase advance care planning, and reduce symptoms compared with usual oncologist-guided care alone. These results demonstrate that patient navigation represents a potentially useful solution to achieve the adequate implementation of supportive and palliative care in resource-limited settings globally.

Accurate and objective determination of myalgic encephalomyelitis/chronic fatigue syndrome disease severity with a wearable sensor.

BACKGROUND: Approximately 2.5 million people in the U.S. suffer from myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). This disease negatively impacts patients' ability to function, often resulting in difficulty maintaining employment, sustaining financial independence, engaging socially with others, and in particularly severe cases, consistently and adequately performing activities of daily living. The focus of this research was to develop a sensor-based method to measure upright activity defined as time with feet on the floor and referred to as UpTime, as an indicator of ME/CFS disease severity. METHODS: A commercially available inertial measurement unit (IMU), the Shimmer, was selected for this research. A Kalman filter was used to convert IMU data collected by the Shimmer to angle estimates. Angle estimate accuracy was confirmed by comparison to a motion capture system. Leg angle estimates were then converted to personalized daily UpTime scores using a critical angle of 39º from vertical to differentiate between upright (feet on the floor) and not upright. A 6-day, case-control study with 15 subjects (five healthy controls, five moderate-level ME/CFS, and five severe-level ME/CFS) was conducted to determine the utility of UpTime for assessing disease severity. RESULTS: UpTime was found to be a significant measure of ME/CFS disease severity. Severely ill ME/CFS patients spend less than 20% of each day with feet on the floor. Moderately ill ME/CFS patients spend between 20-30% of each day with feet on the floor. Healthy controls have greater than 30% UpTime. IMU-measured UpTime was more precise than self-reported hours of upright activity which were over-estimated by patients. CONCLUSIONS: UpTime is an accurate and objective measure of upright activity, a measure that can be used to assess disease severity in ME/CFS patients. Due to its ability to accurately monitor upright activity, UpTime can also be used as a reliable endpoint for evaluating ME/CFS treatment efficacy. Future studies with larger samples and extended data collection periods are required to fully confirm the use of UpTime as a measure of disease severity in ME/CFS. With the added perspective of large-scale studies, this sensor-based platform could provide a recovery path for individuals struggling with ME/CFS.

Hemodynamics during the 10-minute NASA Lean Test: evidence of circulatory decompensation in a subset of ME/CFS patients.

BACKGROUND: Lightheadedness, fatigue, weakness, heart palpitations, cognitive dysfunction, muscle pain, and exercise intolerance are some of the symptoms of orthostatic intolerance (OI). There is substantial comorbidity of OI in ME/CFS (Myalgic Encephalomyelitis/Chronic Fatigue Syndrome). The 10-minute NASA Lean Test (NLT) is a simple, point-of-care method that can aid ME/CFS diagnosis and guide management and treatment of OI. The objective of this study was to understand the hemodynamic changes that occur in ME/CFS patients during the 10-minute NLT. METHODS: A total of 150 ME/CFS patients and 75 age, gender and race matched healthy controls (HCs) were enrolled. We recruited 75 ME/CFS patients who had been sick for less than 4 years (< 4 ME/CFS) and 75 ME/CFS patients sick for more than 10 years (> 10 ME/CFS). The 10-minute NLT involves measurement of blood pressure and heart rate while resting supine and every minute for 10 min while standing with shoulder-blades on the wall for a relaxed stance. Spontaneously reported symptoms are recorded during the test. ANOVA and regression analysis were used to test for differences and relationships in hemodynamics, symptoms and upright activity between groups. RESULTS: At least 5 min of the 10-minute NLT were required to detect hemodynamic changes. The < 4 ME/CFS group had significantly higher heart rate and abnormally narrowed pulse pressure compared to > 10 ME/CFS and HCs. The < 4 ME/CFS group experienced significantly more OI symptoms compared to > 10 ME/CFS and HCs. The circulatory decompensation observed in the < 4 ME/CFS group was not related to age or medication use. CONCLUSIONS: Circulatory decompensation characterized by increased heart rate and abnormally narrow pulse pressure was identified in a subgroup of ME/CFS patients who have been sick for < 4 years. This suggests inadequate ventricular filling from low venous pressure. The 10-minute NLT can be used to diagnose and treat the circulatory decompensation in this newly recognized subgroup of ME/CFS patients. The > 10 ME/CFS group had less pronounced hemodynamic changes during the NLT possibly from adaptation and compensation that occurs over time. The 10-minute NLT is a simple and clinically useful point-of-care method that can be used for early diagnosis of ME/CFS and help guide OI treatment.

Physiotherapeutic Treatment for Levator Ani Avulsion after Delivery: A Transperineal Three-dimensional Ultrasound Assessment.

BACKGROUND: Levator ani avulsion is defined as the interruption of the insertion of this muscle on the pubic bone. It is currently recognized as an important triggering factor for genital prolapse. Although surgical interventions are available, there are no conservative strategies for this muscular injury. DESCRIPTION: A 40-year-old female presented with urinary incontinence and levator ani avulsion, which was confirmed on transperineal three-dimensional ultrasound (3DUS). Upon referral for physiotherapy, she presented with incorrect and weak contractions of the pelvic floor. Her treatment comprised 13 sessions of intravaginal electrotherapy followed by pelvic floor muscle (PFM) exercises in different positions. At the end of the sessions, another transperineal 3DUS was performed, and it revealed rapprochement of the levator ani muscle. The avulsed levator ani muscle can be reinserted using physiotherapeutic interventions, especially a combination of electrotherapy and PFM exercises. CONCLUSION: Transperineal 3DUS is an important approach for the follow-up of conservative treatment until full recovery.

Biomineralization of calcium carbonate in the cell wall of Lithothamnion crispatum (Hapalidiales, Rhodophyta): correlation between the organic matrix and the mineral phase.

Over the past few decades, progress has been made toward understanding the mechanisms of coralline algae mineralization. However, the relationship between the mineral phase and the organic matrix in coralline algae has not yet been thoroughly examined. The aim of this study was to describe the cell wall ultrastructure of Lithothamnion crispatum, a cosmopolitan rhodolith-forming coralline algal species collected near Salvador (Brazil), and examine the relationship between the organic matrix and the nucleation and growth/shape modulation of calcium carbonate crystals. A nanostructured pattern was observed in L. crispatum along the cell walls. At the nanoscale, the crystals from L. crispatum consisted of several single crystallites assembled and associated with organic material. The crystallites in the bulk of the cell wall had a high level of spatial organization. However, the crystals displayed cleavages in the (104) faces after ultrathin sectioning with a microtome. This organism is an important model for biomineralization studies as the crystallographic data do not fit in any of the general biomineralization processes described for other organisms. Biomineralization in L. crispatum is dependent on both the soluble and the insoluble organic matrix, which are involved in the control of mineral formation and organizational patterns through an organic matrix-mediated process. This knowledge concerning the mineral composition and organizational patterns of crystals within the cell walls should be taken into account in future studies of changing ocean conditions as they represent important factors influencing the physico-chemical interactions between rhodoliths and the environment in coralline reefs.

Strontium ranelate changes the composition and crystal structure of the biological bone-like apatite produced in osteoblast cell cultures.

We evaluate the effects of strontium ranelate on the composition and crystal structure of the biological bone-like apatite produced in osteoblast cell cultures, a system that gave us the advantage of obtaining mineral samples produced exclusively during treatment. Cells were treated with strontium ranelate at concentrations of 0.05 and 0.5 mM Sr(2+). Mineral substances were isolated and analyzed by using a combination of methods: Fourier transform infrared spectroscopy, solid-state (1)H nuclear magnetic resonance, X-ray diffraction, micro-Raman spectroscopy and energy dispersive X-ray spectroscopy. The minerals produced in all cell cultures were typical bone-like apatites. No changes occurred in the local structural order or crystal size of the minerals. However, we noticed several relevant changes in the mineral produced under 0.5 mM Sr(2+): (1) increase in type-B CO3 (2-) substitutions, which often lead to the creation of vacancies in Ca(2+) and OH(-) sites; (2) incorporation of Sr(2+) by substituting slightly less than 10 % of Ca(2+) in the apatite crystal lattice, resulting in an increase in both lattice parameters a and c; (3) change in the PO4 (3-) environments, possibly because of the expansion of the lattice; (4) the Ca/P ratio of this mineral was reduced, but its (Ca+Sr)/P ratio was the same as that of the control, indicating that its overall cation/P ratio was preserved. Thus, strontium ranelate changes the composition and crystal structure of the biological bone-like apatite produced in osteoblast cell cultures.

Stiffness calibration of qPlus sensors at low temperature through thermal noise measurements.

Non-contact atomic force microscopy (nc-AFM) offers a unique experimental framework for topographical imaging of surfaces with atomic and/or sub-molecular resolution. The technique also permits to perform frequency shift spectroscopy to quantitatively evaluate the tip-sample interaction forces and potentials above individual atoms or molecules. The stiffness of the probe, k, is then required to perform the frequency shift-to-force conversion. However, this quantity is generally known with little precision. An accurate stiffness calibration is therefore mandatory if accurate force measurements are targeted. In nc-AFM, the probe may either be a silicon cantilever, a quartz tuning fork (QTF), or a length extensional resonator (LER). When used in ultrahigh vacuum (UHV) and at low temperature, the technique mostly employs QTFs, based on the so-called qPlus design, which actually covers different types of sensors in terms of size and design of the electrodes. They all have in common a QTF featuring a metallic tip glued at the free end of one of its prongs. In this study, we report the stiffness calibration of a particular type of qPlus sensor in UHV and at 9.8 K by means of thermal noise measurements. The stiffness calibration of such high-k sensors, featuring high quality factors (Q) as well, requires to master both the acquisition parameters and the data post-processing. Our approach relies both on numerical simulations and experimental results. A thorough analysis of the thermal noise power spectral density of the qPlus fluctuations leads to an estimated stiffness of the first flexural eigenmode of ≃2000 N/m, with a maximum uncertainty of 10%, whereas the static stiffness of the sensor without tip is expected to be ≃3300 N/m. The former value must not be considered as being representative of a generic value for any qPlus, as our study stresses the influence of the tip on the estimated stiffness and points towards the need for the individual calibration of these probes. Although the framework focuses on a particular kind of sensor, it may be adapted to any high-k, high-Q nc-AFM probe used under similar conditions, such as silicon cantilevers and LERs.

Hyper-accumulation of vanadium in animals: Two sponges compete with urochordates.

Vanadium (V) concentrations in organisms are usually very low. To date, among animals, only some urochordate and annelid species contain very high levels of V in their tissues. A new case of hyper-accumulation of V in a distinct animal phylum (Porifera), namely, the two homoscleromorph sponge species Oscarella lobularis and O. tuberculata is reported. The measured concentrations (up to 30 g/kg dry weight) exceed those reported previously and are not found in all sponge classes. In both Oscarella species, V is mainly accumulated in the surface tissues, and in mesohylar cells, as V(IV), before being partly reduced to V(III) in the deeper tissues. Candidate genes from Bacteria and sponges have been identified as possibly being involved in the metabolism of V. This finding provides clues for the development of bioremediation strategies in marine ecosystems and/or bioinspired processes to recycle this critical metal.

Implications of receptor for advanced glycation end products for progression from obesity to diabetes and from diabetes to cancer.

Obesity and type 2 diabetes mellitus (T2DM) are chronic pathologies with a high incidence worldwide. They share some pathological mechanisms, including hyperinsulinemia, the production and release of hormones, and hyperglycemia. The above, over time, affects other systems of the human body by causing tissue hypoxia, low-grade inflammation, and oxidative stress, which lay the pathophysiological groundwork for cancer. The leading causes of death globally are T2DM and cancer. Other main alterations of this pathological triad include the accumulation of advanced glycation end products and the release of endogenous alarmins due to cell death (i.e., damage-associated molecular patterns) such as the intracellular proteins high-mobility group box protein 1 and protein S100 that bind to the receptor for advanced glycation products (RAGE) - a multiligand receptor involved in inflammatory and metabolic and neoplastic processes. This review analyzes the latest advanced reports on the role of RAGE in the development of obesity, T2DM, and cancer, with an aim to understand the intracellular signaling mechanisms linked with cancer initiation. This review also explores inflammation, oxidative stress, hypoxia, cellular senescence, RAGE ligands, tumor microenvironment changes, and the "cancer hallmarks" of the leading tumors associated with T2DM. The assimilation of this information could aid in the development of diagnostic and therapeutic approaches to lower the morbidity and mortality associated with these diseases.

Strontium is incorporated in different levels into bones and teeth of rats treated with strontium ranelate.

The aim of this study was to evaluate the strontium incorporation into specific bones and teeth of rats treated with strontium ranelate. The relative strontium levels [Sr/(Ca + Sr) ratio] were obtained by synchrotron radiation micro X-ray fluorescence. The incisor teeth were further examined by energy dispersive X-ray spectroscopy (EDS) in a scanning electron microscope. The isolated mineral phase was investigated by EDS in a transmission electron microscope and X-ray diffraction. The strontium content was markedly increased in animals treated with strontium ranelate, with different incorporation levels found among specific bones, regions within the same bone and teeth. The highest strontium levels were observed in the iliac crest, mandible and calvaria, while the lowest were observed in the femoral diaphysis, lumbar vertebrae, rib and alveolar bone. The strontium content was higher in the femoral neck than in the diaphysis. The strontium levels also varied within the alveolar bone. High levels of strontium were found in the incisor tooth, with values similar to those in the iliac crest. Strontium was observed in both enamel and dentin. The strontium content of the molar tooth was negligible. Strontium was incorporated into the mineral substance, with up to one strontium replacing one out of 10 calcium ions within the apatite crystal lattice. The mineral from treated animals presented increased lattice parameters, which might be associated to their bone strontium contents. In conclusion, the incorporation of strontium occurred in different levels into distinct bones, regions within the same bone and teeth of rats treated with strontium ranelate.

[Analysis of the inclusion of police personnel on the out of hospital cardiac arrest emergency response]. / Análisis de la inclusión de la policía en la respuesta de emergencias al paro cardiorrespiratorio extrahospitalario.

OBJECTIVE: Out-of-hospital cardiac arrest (OCHA) is a public health problem in which survival depends on community initial response among others. This study tries to analyze what's the proportional cost of enhancing such response by involving the police corps in it. MATERIALS AND METHODS: We analyzed retrospectively an OCHA registry started on June 2009. We contrasted a model with limited number of ambulances and police based first response. RESULTS: Mortality was 100%, response times high and 10.8% of the victims were receiving cardiopulmonary resuscitation (CPR) by bystanders. In 63.7% of the events the police arrived before the ambulance, in 1.5% of these cases the police provided CPR. The cost for each saved life was of 5.8-60 million Mexican pesos per life with only ambulance model vs 0.5-5.5 million Mexican pesos on a police first response model with 12 ambulances. CONCLUSIONS: In Queretaro interventions can be performed taking advantage of the response capacity of the existing police focused on diminishing mortality from OCHA at a lesser cost than delegating this function only to ambulances.

Gold-Coated Superparamagnetic Iron Oxide Nanoparticles Functionalized to EGF and Ce6 Complexes for Breast Cancer Diagnoses and Therapy.

Superparamagnetic iron oxide nanoparticles (SPIONs) have some limitations in the physiological environment, however, a modification on their surface, such as a core-shell structure with gold (SPIONs@Au), can enhance their applicability. In this study, SPIONs were synthesized by the chemical coprecipitation method, stabilized by sodium citrate, and followed by the gold-coating process. SPIONs@Au were functionalized with EGF-α-lipoic acid and chlorin e6 (Ce6)-cysteamine complexes, composing a Theranostic Nanoprobe (TP). The outcomes showed that the SPIONs@Au had changed in color to red and had an absorption band centered at 530 nm. The coating was verified in the TEM micrographs in bright and dark fields by EDS mapping, which indicated the presence of Au and Fe. The Ce6-cysteamine complex had a resonant band at 670 nm that enabled the diagnosis of biological samples using fluorescence analysis. In the measure of TNBC cell uptake, the maximum value of TP fluorescence intensity was obtained within 4 h of internalization. At 2 h, the incorporation of the TP in the cytoplasm as well as in the nuclei was observed, suggesting that it could be employed as a diagnostic marker. The PTT results showed significant percentages of apoptosis in the TNBC cell line, which confirms the efficacy of the TP.

4th generation synchrotron source boosts crystalline imaging at the nanoscale.

New 4th-generation synchrotron sources, with their increased brilliance, promise to greatly improve the performances of coherent X-ray microscopy. This perspective is of major interest for crystal microscopy, which aims at revealing the 3D crystalline structure of matter at the nanoscale, an approach strongly limited by the available coherent flux. Our results, based on Bragg ptychography experiments performed at the first 4th-generation synchrotron source, demonstrate the possibility of retrieving a high-quality image of the crystalline sample, with unprecedented quality. Importantly, the larger available coherent flux produces datasets with enough information to overcome experimental limitations, such as strongly deteriorated scanning conditions. We show this achievement would not be possible with 3rd-generation sources, a limit that has inhibited the development of this otherwise powerful microscopy method, so far. Hence, the advent of next-generation synchrotron sources not only makes Bragg ptychography suitable for high throughput studies but also strongly relaxes the associated experimental constraints, making it compatible with a wider range of experimental set-ups at the new synchrotrons.

Photoelectrochemical Enhancement of Graphene@WS2 Nanosheets for Water Splitting Reaction.

Tungsten disulfide nanosheets were successfully prepared by one-step chemical vapor deposition using tungsten oxide and thiourea in an inert gas environment. The size of the obtained nanosheets was subsequently reduced down to below 20 nm in width and 150 nm in length using high-energy ball milling, followed by 0.5 and 1 wt% graphene loading. The corresponding vibrational and structural characterizations are consistent with the fabrication of a pure WS2 structure for neat sampling and the presence of the graphene characteristic vibration modes in graphene@WS2 compounds. Additional morphological and crystal structures were examined and confirmed by high-resolution electron microscopy. Subsequently, the investigations of the optical properties evidenced the high optical absorption (98%) and lower band gap (1.75 eV) for the graphene@WS2 compared to the other samples, with good band-edge alignment to water-splitting reaction. In addition, the photoelectrochemical measurements revealed that the graphene@WS2 (1 wt%) exhibits an excellent photocurrent density (95 µA/cm2 at 1.23 V bias) compared with RHE and higher applied bias potential efficiency under standard simulated solar illumination AM1.5G. Precisely, graphene@WS2 (1 wt%) exhibits 3.3 times higher performance compared to pristine WS2 and higher charge transfer ability, as measured by electrical impedance spectroscopy, suggesting its potential use as an efficient photoanode for hydrogen evolution reaction.

Kinematic Analysis of the Underwater Undulatory Swimming Cycle: A Systematic and Synthetic Review.

The increase of low-cost technology for underwater filming has made quantitative analysis an affordable resource for swimming coaches on a frequent basis. In this context, a synthesis of the kinematic determinants of underwater undulatory swimming (UUS) seems to be lacking. The aim of the present study was to synthesise the scientific evidence on the kinematic characteristics of competitive swimmers during UUS and the main kinematic determinants of UUS performance, as well as to summarise the main methodological considerations for UUS kinematic analysis. A systematic literature search was performed through four electronic databases following the PRISMA guidelines and STROBE for evaluating the quality of the included studies. Twenty-three research studies from the first search and two from the second search were finally considered. In total, 412 competitive swimmers (321 males and 91 females) with a performance standard of international B (11%), national (51%), or regional (35%) level were analysed. Most studies focused on a two-dimensional analysis of the ventral UUS performed from a push start and filmed 6-12 m from the starting wall. Kinematic analysis of UUS included kicking parameters (kicking length, frequency, and amplitude) as well as selected segmental kinematics in 76% of studies and the analysis of UUS performance determinants in 36%. Information about the determinants of UUS performance was inconsistent due in part to inconsistencies in the definition of kinematic parameters. Further research studies where automatic motion capture systems are applied to the analysis of UUS on the aforementioned conditions should be conducted.

Use of failure-to-rescue after emergency surgery as a dynamic indicator of hospital resilience during the COVID-19 pandemic. A multicenter retrospective propensity score-matched cohort study.

BACKGROUND: Surgical failure-to-rescue (FTR, death rate following complications) is a reliable cross-sectional quality of care marker, but has not been evaluated dynamically. We aimed to study changes in FTR following emergency surgery during the COVID-19 pandemic. MATERIAL AND METHODS: Matched cohort study including all COVID-19-non-infected adult patients undergoing emergency general surgery in 25 Spanish hospitals during COVID-19 pandemic peak (March-April 2020), non-peak (May-June 2020), and 2019 control periods. A propensity score-matched comparative analysis was conducted using a logistic regression model, in which period was regressed on observed baseline characteristics. Subsequently, a mixed effects logistic regression model was constructed for each variable of interest. Main variable was FTR. Secondary variables were post-operative complications, readmissions, reinterventions, and length of stay. RESULTS: 5003 patients were included (948, 1108, and 2947 in the pandemic peak, non-peak, and control periods), with comparable clinical characteristics, prognostic scores, complications, reintervention, rehospitalization rates, and length of stay across periods. FTR was greater during the pandemic peak than during non-peak and pre-pandemic periods (22.5% vs. 17.2% and 12.7%), being this difference confirmed in adjusted analysis (odds ratio [OR] 2.13, 95% confidence interval [95% CI] 1.27-3.66). There was sensible inter-hospital variability in FTR changes during the pandemic peak (median FTR change +8.77%, IQR 0-29.17%) not observed during the pandemic non-peak period (median FTR change 0%, IQR -6.01-6.72%). Greater FTR increase was associated with higher COVID-19 incidence (OR 2.31, 95% CI 1.31-4.16) and some hospital characteristics, including tertiary level (OR 3.07, 95% CI 1.27-8.00), medium-volume (OR 2.79, 95% CI 1.14-7.34), and high basal-adjusted complication risk (OR 2.21, 95% CI 1.07-4.72). CONCLUSION: FTR following emergency surgery experienced a heterogeneous increase during different periods of the COVID-19 pandemic, suggesting it to behave as an indicator of hospital resilience. FTR monitoring could facilitate identification of centres in special needs during ongoing health care challenges.

Magnetosome chain superstructure in uncultured magnetotactic bacteria.

Magnetotactic bacteria produce magnetosomes, which are magnetic particles enveloped by biological membranes, in a highly controlled mineralization process. Magnetosomes are used to navigate in magnetic fields by a phenomenon called magnetotaxis. Two levels of organization and control are recognized in magnetosomes. First, magnetotactic bacteria create a spatially distinct environment within vesicles defined by their membranes. In the vesicles, the bacteria control the size, composition and purity of the mineral content of the magnetic particles. Unique crystal morphologies are produced in magnetosomes as a consequence of this bacterial control. Second, magnetotactic bacteria organize the magnetosomes in chains within the cell body. It has been shown in a particular case that the chains are positioned within the cell body in specific locations defined by filamentous cytoskeleton elements. Here, we describe an additional level of organization of the magnetosome chains in uncultured magnetotactic cocci found in marine and freshwater sediments. Electron microscopy analysis of the magnetosome chains using a goniometer showed that the magnetic crystals in both types of bacteria are not oriented at random along the crystal chain. Instead, the magnetosomes have specific orientations relative to the other magnetosomes in the chain. Each crystal is rotated either 60°, 180° or 300° relative to their neighbors along the chain axis, causing the overlapping of the (1 1 1) and [Formula in text] capping faces of neighboring crystals. We suggest that genetic determinants that are not present or active in bacteria with magnetosomes randomly rotated within a chain must be present in bacteria that organize magnetosomes so precisely. This particular organization may also be used as an indicative biosignature of magnetosomes in the study of magnetofossils in the cases where this symmetry is observed.