Impact of the Hunga Tonga volcanic eruption on stratospheric composition.

The explosive eruption of the Hunga Tonga-Hunga Ha'apai (HTHH) volcano on 15 January 2022 injected more water vapor into the stratosphere and to higher altitudes than ever observed in the satellite era. Here, the evolution of the stratospherically injected water vapor is examined as a function of latitude, altitude, and time in the year following the eruption (February to December 2022), and perturbations to stratospheric chemical composition resulting from the increased sulfate aerosols and water vapor are identified and analyzed. The average calculated mass distribution of elevated water vapor between hemispheres is approximately 78% Southern Hemisphere (SH) and 22% Northern Hemisphere in 2022. Significant changes in stratospheric composition following the HTHH eruption are identified using observations from the Aura Microwave Limb Sounder satellite instrument. The dominant features in the monthly mean vertical profiles averaged over 15° latitude ranges are decreases in O3 (-14%) and HCl (-22%) at SH midlatitudes and increases in ClO (>100%) and HNO3 (43%) in the tropics, with peak pressure-level perturbations listed. Anomalies in column ozone from 1.2-100 hPa due to the HTHH eruption include widespread O3 reductions in SH midlatitudes and O3 increases in the tropics, with peak anomalies in 15° latitude-binned, monthly averages of approximately -7% and +5%, respectively, occurring in austral spring. Using a 3-dimensional chemistry-climate-aerosol model and observational tracer correlations, changes in stratospheric composition are found to be due to both dynamical and chemical factors.

Method for the production of a compact source of atomic line spectra in the vacuum ultraviolet.

Atomic emission spectra provide a means to identify and to gain insight into the electronic structure of emitting or absorbing matter. Detailed procedures are provided for the construction of low-pressure electrodeless discharge lamps that yield targeted emission in the vacuum ultraviolet for the spectroscopic study of water vapor and halogen species aboard an array of airborne observation platforms in the upper atmosphere, as well as in laboratory environments. While specific to the production of Lyman-alpha, atomic chlorine, and atomic bromine emissions in this study, the configuration of the lamps and their interchangeability with respect to operation lend these procedures to constructing sources engaging a wide selection of atomic and molecular spectra with straightforward modifications. The features and limitations of each type of lamp are discussed, as well as methods to improve spectral purity and factors affecting operational lifetime.

Newborn metabolic vulnerability profile identifies preterm infants at risk for mortality and morbidity.

BACKGROUND: Identifying preterm infants at risk for mortality or major morbidity traditionally relies on gestational age, birth weight, and other clinical characteristics that offer underwhelming utility. We sought to determine whether a newborn metabolic vulnerability profile at birth can be used to evaluate risk for neonatal mortality and major morbidity in preterm infants. METHODS: This was a population-based retrospective cohort study of preterm infants born between 2005 and 2011 in California. We created a newborn metabolic vulnerability profile wherein maternal/infant characteristics along with routine newborn screening metabolites were evaluated for their association with neonatal mortality or major morbidity. RESULTS: Nine thousand six hundred and thirty-nine (9.2%) preterm infants experienced mortality or at least one complication. Six characteristics and 19 metabolites were included in the final metabolic vulnerability model. The model demonstrated exceptional performance for the composite outcome of mortality or any major morbidity (AUC 0.923 (95% CI: 0.917-0.929). Performance was maintained across mortality and morbidity subgroups (AUCs 0.893-0.979). CONCLUSIONS: Metabolites measured as part of routine newborn screening can be used to create a metabolic vulnerability profile. These findings lay the foundation for targeted clinical monitoring and further investigation of biological pathways that may increase the risk of neonatal death or major complications in infants born preterm. IMPACT: We built a newborn metabolic vulnerability profile that could identify preterm infants at risk for major morbidity and mortality. Identifying high-risk infants by this method is novel to the field and outperforms models currently in use that rely primarily on infant characteristics. Utilizing the newborn metabolic vulnerability profile for precision clinical monitoring and targeted investigation of etiologic pathways could lead to reductions in the incidence and severity of major morbidities associated with preterm birth.

Stratospheric ozone over the United States in summer linked to observations of convection and temperature via chlorine and bromine catalysis.

We present observations defining (i) the frequency and depth of convective penetration of water into the stratosphere over the United States in summer using the Next-Generation Radar system; (ii) the altitude-dependent distribution of inorganic chlorine established in the same coordinate system as the radar observations; (iii) the high resolution temperature structure in the stratosphere over the United States in summer that resolves spatial and structural variability, including the impact of gravity waves; and (iv) the resulting amplification in the catalytic loss rates of ozone for the dominant halogen, hydrogen, and nitrogen catalytic cycles. The weather radar observations of ∼2,000 storms, on average, each summer that reach the altitude of rapidly increasing available inorganic chlorine, coupled with observed temperatures, portend a risk of initiating rapid heterogeneous catalytic conversion of inorganic chlorine to free radical form on ubiquitous sulfate-water aerosols; this, in turn, engages the element of risk associated with ozone loss in the stratosphere over the central United States in summer based upon the same reaction network that reduces stratospheric ozone over the Arctic. The summertime development of the upper-level anticyclonic flow over the United States, driven by the North American Monsoon, provides a means of retaining convectively injected water, thereby extending the time for catalytic ozone loss over the Great Plains. Trusted decadal forecasts of UV dosage over the United States in summer require understanding the response of this dynamical and photochemical system to increased forcing of the climate by increasing levels of CO2 and CH4.

Initial Metabolic Profiles Are Associated with 7-Day Survival among Infants Born at 22-25 Weeks of Gestation.

OBJECTIVE: To evaluate the association between early metabolic profiles combined with infant characteristics and survival past 7 days of age in infants born at 22-25 weeks of gestation. STUDY DESIGN: This nested case-control consisted of 465 singleton live births in California from 2005 to 2011 at 22-25 weeks of gestation. All infants had newborn metabolic screening data available. Data included linked birth certificate and mother and infant hospital discharge records. Mortality was derived from linked death certificates and death discharge information. Each death within 7 days was matched to 4 surviving controls by gestational age and birth weight z score category, leaving 93 cases and 372 controls. The association between explanatory variables and 7-day survival was modeled via stepwise logistic regression. Infant characteristics, 42 metabolites, and 12 metabolite ratios were considered for model inclusion. Model performance was assessed via area under the curve. RESULTS: The final model included 1 characteristic and 11 metabolites. The model demonstrated a strong association between metabolic patterns and infant survival (area under the curve [AUC] 0.885, 95% CI 0.851-0.920). Furthermore, a model with just the selected metabolites performed better (AUC 0.879, 95% CI 0.841-0.916) than a model with multiple clinical characteristics (AUC 0.685, 95% CI 0.627-0.742). CONCLUSIONS: Use of metabolomics significantly strengthens the association with 7-day survival in infants born extremely premature. Physicians may be able to use metabolic profiles at birth to refine mortality risks and inform postnatal counseling for infants born at <26 weeks of gestation.

Violent injuries and regional correlates among women in China: results from 21 cities study in China.

BACKGROUND: Ecological models depict violent injuries against women being influenced by both individual and environmental characteristics. However, only few studies examined the association between regional variables and the likelihood of violent injuries. Our study is a preliminary assessment of the impact of regional variables on the likelihood that a woman has experienced violent injuries. METHODS: Participants were 16 866 urban residents, who were identified through a multi-stage sampling process conducted in 21 Chinese cities. Out of the sampled population, 8071 respondents were female. Subsequent analyses focused solely on the female sample. Multilevel logistic regression analyses were performed to examine regional variation in violent injuries. RESULTS: Prevalence of violent injuries against women is 10.7% (95% CI: 7.8%, 15.5%). After controlling for individual-level characteristics, higher regional male-female ratio (OR: 1.97, P < 0.05), population growth rate (OR: 4.12, P < 0.01) and unemployment rate (OR: 2.45, P < 0.01) were all associated with an elevated risk of violent injuries among Chinese women caused by physical attack. CONCLUSIONS: The results suggest violent injuries among Chinese women caused by physical attack have become an important social and public health problem. The findings point to the importance of developing effective health policies, laws and interventions that focuses on the unequal economic development between different regions.

Experiences of pursuing an intensivist career in regional and rural Australia: An interview study.

The regional and rural intensivist workforce is vital to delivering high standards of healthcare to all Australians. Currently, there is an impending workforce disaster, with higher senior medical officer vacancy rates among regional and rural intensive care units, with these units being staffed by junior doctors who are in earlier stages of their training, which in turn increases supervisory burden. There is a lack of comprehensive literature on the barriers and enablers of training, recruiting and retaining regional and rural intensivists. To address this gap, a qualitative study was conducted, involving 13 in-depth, structured interviews with full-time and part-time intensivists from eight Australian regional and rural hospitals. Content analysis of the interview data resulted in the identification of four major categories: unique practice context, need for a broad generalist skill set, perks and challenges of working in a regional/rural area and workforce implications. The study findings revealed that regional and rural intensive care practice offers positive aspects, including work satisfaction, supportive local teams and an appealing lifestyle. However, these benefits are counterbalanced by challenges such as a heavier burden of on-call work, a higher proportion of junior staff which increase supervisory burden and limited access to subspecialist services. The implications of these findings are noteworthy and can be utilised to inform government policies, hospitals, the College of Intensive Care Medicine and the Australian and New Zealand College of Anaesthetists in developing strategies to enhance the provision of intensive care services and improve workforce planning in regional and rural areas.

Single-mode 2.65 µm InGaAsSb/AlInGaAsSb laterally coupled distributed-feedback diode lasers for atmospheric gas detection.

We demonstrate index-coupled distributed-feedback diode lasers at 2.65 µm that are capable of tuning across strong absorption lines of HDO and other isotopologues of H2O. The lasers employ InGaAsSb/AlInGaAsSb multi-quantum-well structures grown by molecular beam epitaxy on GaSb, and single-mode emission is generated using laterally coupled second-order Bragg gratings etched alongside narrow ridge waveguides. We verify near-critical coupling of the gratings by analyzing the modal characteristics of lasers of different length. With an emission facet anti-reflection coating, 2-mm-long lasers exhibit a typical current threshold of 150 mA at 20 °C and are capable of emitting more than 25 mW in a single longitudinal mode, which is significantly higher than the output power reported for loss-coupled distributed-feedback lasers operating at similar wavelengths.

Co-worker characteristics and nurses' safety-climate perceptions.

PURPOSE: Previous research indicates that nurses' safety-climate perceptions are influenced by individual nurse characteristics, leadership, staffing levels and workplace structure. No literature was identified that explored the relationship between nurses' safety climate perceptions and staffing composition in a particular hospital unit. This paper aims to fill some of the gaps in the research in this area. DESIGN/METHODOLOGY/APPROACH: Data supplied by 430 registered nurses working in two Midwestern US hospitals were analyzed to co-worker characteristics such as education, licensure, experience and full- or part-time status. FINDINGS: Registered nurses working in hospitals with proportionally more-experienced nurses perceived their workplaces to be significantly safer for patients. Surprisingly, co-worker licensure, education and full- or part-time status did not significantly influence nurses' safety climate perceptions. PRACTICAL IMPLICATIONS: Findings indicate that safety-climate perceptions vary significantly between hospital units and experienced nurses may act as a resource that promotes a positive safety climate. Hospitals retaining experienced nurses may potentially reduce errors. ORIGINALITY/VALUE: The paper illustrates that the results highlight the importance of providing nurses with an environment that encourages retention and creates a workplace where experienced nurses' skills are best utilized.

What nurses are talking about: content and community within a nursing online forum.

There is little research on the use of online forums by nursing professionals as a way of creating community and exchanging professional knowledge. The purpose of this study is to analyze the content of an online nursing forum to determine the potential of online forums to constitute a community of practice among nurses. We examined one month of thread topics from a nursing focused general discussion forum and categorized (294 discussion threads) according to content. The most frequent topics of discussion were advice regarding career planning and clinical/technical questions. The majority of posts dealt directly with the domain of nursing. The finding that nurses are seeking information about clinical tasks from unverified anonymous online sources raises concerns about the safety culture of health care institutions.

Nature of the chemical bond in transition: dissection of radical-molecule reactivity.

A complete method for quantifying the Born-Oppenheimer barriers of radical--molecule abstraction reactions is derived from first principles with the dual objectives of analytical prediction and conceptual understanding. Expanding upon the work of Donahue et al. (J. Phys. Chem. A 1998, 102, 3923-3933) this treatment uses the strategic construction of reactant-like and product-like wave functions to evaluate the coupling between crossing diabatic states. The overall reaction coordinate is evaluated in a modular fashion, whereby each region is analyzed within the context of its governing physics.

Delivery of psychosocial care for cancer patients: a pilot investigation.

Psychosocial distress is common in cancer patients. Although common, psychosocial distress is frequently under-diagnosed and poorly managed in the U.S. health system. This paper describes 25 in-depth telephone interviews with health care professionals working within cancer care centers. Interview questions address perception of the psychosocial services offered within their cancer care organizations. Results indicate that access to psychosocial care is frequently dependent upon the subjective judgment of busy clinicians. Information technology could improve the delivery of psychosocial care by easing the administration of psychosocial assessments and increasing clinician contact with research evidence regarding distress management.

Racial and ethnic disparities in outcomes through 1 year of life in infants born prematurely: a population based study in California.

OBJECTIVES: To investigate racial/ethnic differences in rehospitalization and mortality rates among premature infants over the first year of life. STUDY DESIGN: A retrospective cohort study of infants born in California from 2011 to 2017 (n = 3,448,707) abstracted from a California Office of Statewide Health Planning and Development database. Unadjusted Kaplan-Meier tables and logistic regression controlling for health and sociodemographic characteristics were used to predict outcomes by race/ethnicity. RESULTS: Compared to White infants, Hispanic and Black early preterm infants were more likely to be readmitted; Black late/moderate preterm (LMPT) infants were more likely to be readmitted and to die after discharge; Hispanic and Black early preterm infants with BPD were more likely to be readmitted; Black LMPT infants with RDS were more likely to be readmitted and die after discharge. CONCLUSIONS: Racial/ethnic disparities in readmission and mortality rates exist for premature infants across several co-morbidities. Future studies are needed to improve equitability of outcomes.

Experimental evidence for the pressure dependence of the reaction rate constant between acetic acid and hydroxyl radicals.

The reaction rate constant of acetic acid with the hydroxyl radical is measured at 93 Torr with our high-pressure flow system (HPFS) and found to display a negative temperature dependence that can be described by the Arrhenius expression, k(T) = (2.44 ± 0.22) × 10(-14) exp ((1027 ± 24)/T)) cm(3) molecule(-1) s(-1). Compared with our previously reported 7 Torr data, we find a noticeable pressure dependence. This dependence is observed to increase with decreasing temperature. This finding is consistent with a termolecular reaction mechanism. It is the first experimental evidence of the pressure dependence for this rate constant. A kinetics model is constructed, and the model results agree qualitatively with our experimental data. The extrapolated rate constant of the title reaction would be faster than previously believed at conditions of the upper troposphere/lower stratosphere, suggesting that the importance of acetic acid in its impact on HO(x) chemistry is currently underestimated.

The role of health literacy, depression, disease knowledge, and self-efficacy in self-care among adults with heart failure: An updated model.

BACKGROUND: Patients with inadequate health literacy and heart failure face high healthcare costs, more hospitalizations, and greater mortality. To address these negative consequences, patients need to improve heart failure self-care. Multiple factors may influence self-care, but the exact model by which they do so is not fully understood. OBJECTIVES: The objective of this study was to examine a model exploring the contribution of health literacy, depression, disease knowledge, and self-efficacy to the performance of heart failure self-care. METHODS: Using a cross-sectional design, patients were recruited from a heart failure clinic and completed validated assessments of their cognition, health literacy, depression, knowledge, self-efficacy and self-care. Patients were separated into two groups according to their health literacy level: inadequate/marginal and adequate. Differences between groups were assessed with an independent t-test. Hypothesized paths and mediated relationships were estimated and tested using observed variable path analysis. RESULTS: Participants (n = 100) were mainly male (67%), white (93%), and at least had a high school education (85%). Health literacy was associated with disease knowledge (path coefficient=0.346, p = 0.002), depression was negatively associated with self-efficacy (path coefficient=-0.211, p = 0.037), self-efficacy was positively associated with self-care (path coefficient=0.402, p<0.0005), and there was evidence that self-efficacy mediated the link between depression and self-care. There was no evidence of: mediation of the link between health literacy and self-care by knowledge or self-efficacy; positive associations between knowledge and self-efficacy or self-care; or mediation of the disease knowledge and self-care relationship by self-efficacy. Further, depression was associated with self-care indirectly rather than also directly as hypothesized. CONCLUSIONS: Self-efficacy and depression are associated with heart failure self-care. Data generated from the model suggest that healthcare professionals should actively engage all patients to gain self-efficacy and address depression to positively affect heart failure self-care.

Chlorine-catalyzed ozone destruction: Cl atom production from ClOOCl photolysis.

Recent laboratory measurements of the absorption cross sections of the ClO dimer, ClOOCl, have called into question the validity of the mechanism that describes the catalytic removal of ozone by chlorine. Here we describe direct measurements of the rate-determining step of that mechanism, the production of Cl atoms from the photolysis of ClOOCl, under laboratory conditions similar to those in the stratosphere. ClOOCl is formed in a cold-temperature flowing system, with production initiated by a microwave discharge of Cl(2) or photolysis of CF(2)Cl(2). Excimer lasers operating at 248, 308, and 352 nm photodissociate ClOOCl, and the Cl atoms produced are detected with time-resolved atomic resonance fluorescence. Cl(2), the primary contaminant, is measured directly for the first time in a ClOOCl cross section experiment. We find the product of the quantum yield of the Cl atom production channel of ClOOCl photolysis and the ClOOCl absorption cross section, (phisigma)(ClOOCl) = 660 +/- 100 at 248 nm, 39.3 +/- 4.9 at 308 nm, and 8.6 +/- 1.2 at 352 nm (units of 10(-20) cm(2) molecule(-1)). The data set includes 468 total cross section measurements over a wide range of experimental conditions, significantly reducing the possibility of a systematic error impacting the results. These new measurements demonstrate that long-wavelength photons (lambda = 352 nm) are absorbed by ClOOCl directly, producing Cl atoms with a probability commensurate with the observed rate of ozone destruction in the atmosphere.

Experimental study of the kinetics of the reaction of acetic acid with hydroxyl radicals from 255 to 355 K.

The rate constant of the reaction of OH with acetic acid over the temperature range of 255-355 K was determined using our High-Pressure Flow System with laser-induced fluorescence detection of the OH radicals and FTIR spectrometry for acetic acid quantification. The rate constant displays a negative temperature dependence and can be described by the Arrhenius expression: k(1)(T) = (5.38 +/- 0.28) x 10(-14) exp(740 +/- 51/T) cm(3) molecule (-1) s(-1), with k(1) = (6.77 +/- 0.14) x 10(-13) cm(3) molecule (-1) s(-1) at 295 K. The negative temperature dependence suggests a pre-reactive complex formation between the OH radicals and the acetic acid monomer, and this result is consistent with previous reports. The use of FTIR spectrometry allows for separation of the acetic acid monomer and dimer in the spectrum and gives a measurement of the acetic acid monomer that is independent of the temperature measurement and free of reliance on an equilibrium constant expression that can introduce high uncertainty. The highly sensitive laser-induced fluorescence for OH detection coupled with the FTIR spectrometry result in a rate constant measurement with low uncertainty, and the data set presented here in the temperature range of 255-355K serves to bridge existing data sets that are obtained either above or below room temperature.

Rate constants of nine C6-C9 alkanes with OH from 230 to 379 K: chemical tracers for [OH].

We report absolute rate-constant measurements for the reactions of nine C(6)-C(9) alkanes with OH in 8-10 torr of nitrogen from 230 to 379 K in the Harvard University High-Pressure Flow System. Hydroxyl concentrations were measured using laser-induced fluorescence, and alkane concentrations were measured using Fourier transform infrared Spectroscopy. Ethane's reactivity was simultaneously measured as a test of experimental performance. Results were fit to a modified Arrhenius equation based on transition state theory (ignoring tunneling), k(T) = Be(-E(a)/T)/(T(1 - e(- 1.44nu(1)/T))(2)(1 - e(- 1.44nu(2)/T)), with nu(1) and nu(2) bending frequencies, set to 280 and 500 cm(-1). Results were as follows for B (10(-9) K cm(3) s(-1)), E(a) (K), and k(298) (10(-12) cm(3) s(-1)): cyclohexane, 3.24 +/- 0.14, 332 +/- 12, 7.13; cyclo-octane, 3.47 +/- 0.30, 149 +/- 26, 14.1; 2-methylhexane, 1.45 +/- 0.08, 110 +/- 15, 6.72; 3-methylhexane, 1.50 +/- 0.08, 128 +/- 16, 6.54; methylcyclopentane, 1.65 +/- 0.07, 109 +/- 13, 7.65; methylcyclohexane, 1.86 +/- 0.09, 83 +/- 14, 9.43; methylcycloheptane, 3.45 +/- 0.45, 142 +/- 36, 14.4; n-propylcyclohexane, 2.83 +/- 0.14, 112 +/- 15, 13.0; isopropylcyclohexane, 1.79 +/- 0.11, -44 +/- 34, 13.9. Uncertainties are one sigma results from linear regression fits and are likely underestimated. Room temperature rate coefficients of reaction are accurate to within 10% at two sigma. A comprehensive fit to 17 separate studies including the present work for cyclohexane gives good agreement with the present results: terms as above, 3.09 +/- 0.12, 326 +/- 12, 6.96. Five of these compounds are routinely measured in urban air within a suite of atmospheric nonmethane hydrocarbons and reach parts per billion levels. The remaining four are C8-C9 cycloalkanes with low anthropogenic emissions. Because of their high, specific reactivity with OH, their concentration decays may be used as an indirect measurement of [OH] in the atmosphere or laboratory. This data set serves to further constrain the reaction barriers for cyclohexane and cyclo-octane, is the first temperature-dependent study for methylcyclopentane and methylcyclohexane, and provides the first measurements for the rate constants of the remaining five hydrocarbons. Reactivity follows general trends observed for other saturated alkanes, increasing with size and extent of substitution. Reaction barriers are heavily influenced by the presence of tertiary hydrogens. The reaction barrier for cyclo-octane is significantly lower than that for cyclohexane, a result that is not predicted from our current understanding of hydrocarbon reactivity.

Predicting EQ-5D utility scores from the 25-item National Eye Institute Vision Function Questionnaire (NEI-VFQ 25) in patients with age-related macular degeneration.

PURPOSE: In this study, we explored different statistical approaches to identify the best algorithm to predict EQ-5D utility scores from the NEI-VFQ 25 in patients with age-related macular degeneration (AMD). METHODS: Ordinary least squares (OLS), Tobit, and censored least absolute deviation (CLAD) approaches were compared using cross-sectional data (primary dataset, n = 151) at screening from a phase I/II clinical trial in patients with AMD. Three models were specified in this study: full (includes all 12 dimensions of the NEI-VFQ 25), short (includes only the general health dimension and the composite score), and reduced model (using stepwise regression). To evaluate the predictive accuracy of the models, the mean absolute prediction error (MAPE), mean error, and root means squared error were calculated using in-sample cross-validation (within the primary dataset) and out-of-sample validation using an independent dataset (n = 393). The model that provided the lowest prediction errors was chosen as the best model. RESULTS: In-sample cross-validation and out-of-sample validation consistently demonstrated that, compared to other approaches, heteroscedasticity-adjusted OLS produced the lowest MAPE (mean values were 0.1400, 0.1593, respectively) for the full model, while CLAD performed best for the short and reduced models (mean values were 0.1299, 0.1483, respectively). The normality and homoscedasticity assumptions of both OLS and Tobit were rejected. CLAD, however, can accommodate these particular violations. CONCLUSIONS: The CLAD-short model is recommended for producing the EQ-5D utility scores when only the NEI-VFQ 25 data are available.

Pump-enhanced difference-frequency generation at 3.3 microm.

The demonstration of continuous wave intracavity difference-frequency generation in the mid-infrared (mid-IR) is presented. A cavity for pump laser enhancement is constructed around a periodically poled lithium niobate crystal, and the cavity length is locked to the frequency of the pump laser using the Pound-Drever-Hall technique, producing a gain of 12 in the resultant idler power compared to the single-pass case. A widely tunable single-mode 3.3 microm idler beam with a power of nearly 10 mW is available for direct absorption spectroscopy. The pump-enhancement method demonstrated here should be readily scalable to produce hundreds of milliwatts of mid-IR light by using higher power signal and pump lasers.