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Atherosclerosis, or hardening of the arteries, is caused by the buildup of lipids (fats) and connective tissues inside the walls of the arteries. This complex mechanism of plaque formation is described. The resulting lesions are difficult to measure, complicating treatment evaluation. Angiography, X-ray imaging of the arteries, is of limited value in detecting plaques, and is not well suited to calculating the extent of atherosclerosis, although computerized image analysis now provides more objective measures. Clinical end points, such as fatal and nonfatal heart attack or unstable angina (pain from reduced blood flow to the heart), or other deaths related to the heart can also be used to measure the effectiveness of treatment. Regression and prevention of atherosclerosis in studies of animals and humans are discussed. In humans, atherosclerotic plaques contain collagen (connective tissue), calcium and lipids, and often relatively little lipid is present. If humans are similar to animal models, lipids are removed quickly, but collagen is removed slowly, suggesting that treatment to reduce these lesions must be very slow. However, new lesions may be prevented and lesions containing greater amounts of lipids may respond to treatment. Data are required on both the severity of disease and on the rate of complications from atherosclerosis to determine the effectiveness of treatment. Several trials of treatments for atherosclerosis are reviewed. (Consumer Summary produced by Reliance Medical Information, Inc.)

Rheumatoid arthritis (RA) is a chronic disease that primarily affects the joints, causing inflammation that leads to pain. Because surrounding bone tissue can degenerate as well, joint malformations occur. Until recently, it has not been appreciated that bone loss can occur early in the course of RA. It is well known that a lack of exercise can cause generalized bone loss, and since people with RA have painful joints, they tend to decrease their activity. Therefore there is controversy about whether the bone loss seen in RA is a specific feature of the disease itself, or the result of reduced activity. Normal bone, like most other body tissues, is lost and replaced on a continual basis, and there are various hormones and enzymes in the body that control bone turnover. These include parathyroid hormone (PTH), which may contribute to the disease process in RA that causes rapid, early bone loss. A study of bone loss was undertaken with a group of 17 white women with classic RA of the wrist and 18 age-matched white women who did not have RA. They were all postmenopausal and in generally good health. The density of their bones was measured in the large bone of the lower arm and in the spine of the lower back. X-rays of the hands were taken at the start of the study and again in two to three years. The subjects underwent certain laboratory studies, as well, to determine rates of bone turnover. There was a disproportionately rapid loss of bone near the affected joint in those with RA; the farther away from the affected joint, the less the bone loss. Bone loss in the two groups of women was similar at the farther sites. In RA, the bone loss was rapid at first and slower as the disease progressed. The authors suggest that one way to preserve bone near the affected joints may be to suppress the body's secretion of PTH and maybe even calcitriol, another hormone; the latter can be accomplished by taking substantial doses of calcium. It has been shown that calcium supplements do help in postmenopausal osteoporosis, but the authors note that taking calcium did not correlate with preserving bone in this study. (Consumer Summary produced by Reliance Medical Information, Inc.)

(Anesth Analg. 2022;135:191–197)Placenta accreta spectrum (PAS) disorder is a high-risk, life-threatening illness for pregnant women and its incidence has increased over time. Peripartum complications include massive blood loss, intensive care unit admission, and hysterectomy. Guidelines recommend a multidisciplinary team for PAS disorder management, within which anesthesiologists play an important role as they manage peridelivery care, oversee transfusion-related decisions, and oversee postpartum analgesia. Despite anesthesiologists’ key involvement in PAS disorder management during the peripartum period, the relationship between anesthesiologist involvement and maternal and neonatal outcomes in patients with PAS lacks data. This Special Article analyzes knowledge gaps in anesthesia care for patients with PAS disorder and what research is required to bridge these gaps.

(J Clin Anesth. 2021;75:110484. doi: 10.1016/j.jclinane.2021.110484)Rotational thromboelastometry (ROTEM) provides point-of-care technology for detecting hyperfibrinolysis, a condition that can precede coagulopathy and lead to excessive bleeding with childbirth. Early awareness of the contribution of hyperfibrinolysis to postpartum hemorrhage in patients allows for targeted anti-fibrinolytic treatment that can reduce the risk of severe bleeding. This study investigates the efficacy of ROTEM for predicting the development of excessive blood loss by timely detection of hyperfibrinolysis at the earliest stages of severe hemorrhage. In addition, anticoagulation therapy is increasing in the obstetric population in response to thromboembolism as a primary cause of maternal mortality.

Prior studies demonstrate that most living kidney donors (LKDs) report no adverse psychosocial outcomes; however, changes in psychosocial functioning at the individual donor level have not been routinely captured. We studied psychosocial outcomes predonation and at 1, 6, 12, and 24 months postdonation in 193 LKDs and 20 healthy controls (HCs). There was minimal to no mood disturbance, body image concerns, fear of kidney failure, or life dissatisfaction, indicating no incremental changes in these outcomes over time and no significant differences between LKDs and HCs. The incidence of any new‐onset adverse outcomes postdonation was as follows: mood disturbance (16%), fear of kidney failure (21%), body image concerns (13%), and life dissatisfaction (10%). Multivariable analyses demonstrated that LKDs with more mood disturbance symptoms, higher anxiety about future kidney health, low body image, and low life satisfaction prior to surgery were at highest risk of these same outcomes postdonation. It is important to note that some LKDs showed improvement in psychosocial functioning from pre‐ to postdonation. Findings support the balanced presentation of psychosocial risks to potential donors as well as the development of a donor registry to capture psychosocial outcomes beyond the mandatory 2‐year follow‐up period in the United States. In this multi‐site, prospective analysis of living kidney donors, a small minority of donors experience new‐onset adverse psychosocial outcomes in the first two years following donation, although these outcomes might not differ significantly from those of healthy nondonors over a similar time period.

(Anesth Analg. 2021;133:462–473. doi: 10.1213/ANE.0000000000005592)From the beginning of the Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) outbreak to January 17, 2021, there was an interest concerning and growing research on pregnancy and SARS-CoV-2, but little data had been gathered and analyzed comparing obstetric patients with and without the virus with regards to anesthetic management. The Society for Obstetric Anesthesia and Perinatology (SOAP) coronavirus disease 2019 (COVID-19) registry was made primarily to better understand anesthetic management and obstetric outcomes in women with and without SARS-CoV-2 during hospital delivery at widespread-testing institutions.

We report the determination from high-resolution spectra of the atmospheric parameters and abundances of 13 chemical species (among which lithium) in 8 single-lined active binaries. These data are combined with our previous results for 6 other RS CVn systems to examine a possible relationship between the photospheric abundance patterns and the stellar activity level. The stars analyzed are generally found to exhibit peculiar abundance ratios compared to inactive, Galactic disk stars of similar metallicities. We argue that this behaviour is unlikely to be an artefact of errors in the determination of the atmospheric parameters or non-standard mixing processes along the red giant branch, but diagnoses instead the combined action of various physical processes related to activity. The most promising candidates are cool spot groups covering a very substantial fraction of the stellar photosphere or NLTE effects arising from nonthermal excitation. However, we cannot exclude the possibility that more general shortcomings in our understanding of K-type stars (e.g. inadequacies in the atmospheric models) also play a significant role. Lastly, we call attention to the unreliability of the ($V-R$) and ($V-I$) colour indices as temperature indicators in chromospherically active stars.

One of the goals of the ground-based support program for the corotand mons/rømersatellite missions is to characterize suitable target stars for the part of the missions dedicated to asteroseismology. We present the detailed abundance analysis of nine of the potential corotmain targets using the semi-automatic software vwa. For two additional corottargets we could not perform the analysis due to the high rotational velocity of these stars. For five stars with low rotational velocity we have also performed abundance analysis by a classical equivalent width method in order to test the reliability of the vwasoftware. The agreement between the different methods is good. We find that it is necessary to measure abundances extracted from each line relative to the abundances found from a spectrum of the Sun in order to remove systematic errors. We have constrained the global atmospheric parameters Teff, $\log g$, and [Fe/H] to within $70{-}100$K, $0.1{-}0.2$dex, and 0.1 dex for five stars which are slow rotators ($v\sin i < 15 {\rm km\,s}^{-1}$). For most of the stars we find good agreement with the parameters found from line depth ratios, H αlines, Strömgren indices, previous spectroscopic studies, and also $\log g$determined from the hipparcosparallaxes. For the fast rotators ($v\sin i > 60 {\rm km\,s}^{-1}$) it is not possible to constrain the atmospheric parameters.

Photospheric parameters and abundances are presented for a sample of single-lined chromospherically active binaries from a differential LTE analysis of high-resolution spectra. Abundances have been derived for 13 chemical species, including several key elements such as Li, Mg, and Ca. Two methods have been used. The effective temperatures, surface gravities and microturbulent velocities were first derived from a fully self-consistent analysis of the spectra, whereby the temperature is determined from the excitation equilibrium of the $\ion{Fe}{i}$lines. The second approach relies on temperatures derived from the ($B-V$) colour index. These two methods give broadly consistent results for the stars in our sample, suggesting that the neutral iron lines are formed under conditions close to LTE. We discuss the reliability in the context of chromospherically active stars of various colour indices used as temperature indicators, and conclude that the ($V-R$) and ($V-I$) colours are likely to be significantly affected by activity processes. Irrespective of the method used, our results indicate that the X-ray active binaries studied are not as metal poor as previously claimed, but are at most mildly iron-depleted relative to the Sun ($-0.41\la {\rm [Fe/H]}\la+0.11$). A significant overabundance of several chemical species is observed (e.g., the α-synthezised elements). These abundance patterns are discussed in relation to stellar activity.

We have computed a grid of synthetic spectra in the wavelength range $\lambda\lambda$4600–5600 Å using revised model atmospheres, for a range of atmospheric parameters and values of [ $\alpha\mbox{-elements/Fe}] = 0.0$and +0.4. The Lick indices Fe5270, Fe5335, Mgb and Mg2are measured on the grid spectra for $FWHM = 2$to 8.3 Å. Relations between the indices Fe5270, Fe5335 and Mg2and the stellar parameters effective temperature $T_{\rm eff}, \log\; g$, [Fe/H] and [ α/Fe] , valid in the range $4000 \leq T_{\rm eff} \leq 7000$K, are presented. These fitting functions are given for $FWHM = 3.5$and 8.3 Å. The indices were also measured for a list of 97 reference stars with well-known stellar parameters observed at ESO and OHP, and these are compared to the computed indices. Finally, a comparison of the indices measured on the observed spectra and those derived from the fitting functions based on synthetic spectra is presented.

Some living kidney donors (LKDs) incur costs associated with donation, although these costs are not well characterized in the United States. We collected cost data in the 12 mo following donation from 182 LKDs participating in the multicenter prospective Kidney Donor Outcomes Cohort (KDOC) Study. Most LKDs (n = 167, 92%) had one direct cost or more following donation, including ground transportation (86%), health care (41%), meals (53%), medications (36%), lodging (23%), and air transportation (12%). LKDs missed 33 072 total work hours, 40% of which were unpaid and led to $302 175 in lost wages (mean $1660). Caregivers lost $68 655 in wages (mean $377). Although some donors received financial assistance, 89% had a net financial loss in the 12‐mo period, with one‐third (33%) reporting a loss exceeding $2500. Financial burden was higher for those with greater travel distance to the transplant center (Spearman's ρ = 0.26, p < 0.001), lower household income (Spearman's ρ = −0.25, p < 0.001), and more unpaid work hours missed (Spearman's ρ = 0.52, p < 0.001). Achieving financial neutrality for LKDs must be an immediate priority for the transplant community, governmental agencies, insurance companies, nonprofit organizations, and society at large. Data from the multi‐center, prospective Kidney Donor Outcomes Cohort (KDOC) study shows that most donors experience direct costs, substantial lost wages, and a net financial loss in the first year after living kidney donation. See the editorial on page 741 from Formica and Newell.

The high-resolution optical spectra of the two X-ray active binaries RS CVn stars HD 113816 (IS Vir) and HD 119285 (V851 Cen) are analysed and their Na, Mg, Al, Si, Ca, Sc, Ti, Co and Ni contents determined, in the framework of a larger program of chemical analysis of RS CVn stellar atmosphere. The analysis of IS Vir and V851 Cen is performed with three different LTE methods. In the first one, abundances are derived for a large set of transitions (among which 28 Fe ilines, spanning a broad interval in excitation potential and equivalent width, and 6 Fe iitransitions) using measured equivalent widths and Kurucz LTE model atmospheres as input for the MOOG software package. The input atmospheric parameters and abundances are iteratively modified until (i) the Fe iabundances exhibit no trend with excitation potential or equivalent width, (ii) Fe iand Fe iiaverage abundances are the same and (iii) Fe and Alpha elements average abundances are consistent with the input values. The second method follows a similar approach, but uses a restricted line list (without the Fe i“low excitation potential” transitions) and relies on the $B-V$and $V-I$colour indices to determine the temperature. The third method uses the same restricted line list as the second method and relies on fitting the 6162 Å Ca iline wing profiles to derive the surface gravity. The reliability of these methods is investigated in the context of single line RS CVn stars. It is shown that the $V-I$photometric index gives, on a broader sample of stars, significantly cooler estimates of the effective temperature than the $B-V$index. All approaches give results in good agreement with each other, except the $V-I$based method. The analysis of IS Vir and V851 Cen results in both cases in their primaries being giant stars of near-solar metallicity. Their parameters as derived with the first method are respectively $T_{\rm eff} = 4720$K, $\log g = 2.65$, ${\rm [Fe/H]} = +0.04$and $T_{\rm eff} = 4700$K, $\log g = 3.0$and ${\rm [Fe/H]} = -0.13$. In the case of V851 Cen the derived iron content is significantly higher than a previous determination in the literature. Both stars exhibit relative overabundances of several elements (e.g. Ca) with respect to the solar mix.

We present several new sets of grids of model stellar atmospheres computed with modified versions of the ATLAS9 code. Each individual set consists of several grids of models with different metallicities ranging from [M/H] $= -$2.0 to +1.0 dex. The grids range from 4000 to 10 000 K in Teffand from 2.0 to 5.0 dex in $\log{g}$. The individual sets differ from each other and from previous ones essentially in the physics used for the treatment of the convective energy transport, in the higher vertical resolution of the atmospheres and in a finer grid in the (Teff, $\log{g}$) plane. These improvements enable the computation of derivatives of color indices accurate enough for pulsation mode identification. In addition, we show that the chosen vertical resolution is necessary and sufficient for the purpose of stellar interior modelling. To explain the physical differences between the model grids we provide a description of the currently available modifications of ATLAS9 according to their treatment of convection. Our critical analysis of the dependence of the atmospheric structure and observable quantities on convection treatment, vertical resolution and metallicity reveals that spectroscopic and photometric observations are best represented when using an inefficient convection treatment. This conclusion holds whatever convection formulation investigated here is used, i.e. MLT($\alpha=0.5$), CM and CGM are equivalent. We also find that changing the convection treatment can lead to a change in the effective temperature estimated from Strömgren color indices from 200 to 400 K.

The evolution of the Milky Way disk, which contains most of the stars in the Galaxy, is affected by several phenomena. For example, the bar and the spiral arms of the Milky Way induce radial migration of stars1and can trap or scatter stars close to orbital resonances2. External perturbations from satellite galaxies can also have a role, causing dynamical heating of the Galaxy3, ring-like structures in the disk4and correlations between different components of the stellar velocity5. These perturbations can also cause ‘phase wrapping’ signatures in the disk6–9, such as arched velocity structures in the motions of stars in the Galactic plane. Some manifestations of these dynamical processes have already been detected, including kinematic substructure in samples of nearby stars10–12, density asymmetries and velocities across the Galactic disk that differ from the axisymmetric and equilibrium expectations13, especially in the vertical direction11,14–16, and signatures of incomplete phase mixing in the disk7,12,17,18. Here we report an analysis of the motions of six million stars in the Milky Way disk. We show that the phase-space distribution contains different substructures with various morphologies, such as snail shells and ridges, when spatial and velocity coordinates are combined. We infer that the disk must have been perturbed between 300 million and 900 million years ago, consistent with estimates of the previous pericentric passage of the Sagittarius dwarf galaxy. Our findings show that the Galactic disk is dynamically young and that modelling it as time-independent and axisymmetric is incorrect.

Limited information exists on the predonation costs incurred by eventual living kidney donors (LKDs). Expenses related to completion of the donation evaluation were collected from 194 LKDs participating in the multi-center, prospective Kidney Donor Outcomes Cohort (KDOC) Study. Most LKDs (n = 187, 96%) reported one or more direct costs, including ground transportation (80%), healthcare (24%), lodging (17%) and air transportation (14%), totaling $101 484 (USD; mean = $523 ± 942). Excluding paid vacation or sick leave, donor and companion lost wages totaled $35 918 (mean = $187 ± 556) and $14 378 (mean = $76 ± 311), respectively. One-third of LKDs used paid vacation or sick leave to avoid incurring lost wages. Few LKDs reported receiving financial support from the transplant candidate (6%), transplant candidate’s family (3%), a nonprofit organization (3%), the National Living Donor Assistance Center (7%), or transplant center (3%). Higher total costs were significantly associated with longer distance traveled to the transplant center (p < 0.001); however, total costs were not associated with age, sex, race/ethnicity, household income, marital status, insurance status, or transplant center. Moderate predonation direct and indirect costs are common for adults who complete the donation evaluation. Potential LKDs should be advised of these possible costs, and the transplant community should examine additional strategies to reimburse donors for them.

Gels are one of the soft material platforms being evaluated to deliver topically acting anti-HIV drugs (microbicides) to the vaginal environment. For each drug, its loaded concentration, gel properties and applied volume, and frequency of dosing can be designed to optimize PK and, thence, PD. These factors also impact user sensory perceptions and acceptability. Deterministic compartmental modeling of vaginal deployment and drug delivery achieved by test gels can help delineate how multiple parameters characterizing drug, vehicle, vaginal environment, and dosing govern details of PK and PD and also gel leakage from the canal. Such microbicide delivery is a transport process combining convection, e.g., from gel spreading along the vaginal canal, with drug diffusion in multiple compartments, including gel, mucosal epithelium, and stroma. The present work builds upon prior models of gel coating flows and drug diffusion (without convection) in the vaginal environment. It combines and extends these initial approaches in several key ways, including: (1) linking convective drug transport due to gel spreading with drug diffusion and (2) accounting for natural variations in dimensions of the canal and the site of gel placement therein. Results are obtained for a leading microbicide drug, tenofovir, delivered by three prototype microbicide gels, with a range of rheological properties. The model includes phosphorylation of tenofovir to tenofovir diphosphate (which manifests reverse transcriptase activity in host cells), the stromal concentration distributions of which are related to reference prophylactic values against HIV. This yields a computed summary measure related to gel protection (“percent protected”). Analyses illustrate tradeoffs amongst gel properties, drug loading, volume and site of placement, and vaginal dimensions, in the time and space history of gel distribution and tenofovir transport to sites of its anti-HIV action and concentrations and potential prophylactic actions of tenofovir diphosphate therein.

A library of 211 echelle spectra taken with ELODIE at the Observatoire de Haute-Provence is presented. It provides a set of spectroscopic standards covering the full range of gravities and metallicities in the effective temperature interval [4000 K, 6300 K]. The spectra are straightened, wavelength calibrated, cleaned of cosmic ray hits, bad pixels and telluric lines. They cover the spectral range [440 nm, 680 nm] with an instrumental resolution of 42000. For each star, basic data were compiled from the Hipparcos catalogue and the Hipparcos Input Catalogue. Radial velocities with a precision better than 100 $\mathrm{m~s}^{-1}$are given. Atmospheric parameters ($T_\mathrm{eff}$, $\log g$, [Fe/H]) from the literature are discussed. Because of scattered determinations in the bibliography, even for the most well-known stars, these parameters were adjusted by an iterative process which takes account of common or different spectral features between the standards, using our homogeneous set of spectra. Revised values of effective temperature, gravity and metallicity are proposed. They are still consistent with the literature, and also lead to the self-consistency of the library, in the sense that similar spectra have similar atmospheric parameters. This adjustment was performed by using step by step a method based on the least square comparison of carefully prepared spectra, which was originally developed for the on-line estimation of the atmospheric parameters of faint field stars (companion paper in the main journal).

Le but de ce travail est d’étudier l’impact sur le recouvrement clinique du respect ou non du seuil douloureux dans la prise en charge des épaules enraidies.

Les auteurs ont individualisé et évalué l’impact des exercices de rééducation conventionnelle et des exercices d’autorééducation sur l’évolution clinique des patients rééduqués pour épaule raide et proposent un protocole de prise en charge de rééducation.

La raideur de l’épaule est un symptôme fréquent associé à des tableaux cliniques multiples et dont la prise en charge est insuffisamment définie.

United Network for Organ Transplantation (UNOS) policy 3.6.4.5.1 provides exception points to patients diagnosed with hepatopulmonary syndrome (HPS) to compensate for their reported increased mortality risk. We compared pre- and posttransplant and overall outcomes in 255 patients receiving exception points under this policy (HPS policy patients) with 32 358 nonexception control patients listed in the model for end-stage liver disease (MELD) era to determine whether the intent of the policy is being met.

(Anesth Analg. 2020;130:436–444)As births using assisted reproductive technology increase, the maternal and neonatal safety of these pregnancies continues to be of concern. There are established associations between assisted reproductive technology pregnancies and a number of adverse outcomes, including gestational diabetes, hypertensive disorders of pregnancy, obstetric hemorrhage, abnormal placentation, and cesarean delivery. There is a lack of studies examining the risk of intensive care unit (ICU) admission in women using assisted reproductive technology. This study compared parturients who conceived via in vitro fertilization (IVF) and those who did not in terms of etiology and course of ICU admission, particularly focusing on postpartum hemorrhage.

(Anesth Analg. 2019. doi: 10.1213/ANE.0000000000004155)At term, about 3% to 4% of worldwide pregnancies have a fetus in the breech presentation, a common risk factor for delivery complications. The current recommendation to reduce perinatal morbidity and mortality with breech presentation is to perform a cesarean delivery. An alternative is external cephalic version, in which the fetus is manually rotated into vertex position to allow for an attempted vaginal delivery. The success rate of this procedure increases via utilization of neuraxial anesthesia, which allows for the relaxation of abdominal muscles, and via tocolytic agents which provide uterine relaxation. Two examples of such tocolytic agents are nitroglycerin and terbutaline. The authors of this study hypothesized that no difference in the successful cephalic version rate would exist between nitroglycerin and terbutaline.

Large outbreaks of giardiasis caused by person-to-person transmission, or a combination of transmission routes, have not previously been reported. A large, prolonged giardiasis outbreak affected families belonging to a country club in a suburb of Boston, Massachusetts, during June–December 2003. We conducted a retrospective cohort study to determine the source of this outbreak. Giardiasis-compatible illness was experienced by 149 (25%) respondents to a questionnaire, and was laboratory confirmed in 97 (65%) of these cases. Of the 30 primary cases, exposure to the children's pool at the country club was significantly associated with illness (risk ratio 3·3, 95% confidence interval 1·7–6·5). In addition, 105 secondary cases probably resulted from person-to-person spread; 14 cases did not report an onset date. This outbreak illustrates the potential for Giardia to spread through multiple modes of transmission, with a common-source outbreak caused by exposure to a contaminated water source resulting in subsequent prolonged propagation through person-to-person transmission in the community. This capacity for a common-source outbreak to continue propagation through secondary person-to-person spread has been reported with Shigella and Cryptosporidium and may also be a feature of other enteric pathogens having low infectious doses.

To compare the efficacy and safety of rivastigmine (3 to 6 mg/day) vs placebo over 12 weeks in patients with traumatic brain injury and persistent cognitive impairment.

We treated eight dysplastic acetabula in six skeletally mature patients with Down’s syndrome by a modified Bernese periacetabular osteotomy. The mean age at the time of surgery was 16.5 years (12.8 to 28.5). Mean length of follow-up was five years (2 to 10.4).Pre-operatively the mean (Tönnis) acetabular angle was 28°, the centre-edge angle was -9°, and the extrusion index was 60%; post-operatively they were 3°, 37°, and 17%, respectively. Two patients with post-operative (Tönnis) acetabular angles > 10° developed subluxation post-operatively and required secondary varus derotation femoral osteotomies. Another patient developed a late labral tear which was treated arthroscopically. All eight hips remain clinically stable, and are either asymptomatic or symptomatically improved.These results suggest that the modified Bernese periacetabular osteotomy can be used successfully in the treatment of acetabular dysplasia in patients with Down’s syndrome.

Tension-free vaginal tape (TVT) has been introduced and demonstrated to be an effective treatment for stress urinary incontinence. Improved general health in the elderly population has led to a greater number of patients seeking surgical treatment for incontinence. We evaluated the impact of TVT on quality of life in elderly patients, defined as age 70 and older.

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Kinetic studies of the reactions of 3-pentoxy with NO and O2 have been performed using laser-induced fluorescence detection of 3-pentoxy radicals. Experiments were carried out at a total pressure of 50 Torr at subambient temperatures. Arrhenius expressions are obtained for the reactions of 3-pentoxy with NO (kNO) and O2 (kO2):  kNO = (5.6 ± 1.6) × 10^-13 exp[(7.8 ± 0.6) kJ mol^-1/RT] cm³ molecule^-1 s^-1 (216−276 K), and kO2 = (4.1 ± 1.2) × 10^-15 exp[(2.6 ± 0.6) kJ mol^-1/RT] cm³ molecule^-1 s^-1 (220−285 K). No pressure dependence was observed for either rate constant at 243 K between 50 and 150 Torr. The negative temperature dependence of kNO is significantly larger than that of other alkoxy radicals, and this suggests a 298 K rate constant that is only one-third to half those measured for other alkoxy radicals. The small negative temperature dependence of kO2 is different from the small positive temperature dependence observed for ethoxy and propoxy radicals but is comparable to that previously observed for 2-butoxy radicals. The observed temperature dependencies of kNO and kO2 confound expectations that the kinetics of the reactions of larger alkoxy radicals would be very similar to the kinetics of C1−C3 alkoxy radicals.

We combine scanning tunneling spectroscopy and photoluminescence excitation spectroscopy (PLE) to study the electronic level structure and single electron charging effects of InAs and novel InAs/ZnSe core/shell nanocrystal quantum dots. The two techniques provide complementary information on the electronic structure of these systems. In the tunneling spectra of core InAs nanocrystals grown by colloidal chemistry, 2–7 nm in diameter, we directly identify atomic-like electronic quantum dot states with s and p character as two- and sixfold charging multiplets. These measurements are correlated with the low temperature PLE data and, surprisingly, excellent agreement was observed between spacings of levels detected by the two techniques, yielding new information on the quantum dot level structure. The combined tunneling and optical spectroscopy approach was also applied to the study of InAs/ZnSe core/shell nanocrystals, which have a high fluorescence quantum yield in the near IR range. The tunneling spectroscopy shows changes in their electronic structure compared to the cores with the s–p gap closing in thicker shells. This observation is supported by PLE spectroscopy, establishing the effectiveness of the combined optical-tunneling spectroscopy approach in the study of quantum dots.

The early role of natural killer cells and gamma delta T cells in the development of protective immunity to the blood stage of nonlethal Plasmodium yoelii infection was studied. Splenic cytokine levels were measured 24 h after infection of natural killer cell-depleted immunodeficient and littermate mice or transiently T-cell-depleted normal mice. Splenic gamma interferon levels were significantly increased above background in immunodeficient and littermate mice 24 h after infection. Depletion of natural killer cells resulted in markedly depressed gamma interferon levels and poor control of parasitemia, particularly in severe combined immunodeficient mice. In the littermates, gamma interferon levels were partially reduced, but parasitemias were resolved normally. However, in athymic mice, natural killer cell depletion had no effect on gamma interferon production. Levels of tumor necrosis factor alpha were increased in all animals 24 h after infection, and responses were not affected by natural killer cell depletion. However, in T-cell-depleted animals, both gamma interferon and tumor necrosis factor alpha levels were decreased 24 h after infection, and depleted mice were unable to control their parasitemia. These results suggest that the early production of both cytokines is important in the early control of parasitemia and that both natural killer and gamma delta T cells contribute equally towards their production. The data also suggest that the subsequent resolution of infection requires early production of gamma interferon, which might act by switching on the appropriate T-helper-cell subsets and other essential parasitotoxic effector mechanisms.

Fluorescence excitation spectra of tert-pentoxy [CH3CH2C(O·)(CH3)2] and 3-pentoxy radicals were observed for the first time. The radicals were produced by laser photolysis of the corresponding pentyl nitrites at 355 nm and studied in the wavelength range 345−400 nm. For tert-pentoxy, 12 vibronic bands were labeled in three progressions. One dominant progression corresponds to the C−O stretch mode with initial vibrational interval 551 ± 10 cm^-1. Two other unknown mode progressions have vibrational intervals of 587 ± 10 and 631 ± 10 cm^-1. The transition origin was tentatively assigned at 25 491 ± 10 cm^-1 (392.3 ± 0.1 nm). For 3-pentoxy, 15 vibronic bands were labeled in three progressions. The vibrational intervals in each progression are of consistent anharmonic tendency. On the basis of our assignments of the C−O stretch progression, the transition origin T0, the C−O stretching vibration frequency νC-O, and the anharmonic constant χC-O are derived to be 26 437 ± 10, 578 ± 6, and −17 ± 2 cm^-1, respectively. The initial vibrational intervals of two other unknown modes are 596 ± 10 and 590 ± 10 cm^-1. The fluorescence lifetime of 3-pentoxy was determined to be about 150 ns. The short extent of the laser-induced fluorescence (LIF) excitation spectra of many C2−C5 alkoxy radicals is tentatively explained as arising from the opening of a predissociation channel at relatively low excitation energies. Results of efforts to obtain LIF excitation spectra for 10 additional large alkoxy radicals are reported.