Submicron Aerosol Composition and Source Contribution across the Kathmandu Valley, Nepal, in Winter.

The Kathmandu valley experiences an average wintertime PM1 concentration of ∼100 µg m-3 and daily peaks over 200 µg m-3. We present ambient nonrefractory PM1 chemical composition, and concentration measured by a mini aerosol mass spectrometer (mAMS) sequentially at Dhulikhel (on the valley exterior), then urban Ratnapark, and finally suburban Lalitpur in winter 2018. At all sites, organic aerosol (OA) was the largest contributor to combined PM1 (C-PM1) (49%) and black carbon (BC) was the second largest contributor (21%). The average background C-PM1 at Dhulikhel was 48 µg m-3; the urban enhancement was 120% (58 µg m-3). BC had an average of 6.1 µg m-3 at Dhulikhel, an urban enhancement of 17.4 µg m-3. Sulfate (SO4) was 3.6 µg m-3 at Dhulikhel, then 7.5 µg m-3 at Ratnapark, and 12.0 µg m-3 at Lalitpur in the brick kiln region. Chloride (Chl) increased by 330 and 250% from Dhulikhel to Ratnapark and Lalitpur on average. Positive matrix factorization (PMF) identified seven OA sources, four primary OA sources, hydrocarbon-like (HOA), biomass burning (BBOA), trash burning (TBOA), a sulfate-containing local OA source (sLOA), and three secondary oxygenated organic aerosols (OOA). OOA was the largest fraction of OA, over 50% outside the valley and 36% within. HOA (traffic) was the most prominent primary source, contributing 21% of all OA and 44% of BC. Brick kilns were the second largest contributor to C-PM1, 12% of OA, 33% of BC, and a primary emitter of aerosol sulfate. These results, though successive, indicate the importance of multisite measurements to understand ambient particulate matter concentration heterogeneity across urban regions.

Aerosol Mass Spectral Profiles from NAMaSTE Field-Sampled South Asian Combustion Sources.

Unit mass resolution mass spectral profiles of nonrefractory submicron aerosol were retrieved from undersampled atmospheric emission sources common to South Asia using a "mini" aerosol mass spectrometer. Emission sources including wood- and dung-fueled cookstoves, agricultural residue burning, garbage burning, engine exhaust, and coal-fired brick kilns were sampled during the 2015 Nepal Ambient Monitoring and Source Testing Experiment (NAMaSTE) campaign. High-resolution peak fitting estimates of the mass spectra were used to characterize ions found within each source profile and help identify mass spectral signatures unique to aerosol emissions from the investigated source types. The first aerosol mass spectral profiles of dung burning, charcoal burning, garbage burning, and brick kilns are provided in this work. The online aerosol mass spectra show that organics were generally the dominant component of the nonrefractory aerosol. However, inorganic aerosol components including ammonium and chloride were significant in dung- and charcoal-fired cookstove emissions and sulfate compounds were major components of the coal-fired brick kiln emissions. Organic mass spectra from both the charcoal burning and zigzag brick kiln were dominated by nitrogen-containing ions thought to be from the electron ionization of amines and amides contained in the emissions. The mixed garbage burning emissions profiles were dominated by plastic combustion with very low fractions of organic markers associated with biomass burning. The plastic burning emissions were associated with enhanced organic signal at mass-to-charge (m/z) 104 and m/z 166, which could be useful fragment ion indicators for garbage burning in ambient aerosol profiles. Finally, a framework for the identification of emission sources using the unit mass resolution organic mass fractions at m/z 55 (f 55), m/z 57 (f 57), and m/z 60 (f 60) is proposed in this work. Plotting the ratio of f 55 to f 57 versus f 60 is found to be effective for the identification of emissions by the fuel type and even useful in separating emissions of similar source types. Although the sample size was limited, these results give further context to the aerosol and gas-phase emission factors presented in other NAMaSTE works and provide a critical reference for future aerosol composition measurements in South Asia.

Reactive Chlorine Species Reversibly Inhibit DnaB Protein Splicing in Mycobacteria.

Intervening proteins, or inteins, are mobile genetic elements that are translated within host polypeptides and removed at the protein level by splicing. In protein splicing, a self-mediated reaction removes the intein, leaving a peptide bond in place. While protein splicing can proceed in the absence of external cofactors, several examples of conditional protein splicing (CPS) have emerged. In CPS, the rate and accuracy of splicing are highly dependent on environmental conditions. Because the activity of the intein-containing host protein is compromised prior to splicing and inteins are highly abundant in the microbial world, CPS represents an emerging form of posttranslational regulation that is potentially widespread in microbes. Reactive chlorine species (RCS) are highly potent oxidants encountered by bacteria in a variety of natural environments, including within cells of the mammalian innate immune system. Here, we demonstrate that two naturally occurring RCS, namely, hypochlorous acid (the active compound in bleach) and N-chlorotaurine, can reversibly block splicing of DnaB inteins from Mycobacterium leprae and Mycobacterium smegmatis in vitro. Further, using a reporter that monitors DnaB intein activity within M. smegmatis, we show that DnaB protein splicing is inhibited by RCS in the native host. DnaB, an essential replicative helicase, is the most common intein-housing protein in bacteria. These results add to the growing list of environmental conditions that are relevant to the survival of the intein-containing host and influence protein splicing, as well as suggesting a novel mycobacterial response to RCS. We propose a model in which DnaB splicing, and therefore replication, is paused when these mycobacteria encounter RCS. IMPORTANCE Inteins are both widespread and abundant in microbes, including within several bacterial and fungal pathogens. Inteins are domains translated within host proteins and removed at the protein level by splicing. Traditionally considered molecular parasites, some inteins have emerged in recent years as adaptive posttranslational regulatory elements. Several studies have demonstrated CPS, in which the rate and accuracy of protein splicing, and thus host protein functions, are responsive to environmental conditions relevant to the intein-containing organism. In this work, we demonstrate that two naturally occurring RCS, including the active compound in household bleach, reversibly inhibit protein splicing of Mycobacterium leprae and Mycobacterium smegmatis DnaB inteins. In addition to describing a new physiologically relevant condition that can temporarily inhibit protein splicing, this study suggests a novel stress response in Mycobacterium, a bacterial genus of tremendous importance to humans.

Chemical and Physical Characterization of 3D Printer Aerosol Emissions with and without a Filter Attachment.

Fused filament fabrication three-dimensional (3D) printers have been shown to emit ultrafine particles (UFPs) and volatile organic compounds (VOCs). Previous studies have quantified bulk 3D printer particle and VOC emission rates, as well as described particle chemical composition via ex situ analysis. Here, we present size-resolved aerosol composition measurements from in situ aerosol mass spectrometry and ex situ transmission electron microscopy (TEM). Particles were sampled for in situ analysis during acrylonitrile butadiene styrene (ABS) and polylactic acid (PLA) 3D printing activities and ex situ analysis during ABS printing. We examined the effect of a high-efficiency particulate air filter attachment on ABS emissions and particle chemical composition and demonstrate that filtration was effective in preventing UFP emissions and that particles sampled during filtered prints did not have a high contribution (∼4% vs ∼10%) from aromatic ions in the mass spectrum. Ex situ analysis of particles collected during ABS printing was performed via TEM and electron energy loss spectroscopy, which indicated a high level of sp2 bonding type consistent with polymeric styrene. One 3D print with PLA resulted in an aerosol mass size distribution with a peak at ∼300 nm. Unfiltered ABS prints resulted in particle mass size distributions with peak diameters of ∼100 nm.

A comparison of clinical outcomes of acute testicular torsion between prepubertal and postpubertal males.

SHORT INTRODUCTION/BACKGROUND: Surgical intervention for acute testicular torsion can require either orchiopexy or orchiectomy. The decision of which surgery to perform is dependant on the amount of time that the testicle experienced ischemia and the viability of the testicle after reperfusion. OBJECTIVE: It is hypothesized that (1) there is a difference in orchiectomy and orchiopexy rates between prepubertal and postpubertal males with acute testicular torsion and (2) presenting symptoms may vary between the two age groups as prepubertal males may present with atypical symptoms, which could result in delayed presentation and diagnosis. STUDY DESIGN: A retrospective chart review was conducted on pediatric patients who were diagnosed with acute testicular torsion between June 2010 and August 2017. Demographic and clinical characteristics were extracted: age, ethnicity, referral pattern, primary insurance status, symptoms at presentation, prior history of ipsilateral testicular pain or intermittent torsion, recent trauma to genitalia, duration of symptoms (hours), gradual vs. acute onset of symptoms, time/weekday/season at presentation, and time interval from arrival at the study institution to surgical intervention (minutes). Patients were categorized into two groups: prepubertal group (age 1-12 years) and postpubertal group (age 13-18 years). Statistical analyses were performed using R, version 3.3.1. RESULTS: Ninety-one patients were included in the study. The overall orchiectomy rate was 30.8%. More prepubertal males underwent orchiectomy than postpubertal males (42.4% vs. 24.1%, respectively). Prepubertal males were more likely to present with abdominal pain than postpubertal males (27.3% vs. 10.3%, respectively). Those who underwent orchiectomy were more likely to present with longer duration of symptoms, testicular swelling, and abdominal pain than those who underwent orchiopexy. The risk of orchiectomy decreased by 14% per 1-year increase in age (odds ratio [OR]: 0.86, 95% confidence interval [CI]: 0.94-1.00, p = .009). A steady decline in the proportion of patients undergoing orchiectomy was seen from 1 to 12 years of age. DISCUSSION: This study found that prepubertal males are at higher risk for orchiectomy than postpubertal males. The risk of orchiectomy decreases by 14-16% per 1-year increase in age. Prepubertal males are more likely to present with atypical symptoms and delayed presentation and diagnosis, leading to delayed surgical intervention. It is important for providers to perform a genital examination in prepubertal males who present with abdominal pain to rule out acute testicular torsion. Patients presenting with longer duration of symptoms, testicular swelling, and abdominal pain are at higher risk for orchiectomy. No correlation was found between orchiectomy rate and ethnicity, referral status, primary insurance status, and time/weekday/season at presentation. CONCLUSION: Among patients presenting to a tertiary pediatric hospital with acute testicular torsion, prepubertal males (younger than 12 years) are at higher risk for orchiectomy than postpubertal males. Prepubertal males are more likely to present with atypical symptoms which results in delayed presentation and diagnosis, leading to delayed in surgical intervention.

Better wearing comfort of knee-length elastic compression stockings with an interface pressure of 18-21 mmHg compared to 23-32 mmHg in elderly people after a one day trial - Influence on foot deformities, rheumatism and arthritis.

BACKGROUND: Although the efficacy of compression therapy through knee-length compression stockings with an interface pressure of 18-21 mmHg for leg oedemas has been confirmed by many studies, 91% of patients are still treated with a higher interface pressure. METHOD: In this prospective open randomised monocentric study 19 patients (age ≥65, movement restrictions and symptomatic leg oedema) received knee-length compression stockings with an interface pressure of 18-21 mmHg (stocking type 1) and 23-32 mmHg (stocking type 2). On two consecutive days each of the two compression stocking types were worn for at least 8 hours. After this test period, both stocking types were assessed subjectively and skin changes were recorded. RESULT: A significantly (p-value <0.001) subjective improvement of the symptoms and complaints based on leg oedema was reported with the knee-length compression stockings. The Stocking type 1 recorded a significantly (p = 0,045) better wearing comfort. In addition, the Stocking type 2 was significantly too large amongst women in the front foot area (p = 0.044). The most common side effects were constrictions on the proximal lower leg (stocking type 1 = 73,7% (14/19); stocking type 2 = 78,9% (15/19)). Subjects with arthritis (p = 0.006), hallux valgus (p = 0.034) and/or digitus flexus (p = 0.021) found the socking type 1 significantly more comfortable. CONCLUSION: In order to achieve optimal patient compliance it is recommended to prescribe knee-length compression stockings with an interface pressure of 18-21 mmHg if the following criteria are met: age ≥65 years, female sex, arthritis, digitus flexus (claw toe) or hallux valgus.

Mechanics hands in patients with antisynthetase syndrome: 25 cases.

BACKGROUND: Antisynthetase antibodies (ASA) are directed against aminoacyl-tRNA-synthetases, ubiquitous enzymes of which eight types have hitherto been described. They are seen primarily in antisynthetase syndrome (ASS), in which diffuse interstitial lung disease is associated with inflammatory myopathy, joint involvement and cutaneous signs, in particular mechanic's hands. The aim of this study was to determine the prevalence and semiological characteristics of cutaneous involvement in patients presenting ASA. PATIENTS AND METHODS: We carried out a retrospective study of the medical files of patients with ASA diagnosed at the Strasbourg University Hospital between 1994 and 2009. RESULTS: We identified 22 women and 3 men presenting ASS (n=21), dermatomyositis (n=3) or sclerodermatomyositis (n=1). Mean age at the time of diagnosis was 56 years (12-79). The most commonly seen antibodies were anti-Jo1 (n=19), with the other cases of ASA involving anti-PL12 (n=3), anti-PL7 (n=2) and anti-EJ (n=1) antibodies. Five patients died from pulmonary complications. Mechanic's hands (characteristic plaques and papules along the edge of the first fingers on both hands) were found in 10 patients with ASS (7 cases) or dermatomyositis (3 cases), at the time of diagnosis in 7 cases and during a systemic episode in 3 cases. Muscular involvement was seen in all patients: 9 had diffuse interstitial lung disease and 8 had joint involvement. Cutaneous signs regressed totally or partially in all patients under treatment; in 6 patients, worsening was seen during systemic episodes of the disease. One of the 10 patients died through pulmonary complications. DISCUSSION: Mechanic's hands are a key indicator in cases of ASA and its outcome is intimately linked with underlying systemic involvement, particularly pulmonary. The characteristic semiology enables this disorder to be recognised and allows differentiation from psoriasis or irritant contact dermatitis of the hands, and it does not vary according to antibody. Whether or not the disease is life-threatening is unaffected by the presence of this sign.

Using integrated data analysis to extend measurement capability (invited).

The analysis approach called integrated data analysis (IDA) provides a means to exploit all information present in multiple streams of raw data to produce the best inference of a plasma parameter. This contrasts with the typical approach in which information (data) from a single diagnostic is used to measure a given parameter, e.g., visible bremsstrahlung → Z eff. Data from a given diagnostic usually contain information on many parameters. For example, a Thomson scattering diagnostic is sensitive to bremsstrahlung and line emission in addition to electron temperature. This background light is typically subtracted off and discarded but could be used to improve knowledge of Z eff. IDA encourages explicit awareness of such information and provides the quantitative framework to exploit it. This gives IDA the ability to increase spatial and temporal resolution, increase precision and accuracy of inferences, and measure plasma parameters that are difficult or impossible to measure using single diagnostic techniques. One example is the measurement of Z eff on Madison symmetric torus using IDA since no single diagnostic can provide a robust measurement. As we enter the burning plasma era, application of IDA will be critical to the measurement of certain parameters, as diagnostic access in the harsh fusion environment will be extremely limited.

Simulation, design, and first test of a multi-energy soft x-ray (SXR) pinhole camera in the Madison Symmetric Torus (MST).

A multi-energy soft x-ray pinhole camera has been designed and built for the Madison Symmetric Torus reversed field pinch to aid the study of particle and thermal-transport, as well as MHD stability physics. This novel imaging diagnostic technique combines the best features from both pulse-height-analysis and multi-foil methods employing a PILATUS3 x-ray detector in which the lower energy threshold for photon detection can be adjusted independently on each pixel. Further improvements implemented on the new cooled systems allow a maximum count rate of 10 MHz per pixel and sensitivity to the strong Al and Ar emission between 1.5 and 4 keV. The local x-ray emissivity will be measured in multiple energy ranges simultaneously, from which it is possible to infer 1D and 2D simultaneous profile measurements of core electron temperature and impurity density profiles with no a priori assumptions of plasma profiles, magnetic field reconstruction constraints, high-density limitations, or need of shot-to-shot reproducibility. The expected time and space resolutions will be 2 ms and <1 cm, respectively.

Parity-Engineered Light-Matter Interaction.

The concept of parity describes the inversion symmetry of a system and is of fundamental relevance in the standard model, quantum information processing, and field theory. In quantum electrodynamics, parity is conserved and large field gradients are required to engineer the parity of the light-matter interaction operator. In this work, we engineer a potassiumlike artificial atom represented by a specifically designed superconducting flux qubit. We control the wave function parity of the artificial atom with an effective orbital momentum provided by a resonator. By irradiating the artificial atom with spatially shaped microwave fields, we select the interaction parity in situ. In this way, we observe dipole and quadrupole selection rules for single state transitions and induce transparency via longitudinal coupling. Our work advances the design of tunable artificial multilevel atoms to a new level, which is particularly promising with respect to quantum chemistry simulations with near-term superconducting circuits.

Finite-time quantum entanglement in propagating squeezed microwaves.

Two-mode squeezing is a fascinating example of quantum entanglement manifested in cross-correlations of non-commuting observables between two subsystems. At the same time, these subsystems themselves may contain no quantum signatures in their self-correlations. These properties make two-mode squeezed (TMS) states an ideal resource for applications in quantum communication. Here, we generate propagating microwave TMS states by a beam splitter distributing single mode squeezing emitted from distinct Josephson parametric amplifiers along two output paths. We experimentally study the fundamental dephasing process of quantum cross-correlations in continuous-variable propagating TMS microwave states and accurately describe it with a theory model. In this way, we gain the insight into finite-time entanglement limits and predict high fidelities for benchmark quantum communication protocols such as remote state preparation and quantum teleportation.

Autofluorescence-Free Live-Cell Imaging Using Terbium Nanoparticles.

Fluorescent nanoparticles (NPs) have become irreplaceable tools for advanced cellular and subcellular imaging. While very bright NPs require excitation with UV or visible light, which can create strong autofluorescence of biological components, NIR-excitable NPs without autofluorescence issues exhibit much lower brightness. Here, we show the application of a new type of surface-photosensitized terbium NPs (Tb-NPs) for autofluorescence-free intracellular imaging in live HeLa cells. The combination of exceptionally high brightness, high photostability, and long photoluminecence (PL) lifetimes for highly efficient suppression of the short-lived autofluorescence allowed for time-gated PL imaging of intracellular vesicles over 72 h without toxicity and at extremely low Tb-NP concentrations down to 12 pM. Detection of highly resolved long-lifetime (ms) PL decay curves from small (∼10 µm2) areas within single cells within a few seconds emphasized the unprecedented photophysical properties of Tb-NPs for live-cell imaging that extend well beyond currently available nanometric imaging agents.

Observation of Electron Bernstein Wave Heating in a Reversed Field Pinch.

The first observation of rf heating in a reversed field pinch (RFP) using the electron Bernstein wave (EBW) is demonstrated on the Madison Symmetric Torus. Propagation across and heating in a stochastic magnetic field is observed. Novel techniques are required to measure the suprathermal electron tail generated by EBW heating in the presence of intense Ohmic heating. rf-heated electrons directly probe the edge transport properties in the RFP; measured loss rates imply a large noncollisional radial diffusivity.

Postural Stability after Unicondylar Knee Arthroplasty and Patient-Specific Interpositional Knee Spacer.

Purpose and Hypothesis. Knee osteoarthritis results, inter alia, in decreased postural stability. After arthroplasty, postural stability recovers, but it is unclear whether this can be ascribed to a reduction of pain or to the preserving of receptor-rich intraarticular soft tissue and natural knee kinematics. The objective of this study was to evaluate whether an unicondylar knee arthroplasty provides better results regarding postural stability or a patient-specific knee spacer. Methods. In this comparative study, we assessed functional results and postural stability 16 months after 20 unicondylar knee arthroplasties (group A) and 20 patient-specific interpositional knee device implantations (group B). Patients were evaluated using the KSS and WOMAC score. Postural stability was analysed during single leg stance on a force platform (Biodex Balance System). Results. Concerning postural stability, range of motion (ROM), and KSS 16 months after the procedure, there were no significant differences between both groups. Conclusion. Successful treatment of knee osteoarthritis restores postural stability to the level of the contralateral side, regardless of the implant device.

Photon Statistics of Propagating Thermal Microwaves.

In experiments with superconducting quantum circuits, characterizing the photon statistics of propagating microwave fields is a fundamental task. We quantify the n^{2}+n photon number variance of thermal microwave photons emitted from a blackbody radiator for mean photon numbers, 0.05≲n≲1.5. We probe the fields using either correlation measurements or a transmon qubit coupled to a microwave resonator. Our experiments provide a precise quantitative characterization of weak microwave states and information on the noise emitted by a Josephson parametric amplifier.

Food Insecurity and Peripheral Arterial Disease in Older Adult Populations.

OBJECTIVES: Food insecurity, defined as the limited or uncertain availability of nutritious and safe foods, is a complex phenomenon and is linked to poor nutrition and diet-sensitive chronic diseases. Dietary patterns that include saturated fats and meat products are potential risk factors for the progression of peripheral arterial disease (PAD). This study explored whether there is a relationship between food insecurity and PAD among a national sample of older adults. DESIGN: We conducted a cross-sectional data analysis using data from the 1999-2004 National Health and Nutrition Examination Survey (NHANES). Food security was assessed using the US Household Food Security Survey Module. Bivariate analyses were conducted using the Rao-Scott Chi-square test to examine associations between PAD and sociodemographic variables. Multivariable generalized logistic regression was employed to assess the effect of food security on the presence of PAD, with adjustment for respondent's socio demographic characteristics. PARTICIPANTS: A total of 2,027 adults with PAD were included (Ankle Brachial Index (ABI) score ≤ 0.90).We excluded participants less than 60 years of age. RESULTS: Compared to older adults who are food secure, those who are food insecure have an increased risk for PAD. Food insecurity is associated with peripheral arterial disease among older adults (adults adjusted odds ratio, 1.50 [95% CI 1.11-2.03). CONCLUSION: Older adults with peripheral arterial disease are experiencing food insecurity. While nutrition and PAD are not well-defined, previous literature indicates there is a connection between food insecurity and diet-sensitive chronic diseases (diabetes and hypertension) which are risk factors for PAD. Food insecurity should be taken into consideration when treating older adults with PAD to help decrease poor health outcomes that are linked to an insufficient amount of nutritious foods.

Calibration of a two-color soft x-ray diagnostic for electron temperature measurement.

The two-color soft x-ray (SXR) tomography diagnostic on the Madison Symmetric Torus is capable of making electron temperature measurements via the double-filter technique; however, there has been a 15% systematic discrepancy between the SXR double-filter (SXRDF) temperature and Thomson scattering (TS) temperature. Here we discuss calibration of the Be filters used in the SXRDF measurement using empirical measurements of the transmission function versus energy at the BESSY II electron storage ring, electron microprobe analysis of filter contaminants, and measurement of the effective density. The calibration does not account for the TS and SXRDF discrepancy, and evidence from experiments indicates that this discrepancy is due to physics missing from the SXRDF analysis rather than instrumentation effects.

Weight management for adolescents with intellectual and developmental disabilities: Rationale and design for an 18month randomized trial.

Adolescents with intellectual and developmental disabilities (IDD) are an underserved group in need of weight management. However, information regarding effective weight management for this group is limited, and is based primarily on results from small, non-powered, non-randomized trials that were not conducted in accordance with current weight management guidelines. Additionally, the comparative effectiveness of emerging dietary approaches, such as portion-controlled meals (PCMs) or program delivery strategies such as video chat using tablet computers have not been evaluated. Therefore, we will conduct an 18month trial to compare weight loss (6months) and maintenance (7-18months) in 123 overweight/obese adolescents with mild to moderate IDD, and a parent, randomized to a weight management intervention delivered remotely using FaceTime™ on an iPad using either a conventional meal plan diet (RD/CD) or a Stop Light diet enhanced with PCMs (RD/eSLD), or conventional diet delivered during face-to-face home visits (FTF/CD). This design will provide an adequately powered comparison of both diet (CD vs. eSLD) and delivery strategy (FTF vs. RD). Exploratory analyses will examine the influence of behavioral session attendance, compliance with recommendations for diet (energy intake), physical activity (min/day), self-monitoring of diet and physical activity, medications, and parental variables including diet quality, physical activity, baseline weight, weight change, and beliefs and attitudes regarding diet and physical activity on both weight loss and maintenance. We will also complete a cost and contingent valuation analysis to compare costs between RD and FTF delivery.

Displacement of Propagating Squeezed Microwave States.

Displacement of propagating quantum states of light is a fundamental operation for quantum communication. It enables fundamental studies on macroscopic quantum coherence and plays an important role in quantum teleportation protocols with continuous variables. In our experiments, we have successfully implemented this operation for propagating squeezed microwave states. We demonstrate that, even for strong displacement amplitudes, there is no degradation of the squeezing level in the reconstructed quantum states. Furthermore, we confirm that path entanglement generated by using displaced squeezed states remains constant over a wide range of the displacement power.

A virtual reality intervention (Second Life) to improve weight maintenance: Rationale and design for an 18-month randomized trial.

Despite the plethora of weight loss programs available in the US, the prevalence of overweight and obesity (BMI≥25kg/m(2)) among US adults continues to rise at least, in part, due to the high probability of weight regain following weight loss. Thus, the development and evaluation of novel interventions designed to improve weight maintenance are clearly needed. Virtual reality environments offer a promising platform for delivering weight maintenance interventions as they provide rapid feedback, learner experimentation, real-time personalized task selection and exploration. Utilizing virtual reality during weight maintenance allows individuals to engage in repeated experiential learning, practice skills, and participate in real-life scenarios without real-life repercussions, which may diminish weight regain. We will conduct an 18-month effectiveness trial (6 months weight loss, 12 months weight maintenance) in 202 overweight/obese adults (BMI 25-44.9kg/m(2)). Participants who achieve ≥5% weight loss following a 6month weight loss intervention delivered by phone conference call will be randomized to weight maintenance interventions delivered by conference call or conducted in a virtual environment (Second Life®). The primary aim of the study is to compare weight change during maintenance between the phone conference call and virtual groups. Secondarily, potential mediators of weight change including energy and macronutrient intake, physical activity, consumption of fruits and vegetables, self-efficacy for both physical activity and diet, and attendance and completion of experiential learning assignments will also be assessed.