Ground penetrating radar observations of the contact between the western delta and the crater floor of Jezero crater, Mars.

The delta deposits in Jezero crater contain sedimentary records of potentially habitable conditions on Mars. NASA's Perseverance rover is exploring the Jezero western delta with a suite of instruments that include the RIMFAX ground penetrating radar, which provides continuous subsurface images that probe up to 20 meters below the rover. As Perseverance traversed across the contact between the Jezero crater floor and the delta, RIMFAX detected a distinct discontinuity in the subsurface layer structure. Below the contact boundary are older crater floor units exhibiting discontinuous inclined layering. Above the contact boundary are younger basal delta units exhibiting regular horizontal layering. At one location, there is a clear unconformity between the crater floor and delta layers, which implies that the crater floor experienced a period of erosion before the deposition of the overlying delta strata. The regularity and horizontality of the basal delta sediments observed in the radar cross sections indicate that they were deposited in a low-energy lake environment.

Percutaneous Electrical Nerve Field Stimulation in Children and Adolescents With Functional Dyspepsia-Integrating a Behavioral Intervention.

OBJECTIVES: Functional dyspepsia (FD) includes postprandial distress and epigastric pain syndrome. Percutaneous electrical nerve field stimulation (PENFS) in addition to behavioral interventions (BI) has shown benefits in children with functional abdominal pain but not specifically in FD. We aimed to assess the efficacy of PENFS for treating FD and compare the outcomes with those who received the combination of PENFS + BI. MATERIALS AND METHODS: Charts of patients with FD who completed four weeks of PENFS were evaluated. A subset of patients received concurrent BI. Demographic data, medical history, and symptoms were documented. Outcomes at different time points included subjective symptom responses and validated questionnaires collected clinically (Abdominal Pain Index [API], Nausea Severity Scale [NSS], Functional Disability Inventory [FDI], Pittsburgh Sleep Quality Index [PSQI], Children's Somatic Symptoms Inventory [CSSI], Patient-Reported Outcomes Measurement Information Systems [PROMIS] Pediatric Anxiety and Depression scales). RESULT: Of 84 patients, 61% received PENFS + BI, and 39% received PENFS alone. In the entire cohort, API (p < 0.0001), NSS (p = 0.001), FDI (p = 0.001), CSSI (p < 0.0001), PSQI (p = 0.01), PROMIS anxiety (p = 0.02), and depression (p = 0.01) scores improved from baseline to three weeks and at three months. Subjective responses showed nausea improvement (p = 0.01) and a trend for improvement in abdominal pain (p = 0.07) at week three. Abdominal pain subjectively improved at week three and three months (p = 0.003 and 0.02, respectively), nausea at week three and three months (p = 0.01 and 0.04, respectively), and a trend for improvement in sleep disturbances at week three and three months (p = 0.08 and p = 0.07, respectively) in the PENFS + BI group vs PENFS alone. CONCLUSION: Abdominal pain, nausea, functioning, somatization, sleep disturbances, anxiety, and depression improved at three weeks and three months after PENFS in pediatric FD. Subjective pain and nausea improvement were greater in the PENFS + BI group than in the group with PENFS alone, suggesting an additive effect of psychologic therapy.

Ground penetrating radar observations of subsurface structures in the floor of Jezero crater, Mars.

The Radar Imager for Mars Subsurface Experiment instrument has conducted the first rover-mounted ground-penetrating radar survey of the Martian subsurface. A continuous radar image acquired over the Perseverance rover's initial ~3-kilometer traverse reveals electromagnetic properties and bedrock stratigraphy of the Jezero crater floor to depths of ~15 meters below the surface. The radar image reveals the presence of ubiquitous strongly reflecting layered sequences that dip downward at angles of up to 15 degrees from horizontal in directions normal to the curvilinear boundary of and away from the exposed section of the Séitah formation. The observed slopes, thicknesses, and internal morphology of the inclined stratigraphic sections can be interpreted either as magmatic layering formed in a differentiated igneous body or as sedimentary layering commonly formed in aqueous environments on Earth. The discovery of buried structures on the Jezero crater floor is potentially compatible with a history of igneous activity and a history of multiple aqueous episodes.

Report of the Joint Workshop on Induced Special Regions.

The Joint Workshop on Induced Special Regions convened scientists and planetary protection experts to assess the potential of inducing special regions through lander or rover activity. An Induced Special Region is defined as a place where the presence of the spacecraft could induce water activity and temperature to be sufficiently high and persist for long enough to plausibly harbor life. The questions the workshop participants addressed were: (1) What is a safe stand-off distance, or formula to derive a safe distance, to a purported special region? (2) Questions about RTGs (Radioisotope Thermoelectric Generator), other heat sources, and their ability to induce special regions. (3) Is it possible to have an infected area on Mars that does not contaminate the rest of Mars? The workshop participants reached a general consensus addressing the posed questions, in summary: (1) While a spacecraft on the surface of Mars may not be able to explore a special region during the prime mission, the safe stand-off distance would decrease with time because the sterilizing environment, that is the martian surface would progressively clean the exposed surfaces. However, the analysis supporting such an exploration should ensure that the risk to exposing interior portions of the spacecraft (i.e., essentially unsterilized) to the martian surface is minimized. (2) An RTG at the surface of Mars would not create a Special Region but the short-term result depends on kinetics of melting, freezing, deliquescence, and desiccation. While a buried RTG could induce a Special Region, it would not pose a long-term contamination threat to Mars, with the possible exception of a migrating RTG in an icy deposit. (3) Induced Special Regions can allow microbial replication to occur (by definition), but such replication at the surface is unlikely to globally contaminate Mars. An induced subsurface Special Region would be isolated and microbial transport away from subsurface site is highly improbable.

Can an Off-Nominal Landing by an MMRTG-Powered Spacecraft Induce a Special Region on Mars When No Ice Is Present?

This work aims at addressing whether a catastrophic failure of an entry, descent, and landing event of a Multimission Radioisotope Thermoelectric Generator-based lander could embed the heat sources into the martian subsurface and create a local environment that (1) would temporarily satisfy the conditions for a martian Special Region and (2) could establish a transport mechanism through which introduced terrestrial organisms could be mobilized to naturally occurring Special Regions elsewhere on Mars. Two models were run, a primary model by researchers at the Lawrence Berkeley National Laboratory and a secondary model by researchers at the Jet Propulsion Laboratory, both of which were based on selected starting conditions for various surface composition cases that establish the worst-case scenario, including geological data collected by the Mars Science Laboratory at Gale Crater. The summary outputs of both modeling efforts showed similar results: that the introduction of the modeled heat source could temporarily create the conditions established for a Special Region, but that there would be no transport mechanism by which an introduced terrestrial microbe, even if it was active during the temporarily induced Special Region conditions, could be transported to a naturally occurring Special Region of Mars.

Active Boulder Movement at High Martian Latitudes.

Lobate stony landforms occur on steep slopes at high latitudes on Mars. We demonstrate active boulder movement at seven such sites. Submeter-scale boulders frequently move distances of a few meters. The movement is concentrated in the vicinity of the lobate landforms but also occurs on other slopes. This provides evidence for a newly discovered, common style of activity on Mars, which may play an important role in slope degradation. It also opens the possibility that the lobate features are currently forming in the absence of significant volumes of liquid water.

Sublimation of terrestrial permafrost and the implications for ice-loss processes on Mars.

Sublimation of ice is rate-controlled by vapor transport away from its outer surface and may have generated landforms on Mars. In ice-cemented ground (permafrost), the lag of soil particles remaining after ice loss decreases subsequent sublimation. Varying soil-ice ratios lead to differential lag development. Here we report 52 years of sublimation measurements from a permafrost tunnel near Fairbanks, Alaska, and constrain models of sublimation, diffusion through porous soil, and lag formation. We derive the first long-term in situ effective diffusion coefficient of ice-free loess, a Mars analog soil, of 9.05 × 10-6 m2 s-1, ~5× larger than past theoretical studies. Exposed ice-wedge sublimation proceeds ~4× faster than predicted from analogy to heat loss by buoyant convection, a theory frequently employed in Mars studies. Our results can be used to map near-surface ice-content differences, identify surface processes controlling landform formation and morphology, and identify target landing sites for human exploration of Mars.

Blocking HIV-1 Infection by Chromosomal Integrative Expression of Human CD4 on the Surface of Lactobacillus acidophilus ATCC 4356.

Lactobacillus bacteria are potential delivery vehicles for biopharmaceutical molecules because they are well-recognized as safe microorganisms that naturally inhabit the human body. The goal of this study was to employ these lactobacilli to combat human immunodeficiency virus type 1 (HIV-1) infection and transmission. By using a chromosomal integration method, we engineered Lactobacillus acidophilus ATCC 4356 to display human CD4, the HIV-1 receptor, on the cell surface. Since human CD4 can bind to any infectious HIV-1 particles, the engineered lactobacilli can potentially capture HIV-1 of different subtypes and prevent infection. Our data demonstrate that the CD4-carrying bacteria are able to adsorb HIV-1 particles and reduce infection significantly in vitro and also block intrarectal HIV-1 infection in a humanized mouse model in preliminary tests in vivo Our results support the potential of this approach to decrease the efficiency of HIV-1 sexual transmission.IMPORTANCE In the absence of an effective vaccine, alternative approaches to block HIV-1 infection and transmission with commensal bacteria expressing antiviral proteins are being considered. This report provides a proof-of-concept by using Lactobacillus bacteria stably expressing the HIV-1 receptor CD4 to capture and neutralize HIV-1 in vitro and in a humanized mouse model. The stable expression of antiviral proteins, such as CD4, following genomic integration of the corresponding genes into this Lactobacillus strain may contribute to the prevention of HIV-1 sexual transmission.

Exposed subsurface ice sheets in the Martian mid-latitudes.

Thick deposits cover broad regions of the Martian mid-latitudes with a smooth mantle; erosion in these regions creates scarps that expose the internal structure of the mantle. We investigated eight of these locations and found that they expose deposits of water ice that can be >100 meters thick, extending downward from depths as shallow as 1 to 2 meters below the surface. The scarps are actively retreating because of sublimation of the exposed water ice. The ice deposits likely originated as snowfall during Mars' high-obliquity periods and have now compacted into massive, fractured, and layered ice. We expect the vertical structure of Martian ice-rich deposits to preserve a record of ice deposition and past climate.

The effects of snow and salt on ice table stability in University Valley, Antarctica.

The Antarctic Dry Valleys represent a unique environment where it is possible to study dry permafrost overlaying an ice-rich permafrost. In this paper, two opposing mechanisms for ice table stability in University Valley are addressed: i) diffusive recharge via thin seasonal snow deposits andii) desiccation via salt deposits in the upper soil column. A high-resolution time-marching soil and snow model was constructed and applied to University Valley, driven by meteorological station atmospheric measurements. It was found that periodic thin surficial snow deposits (observed in University Valley) are capable of drastically slowing (if not completely eliminating) the underlying ice table ablation. The effects of NaCl, CaCl2 and perchlorate deposits were then modelled. Unlike the snow cover, however, the presence of salt in the soil surface (but no periodic snow) results in a slight increase in the ice table recession rate, due to the hygroscopic effects of salt sequestering vapour from the ice table below. Near-surface pore ice frequently forms when large amounts of salt are present in the soil due to the suppression of the saturation vapour pressure. Implications for Mars high latitudes are discussed.

The pH dependent reactions of graphene oxide with small molecule thiols.

Graphene oxide (GO) is a heterogenous 2D carbon-based material composed of sp2 and sp3 hybridized carbon atoms and oxygen containing functionalities, i.e., alcohols and epoxides. Thus, the chemical reactivity of GO is complex and both complimentary and contrasting to the reactivity of corresponding small molecules (e.g., tertiary alcohols, epoxides, and alkenes). Understanding the reactivity of GO under different conditions and with different reagents will ensure the chemical composition can be controlled and thus electronic and optical properties dictated, and solubility tuned for desired applications. Reaction of GO nanosheets towards a variety of reagents has been reported, however controlling the reaction pathway of GO nanosheets with a single nucleophile by simple alternation of the reaction medium has not been realized. This ability to tune the reaction by modification of solution pH, for example, would aid in understanding the reactivity of GO. Herein, we report that GO undergoes two distinct reaction pathways with ethane thiol depending on the pH of the reaction media: under aprotic basic conditions GO nanosheets undergo functionalization with minimal reduction, and under superacidic conditions GO nanosheets are reduced with no functionalization.

Escherichia coli surface display of single-chain antibody VRC01 against HIV-1 infection.

Human immunodeficiency virus type 1 (HIV-1) transmission and infection occur mainly via the mucosal surfaces. The commensal bacteria residing in these surfaces can potentially be employed as a vehicle for delivering inhibitors to prevent HIV-1 infection. In this study, we have employed a bacteria-based strategy to display a broadly neutralizing antibody VRC01, which could potentially be used to prevent HIV-1 infection. The VRC01 antibody mimics CD4-binding to gp120 and has broadly neutralization activities against HIV-1. We have designed a construct that can express the fusion peptide of the scFv-VRC01 antibody together with the autotransporter ß-barrel domain of IgAP gene from Neisseria gonorrhoeae, which enabled surface display of the antibody molecule. Our results indicate that the scFv-VRC01 antibody molecule was displayed on the surface of the bacteria as demonstrated by flow cytometry and immunofluorescence microscopy. The engineered bacteria can capture HIV-1 particles via surface-binding and inhibit HIV-1 infection in cell culture.

A new analysis of Mars "Special Regions": findings of the second MEPAG Special Regions Science Analysis Group (SR-SAG2).

A committee of the Mars Exploration Program Analysis Group (MEPAG) has reviewed and updated the description of Special Regions on Mars as places where terrestrial organisms might replicate (per the COSPAR Planetary Protection Policy). This review and update was conducted by an international team (SR-SAG2) drawn from both the biological science and Mars exploration communities, focused on understanding when and where Special Regions could occur. The study applied recently available data about martian environments and about terrestrial organisms, building on a previous analysis of Mars Special Regions (2006) undertaken by a similar team. Since then, a new body of highly relevant information has been generated from the Mars Reconnaissance Orbiter (launched in 2005) and Phoenix (2007) and data from Mars Express and the twin Mars Exploration Rovers (all 2003). Results have also been gleaned from the Mars Science Laboratory (launched in 2011). In addition to Mars data, there is a considerable body of new data regarding the known environmental limits to life on Earth-including the potential for terrestrial microbial life to survive and replicate under martian environmental conditions. The SR-SAG2 analysis has included an examination of new Mars models relevant to natural environmental variation in water activity and temperature; a review and reconsideration of the current parameters used to define Special Regions; and updated maps and descriptions of the martian environments recommended for treatment as "Uncertain" or "Special" as natural features or those potentially formed by the influence of future landed spacecraft. Significant changes in our knowledge of the capabilities of terrestrial organisms and the existence of possibly habitable martian environments have led to a new appreciation of where Mars Special Regions may be identified and protected. The SR-SAG also considered the impact of Special Regions on potential future human missions to Mars, both as locations of potential resources and as places that should not be inadvertently contaminated by human activity.

Dietary docosahexaenoic acid supplementation in children with autism.

OBJECTIVE: The aim of the study was to determine whether docosahexaenoic acid (DHA) supplementation improves the behavior of children with autism. METHODS: A group of 3- to 10-year-old children with autism were randomized in a double-blind fashion to receive a supplement containing 200 mg of DHA or a placebo for 6 months. The parents and the investigator completed the Clinical Global Impressions-Improvement scale to rate changes in core symptoms of autism after 3 and 6 months. The parents completed the Child Development Inventory and the Aberrant Behavior Checklist, and both parents and teachers completed the Behavior Assessment Scale for Children (BASC) at enrollment and after 6 months. RESULTS: A total of 48 children (40 [83%] boys, mean age [standard deviation] 6.1 [2.0] years) were enrolled; 24 received DHA and 24 placebo. Despite a median 431% increase in total plasma DHA levels after 6 months, the DHA group was not rated as improved in core symptoms of autism compared to the placebo group on the CGI-I. Based on the analysis of covariance models adjusted for the baseline rating scores, parents (but not teachers) provided a higher average rating of social skills on the BASC for the children in the placebo group compared to the DHA group (P = 0.04), and teachers (but not parents) provided a higher average rating of functional communication on the BASC for the children in the DHA group compared to the placebo group (P = 0.02). CONCLUSIONS: Dietary DHA supplementation of 200 mg/day for 6 months does not improve the core symptoms of autism. Our results may have been limited by inadequate sample size.

The clinical utility of health-related quality of life screening in a pediatric inflammatory bowel disease clinic.

BACKGROUND: Adjusting to symptom flares, treatment regimens, and side effects places youth with inflammatory bowel disease (IBD) at increased risk for emotional and behavioral problems and adverse disease outcomes. Implementation of psychosocial screening into clinical practice remains a challenge. This study examines the clinical utility of health-related quality of life (HRQOL) screening in predicting disease outcome and healthcare utilization. METHODS: One hundred twelve youth of 7 to 18 years diagnosed with IBD and their parents. Youth completed standardized measures of HRQOL and depression. Parents completed a proxy report of HRQOL. Pediatric gastroenterologists provided the Physician Global Assessment. Families were recruited from a pediatric gastroenterology clinic. Retrospective chart reviews examined disease outcome and healthcare utilization for 12 months after baseline measurement. RESULTS: Linear regressions, controlling for demographic and disease parameters, revealed that baseline measurement of youth and parent proxy-reported HRQOL predicted the number of IBD-related hospital admissions, gastroenterology clinic visits, emergency department visits, psychology clinic visits, telephone contacts, and pain management referrals over the next 12 months. Disease outcome was not significant. CONCLUSIONS: Lower HRQOL was predictive of increased healthcare utilization among youth with IBD. Regular HRQOL screening may be the impetus to providing better case management and allocating resources based on ongoing care needs and costs. Proactive interventions focused on patients with poor HRQOL may be an efficient approach to saving on healthcare costs and resource utilization.

Incidence of enuresis and encopresis among children with attention-deficit/hyperactivity disorder in a population-based birth cohort.

OBJECTIVE: This study reports the incidence of enuresis and encopresis among children with attention-deficit/hyperactivity disorder (ADHD) versus those without ADHD. METHODS: Subjects included 358 children (74.5% boys) with research-identified ADHD from a 1976 to 1982 population-based birth cohort (n = 5718) and 729 (75.2% boys) non-ADHD control subjects from the same birth cohort, matched by gender and age. All subjects were retrospectively followed from birth until a diagnosis of enuresis or encopresis was made or last follow-up before 18 years of age. The complete medical record for each subject was reviewed to obtain information on age of initial diagnosis of an elimination disorder, frequency and duration of symptoms, and identification of exclusionary criteria specified by DSM-IV, with confirmation of the diagnosis by expert consensus. RESULTS: Children with ADHD were 2.1 (95% confidence interval [CI], 1.3-3.4; P = .002) times more likely to meet DSM-IV criteria for enuresis than non-ADHD controls; they were 1.8 (95% CI, 1.2-2.7; P = .006) times more likely to do so than non-ADHD controls when less stringent criteria for a diagnosis of enuresis were employed. Though not significant, children with ADHD were 1.8 (95% CI, 0.7-4.6; P = .23) times more likely to meet criteria for encopresis than non-ADHD controls. The relative risk was 2.0 (95% CI, 1.0-4.1; P = .05) when a less stringent definition for encopresis was utilized. CONCLUSIONS: Children with ADHD are more likely than their peers without ADHD to develop enuresis with a similar trend for encopresis.

Daily or intermittent budesonide in preschool children with recurrent wheezing.

BACKGROUND: Daily inhaled glucocorticoids are recommended for young children at risk for asthma exacerbations, as indicated by a positive value on the modified asthma predictive index (API) and an exacerbation in the preceding year, but concern remains about daily adherence and effects on growth. We compared daily therapy with intermittent therapy. METHODS: We studied 278 children between the ages of 12 and 53 months who had positive values on the modified API, recurrent wheezing episodes, and at least one exacerbation in the previous year but a low degree of impairment. Children were randomly assigned to receive a budesonide inhalation suspension for 1 year as either an intermittent high-dose regimen (1 mg twice daily for 7 days, starting early during a predefined respiratory tract illness) or a daily low-dose regimen (0.5 mg nightly) with corresponding placebos. The primary outcome was the frequency of exacerbations requiring oral glucocorticoid therapy. RESULTS: The daily regimen of budesonide did not differ significantly from the intermittent regimen with respect to the frequency of exacerbations, with a rate per patient-year for the daily regimen of 0.97 (95% confidence interval [CI], 0.76 to 1.22) versus a rate of 0.95 (95% CI, 0.75 to 1.20) for the intermittent regimen (relative rate in the intermittent-regimen group, 0.99; 95% CI, 0.71 to 1.35; P=0.60). There were also no significant between-group differences in several other measures of asthma severity, including the time to the first exacerbation, or adverse events. The mean exposure to budesonide was 104 mg less with the intermittent regimen than with the daily regimen. CONCLUSIONS: A daily low-dose regimen of budesonide was not superior to an intermittent high-dose regimen in reducing asthma exacerbations. Daily administration led to greater exposure to the drug at 1 year. (Funded by the National Heart, Lung, and Blood Institute and others; MIST ClinicalTrials.gov number, NCT00675584.).

Test for Respiratory and Asthma Control in Kids (TRACK): clinically meaningful changes in score.

BACKGROUND: The Test for Respiratory and Asthma Control in Kids (TRACK) is the first validated questionnaire to assess respiratory and asthma control exclusively in young children. OBJECTIVE: We sought to determine the minimally important difference (MID) for interpreting meaningful changes in individual patients' TRACK scores. METHODS: In this prospective, nonrandomized, longitudinal study conducted at 20 US pediatric sites, TRACK was administered at 2 separate clinic visits (4-6 weeks apart) to caregivers of children aged less than 5 years with symptoms consistent with asthma. Anchor-based methods were used to determine the MID from mean score differences between patients based on multiple criteria measures: physician guidelines-based respiratory control rating, physician-recommended changes to therapy, episodes of symptoms lasting more than 24 hours in the past 3 months, oral corticosteroid use for respiratory tract illnesses in the past year, physician-assessed change in control status at follow-up, and caregiver-reported change in respiratory status. The MID also was determined from distribution-based methods. RESULTS: TRACK scores were assessed at baseline (426 caregivers) and follow-up (396 caregivers). Mean differences in TRACK scores between patients differing on criteria measures ranged from 3.4 to 16.4 points (mean, 11.1 points). Distribution-based techniques confirmed these findings. Based on logistic regression analyses, scoring 10 or more points less than 80 on TRACK was associated with an approximately 2-fold increased odds of having uncontrolled asthma or respiratory symptoms. CONCLUSION: Changes in TRACK scores of 10 or more points represent clinically meaningful changes in respiratory control status in individual young children with respiratory symptoms consistent with asthma and should alert health care providers to re-evaluate asthma management.

Massive CO2 ice deposits sequestered in the south polar layered deposits of Mars.

Shallow Radar soundings from the Mars Reconnaissance Orbiter reveal a buried deposit of carbon dioxide (CO(2)) ice within the south polar layered deposits of Mars with a volume of 9500 to 12,500 cubic kilometers, about 30 times that previously estimated for the south pole residual cap. The deposit occurs within a stratigraphic unit that is uniquely marked by collapse features and other evidence of interior CO(2) volatile release. If released into the atmosphere at times of high obliquity, the CO(2) reservoir would increase the atmospheric mass by up to 80%, leading to more frequent and intense dust storms and to more regions where liquid water could persist without boiling.