The formation of Charon's red poles from seasonally cold-trapped volatiles.

A unique feature of Pluto's large satellite Charon is its dark red northern polar cap. Similar colours on Pluto's surface have been attributed to tholin-like organic macromolecules produced by energetic radiation processing of hydrocarbons. The polar location on Charon implicates the temperature extremes that result from Charon's high obliquity and long seasons in the production of this material. The escape of Pluto's atmosphere provides a potential feedstock for a complex chemistry. Gas from Pluto that is transiently cold-trapped and processed at Charon's winter pole was proposed as an explanation for the dark coloration on the basis of an image of Charon's northern hemisphere, but not modelled quantitatively. Here we report images of the southern hemisphere illuminated by Pluto-shine and also images taken during the approach phase that show the northern polar cap over a range of longitudes. We model the surface thermal environment on Charon and the supply and temporary cold-trapping of material escaping from Pluto, as well as the photolytic processing of this material into more complex and less volatile molecules while cold-trapped. The model results are consistent with the proposed mechanism for producing the observed colour pattern on Charon.

Morphometric variation in bluegill Lepomis macrochirus and green sunfish Lepomis cyanellus in lentic and lotic systems.

Bluegill Lepomis macrochirus and green sunfish Lepomis cyanellus were examined using geometric morphometrics to evaluate the variation in morphology between fishes that reside in lentic (e.g. lakes) and lotic (e.g. streams) ecosystems. Live fishes were collected from reservoirs and rivers in central Indiana, while additional fishes were sampled from museum collections at Ball State University and the Illinois Natural History Survey. Male and female L. macrochirus and female L. cyanellus from lentic systems display a deeper body than those from lotic systems, while no differences were found in male L. cyanellus morphometry. A deeper body promotes greater manoeuverability, typically desirable in lentic systems. In contrast, the more streamlined body of the fishes found in lotic systems reduces drag as it contends with flowing water, ultimately maximizing energy efficiency. The absence of morphological differences, such as those found in male L. cyanellus, may be caused by fish occupying both lentic and lotic systems, from the population not having been present in the body of water long enough to display any adaptations, or from a lack of statistical power caused by the small sample size.

Nationwide benthic macroinvertebrate assemblage multimetric indices: identifying inconsistencies and limitations in reporting stream impairment status, USA.

The objective of this study was to identify the current status of stream water-quality assessment and reporting methods for four states in the Ohio River basin (Indiana, Ohio, Tennessee, and Virginia), as required by the 305(b) section of the United States (US) Clean Water Act. Specifically, we clarified the discrepancies that exist among stream-impairment status classified by benthic macroinvertebrate multimetric indices (MMIs) and depicted using Geographic Information Systems shapefiles. In addition, we provided guidance in solving some of the comparability problems that arise when developing state-specific MMIs and depicting stream-impairment status using Geographic Information Systems technology. The MMI variation among states and differences in shapefile formats resulted in a nationwide dataset, which cannot be directly compared. Incorporating the changes suggested in this study allow for a uniform assessment and reporting method nationwide. Successful implementation of these changes would strengthen the US Environmental Protection Agency efforts to identify impaired streams and sources of those impairments without the limitations of state-by-state .developed assessment methods.

Gravity resonance spectroscopy constrains dark energy and dark matter scenarios.

We report on precision resonance spectroscopy measurements of quantum states of ultracold neutrons confined above the surface of a horizontal mirror by the gravity potential of Earth. Resonant transitions between several of the lowest quantum states are observed for the first time. These measurements demonstrate that Newton's inverse square law of gravity is understood at micron distances on an energy scale of 10-14 eV. At this level of precision, we are able to provide constraints on any possible gravitylike interaction. In particular, a dark energy chameleon field is excluded for values of the coupling constant ß>5.8×108 at 95% confidence level (C.L.), and an attractive (repulsive) dark matter axionlike spin-mass coupling is excluded for the coupling strength gsgp>3.7×10-16 (5.3×10-16) at a Yukawa length of λ=20 µm (95% C.L.).

Impaired red blood cell deformability in patients with coronary artery disease and diabetes mellitus.

Patients with diabetes mellitus (DM) have an increased cardiovascular morbidity and mortality. There is increasing evidence that diabetes mellitus is associated with pathological hemorheological alterations, which might contribute to impaired coronary blood flow in coronary artery disease (CAD). We hypothesize that red blood cell (RBC) deformability is impaired in diabetic patients with CAD in comparison to nondiabetic patients with CAD. RBC deformability was measured in 21 patients with CAD and type 2 diabetes mellitus (CAD + DM) and 24 patients with CAD (CAD - DM). RBC deformability was measured by the Laser-assisted optical rotational cell analyzer by determining the elongation index (EI). RBC deformability was reduced in patients with CAD + DM in comparison to patients with CAD - DM (EI @ 1.12 Pa 0.236 ± 0.008 vs. 0.260 ± 0.005, p=0.007). Inverse univariate correlations were found between the EI @ 1.12 Pa and plasma glucose concentration (r= - 0.57; p<0.001) and HbA1c (r= - 0.45; p=0.002). Multivariate linear regression analysis identified plasma glucose concentration as the independent predictor of RBC deformability (ß= - 0.58; p=0.007) thereby indicating that increased glucose concentrations determine RBC deformability in diabetic patients with CAD. In patients with CAD, diabetes mellitus leads to an impairment of RBC deformability which might contribute to increased morbidity of diabetic patients with CAD.

Modulation of peripheral chemoreflex by neurohumoral adaptations after kidney transplantation.

BACKGROUND: Peripheral chemoreceptors residing predominantly in the carotid body monitor changes in arterial blood oxygen and are mechanistically linked to the cardiorespiratory control by the autonomic nervous system. Enhanced sympathetic activation is common in end-stage renal disease and kidney transplantation has been shown to improve cardiorespiratory reflex measures of autonomic function. OBJECTIVE: The aim of the present study was to test whether improvement in renal function following kidney transplantation is related to an improvement in chemosensory function. METHODS AND RESULTS: We compared hyperoxic chemoreflex sensitivity (CHRS) in patients after renal transplantation (RTX) to that in patients on maintenance hemodialysis (HD), and that of age- and gender-matched healthy controls. In addition, we investigated the impact of common confounding factors including pharmacological neurohumoral modulation and diabetes mellitus. The difference in the R-R intervals divided by the difference in the oxygen pressures before and after deactivation of the chemoreceptors by 5-min inhalation of 7 L oxygen was calculated as the hyperoxic CHRS. Autonomic activity was characterized by 24-h time-domain heart rate variability (HRV) parameters. CHRS was improved in RTX patients as compared to HD patients being related to HRV. CHRS was related to the concomitant presence of diabetes and medication with cyclosporine. CONCLUSION: Our findings indicate that chemosensory activity following kidney transplantation is related to cardiac autonomic control, but functional testing might only be useful to characterize the time course and extent of sympathetic activation in selected patients due to existing co-morbidities and immunosuppressive medication in this population.

The solar nebula origin of (486958) Arrokoth, a primordial contact binary in the Kuiper Belt.

The New Horizons spacecraft's encounter with the cold classical Kuiper Belt object (486958) Arrokoth (provisional designation 2014 MU69) revealed a contact-binary planetesimal. We investigated how Arrokoth formed and found that it is the product of a gentle, low-speed merger in the early Solar System. Its two lenticular lobes suggest low-velocity accumulation of numerous smaller planetesimals within a gravitationally collapsing cloud of solid particles. The geometric alignment of the lobes indicates that they were a co-orbiting binary that experienced angular momentum loss and subsequent merger, possibly because of dynamical friction and collisions within the cloud or later gas drag. Arrokoth's contact-binary shape was preserved by the benign dynamical and collisional environment of the cold classical Kuiper Belt and therefore informs the accretion processes that operated in the early Solar System.

The geology and geophysics of Kuiper Belt object (486958) Arrokoth.

The Cold Classical Kuiper Belt, a class of small bodies in undisturbed orbits beyond Neptune, is composed of primitive objects preserving information about Solar System formation. In January 2019, the New Horizons spacecraft flew past one of these objects, the 36-kilometer-long contact binary (486958) Arrokoth (provisional designation 2014 MU69). Images from the flyby show that Arrokoth has no detectable rings, and no satellites (larger than 180 meters in diameter) within a radius of 8000 kilometers. Arrokoth has a lightly cratered, smooth surface with complex geological features, unlike those on previously visited Solar System bodies. The density of impact craters indicates the surface dates from the formation of the Solar System. The two lobes of the contact binary have closely aligned poles and equators, constraining their accretion mechanism.

Sympathetic hyperactivity influences chemosensor function in patients with end-stage renal disease.

BACKGROUND: Autonomic neuropathy is common in patients suffering from end-stage renal disease (ESRD). This may in part explain the high cardiovascular mortality in these patients. Chemosensory function is involved in autonomic cardiovascular control and is mechanistically linked to the sympathetic tone. OBJECTIVE: The aim of the present study was to assess whether sympathetic hyperactivity contributes to an altered chemosensory function in ESRD. MATERIAL AND METHODS: In a randomized, double-masked, placebo controlled crossover design we studied the impact of chemosensory deactivation on heart rate, blood pressure and oxygen saturation in 10 ESRD patients and 10 age and gender matched controls. The difference in the R-R intervals divided by the difference in the oxygen pressures before and after deactivation of the chemoreceptors by 5-min inhalation of 7 L oxygen was calculated as the hyperoxic chemoreflex sensitivity (CHRS). Placebo consisted of breathing room air. Baseline sympathetic activity was characterized by plasma catecholamine levels and 24-h time-domain heart rate variability (HRV) parameters. RESULTS: Plasma norepinephrine levels were increased (1.6 +/- 0.4 vs. 5.8 +/- 0.6; P<0.05) while the SDNN (standard deviation of all normal R-R intervals: 126.4 +/- 19 vs. 100.2 +/- 12 ms), the RMSSD (square root of the mean of the squared differences between adjacent normal R-R intervals: 27.1 +/- 8 vs. 15.7 +/- 2 ms), and the 24-h triangular index (33.6 +/- 4 vs. 25.7 +/- 3; each P<0.05) were decreased in ESRD patients as compared to controls. CHRS was impaired in ESRD patients (2.9 +/- 0.9 ms/mmHg, P<0.05) as compared to controls (7.9 +/- 1.4 ms/mmHg). On multiple regression analysis 24 h-Triangular index, RMSSD, and plasma norepinephrine levels were independent predictors of an impaired hyperoxic CHRS. CONCLUSION: Sympathetic hyperactivity influences chemosensory function in ESRD resulting in an impaired hyperoxic CHRS.

Impact craters on Pluto and Charon indicate a deficit of small Kuiper belt objects.

The flyby of Pluto and Charon by the New Horizons spacecraft provided high-resolution images of cratered surfaces embedded in the Kuiper belt, an extensive region of bodies orbiting beyond Neptune. Impact craters on Pluto and Charon were formed by collisions with other Kuiper belt objects (KBOs) with diameters from ~40 kilometers to ~300 meters, smaller than most KBOs observed directly by telescopes. We find a relative paucity of small craters ≲13 kilometers in diameter, which cannot be explained solely by geological resurfacing. This implies a deficit of small KBOs (≲1 to 2 kilometers in diameter). Some surfaces on Pluto and Charon are likely ≳4 billion years old, thus their crater records provide information on the size-frequency distribution of KBOs in the early Solar System.

L-arginine preferentially dilates stenotic segments of coronary arteries thereby increasing coronary flow.

BACKGROUND AND OBJECTIVES: Oxidized LDL cholesterol and cytokines increase arginase and decrease nitric oxide (NO) synthase expression in human endothelial cells, leading to a decrease in NO production. In arteriosclerotic plaques, characterized by increased oxidized LDL and cytokine levels, a sustained local NO reduction might enhance sensitivity of the downstream guanylyl cyclase system towards an acute NO increase. We tested whether application of the NO synthase substrate l-arginine (l-arg, 150 micromol min(-1)) or the NO donor isosorbide dinitrate (ISDN; 0.3 mg) preferentially dilates stenotic coronary artery segments (CS) subsequently increasing poststenotic coronary blood flow (CBF) in patients with coronary artery disease (CAD). DESIGN, SETTING AND SUBJECTS: Changes in coronary diameter and circumferential surface area were assessed by quantitative coronary angiography (QCA) in a nonstenotic upstream segment, the CS, downstream the CS and in a reference vessel (n = 24). CBF was estimated in a subset of 13 patients by QCA and intracoronary Doppler. RESULTS: CS ranged from 62% to 89% (77 +/- 5%). l-arg increased minimal luminal diameter of the stenotic segment from 0.98 +/- 0.06 to 1.14 +/- 0.07 mm (P < 0.05) without affecting other coronary segments. Poststenotic CBF increased by 24 +/- 3%. ISDN dilated all segments again with a predominance of CS (25 +/- 4%) and increased poststenotic CBF by 38 +/- 9%. In a multifactorial anova, a medication with an angiotensin-converting enzyme inhibitor (decreasing inflammation and radical formation) and a ratio of LDL/HDL <3.5 were predictive for an l-arg-induced dilation. CONCLUSION: The increase in poststenotic CBF without affecting nondiseased arteries highlights the therapeutic potential of l-arg in patients with CAD.

"One-stop-shop" ultrasound diagnosis of functional, structural and physicomechanical properties of the brachial artery.

BACKGROUND: The pathogenesis of atherosclerosis comprises endothelial dysfunction, thickening as well as impaired compliance of the arterial vessel wall. Early assessment of these alterations of the vessel wall at the same site of the vascular tree has yet been hampered by the lack of highly sensitive diagnostic approaches suitable for clinical routine. We therefore aimed to develop and validate a single non-invasive examination of the brachial artery for simultaneous and highly accurate measurement of functional, structural and physicomechanical parameters of the brachial artery. PATIENTS AND METHODS: 20 healthy individuals were investigated using high resolution ultrasound. Flow-mediated dilation (FMD), fractional diameter changes (FDC) and intima-media-thickness (IMT) were measured in the same segment of the brachial artery. Coefficients of variation, day-to-day-variability, between- and within-observer-variability were investigated in 5 individuals. All measurements were performed manually and by an automated PC-based analyzing system. RESULTS: Mean values for all measured parameters were 7.65 +/- 0.8% for FMD, 0.02 +/- 0.002 for FDC, 0.351 +/- 0.007 mm for IMT and followed an even distribution throughout the study population. Automated analysis of coefficient of variation, day-to-day-, between- and within-observer variabilities were: 0. 78%, 1.3%, 0.8%, 0.8% (FMD); 4.7%, 2.8%, 4.2%, 2.7% (FDC); 1.8%, 1.1%, 1.9%, 1.1% (IMT). Coefficient of variation, day-to-day-, between- and within-observer variabilities for the manual readings were significantly higher. CONCLUSIONS: Functional, structural and physicomechanical parameters of the brachial artery can be quantified consecutively, time-saving and highly reproducibly as an "one-stop-shop" in a single session using high resolution ultrasound with digitized post-processing. This highlights the future possibility of early, sensitive and non-invasive diagnostic testing of vascular function in patients prone to vascular disease.

The small satellites of Pluto as observed by New Horizons.

The New Horizons mission has provided resolved measurements of Pluto's moons Styx, Nix, Kerberos, and Hydra. All four are small, with equivalent spherical diameters of ~40 kilometers for Nix and Hydra and ~10 kilometers for Styx and Kerberos. They are also highly elongated, with maximum to minimum axis ratios of ~2. All four moons have high albedos (~50 to 90%) suggestive of a water-ice surface composition. Crater densities on Nix and Hydra imply surface ages of at least 4 billion years. The small moons rotate much faster than synchronous, with rotational poles clustered nearly orthogonal to the common pole directions of Pluto and Charon. These results reinforce the hypothesis that the small moons formed in the aftermath of a collision that produced the Pluto-Charon binary.

Survival trends in adolescents with human immunodeficiency virus infection.

OBJECTIVE: To examine trends in survival and death in nonhemophiliac adolescents with human immunodeficiency virus (HIV) infection. DESIGN: Case series. SUBJECTS: All 117 HIV-seropositive adolescents (age range, 13 to 21 years) without hemophilia whose cases were reported through December 1992. SETTING: A state with mandatory, name-linked reporting of cases of HIV. METHODS: Review of death certificates and public records, and interviews with subjects and key informants. ANALYSES: Kaplan-Meier and Cox proportional hazards regression analyses of time from the diagnosis of HIV infection to death. RESULTS: Documentation of death or survival was available for 92% (108/117) of the sample. Fourteen percent (15/108) of the subjects were known to have died, mainly of well-recognized complications of acquired immunodeficiency syndrome. Among deceased subjects, the median duration of survival after the diagnosis of HIV was 3 years. Cumulative survival at 8 years after the diagnosis was 52%, with 4 years being the median period of observation (range, < 1 year to 8 years). Stratification of survival functions by gender, race, and mode of transmission revealed no significant (P < .05) differences between groups. However, advancing age at the time of the diagnosis was inversely associated with survival. CONCLUSIONS: Despite an apparent advantage to young age, overall survival in this adolescent cohort was shorter than expected. Rather than an inherently rapid progression of disease during adolescence, delays in diagnosis and treatment might better explain the results.

Use of the equity implementation model to review clinical system implementation efforts: a case report.

This paper presents the equity implementation model (EIM) in the context of a case that describes the implementation of a medical scheduling system. The model is based on equity theory, a well-established theory in the social sciences that has been tested in hundreds of experimental and field studies. The predictions of equity theory have been supported in organizational, societal, family, and other social settings. Thus, the EIM helps provide a theory-based understanding for collecting and reviewing users' reactions to, and acceptance or rejection of, a new technology or system. The case study (implementation of a patient scheduling and appointment setting system in a large health maintenance organization) illustrates how the EIM can be used to examine users' reactions to the implementation of a new system.

The health and psychosocial status of HIV-seropositive youth in Minnesota.

OBJECTIVE: To describe the health outcomes and health care utilization of nonhemophiliac adolescents diagnosed with human immunodeficiency virus (HIV) infection. DESIGN: Cross-sectional survey. SUBJECTS: All state residents without hemophilia, 13-21 years of age at the time of HIV infection diagnosis, reported to the Department of Health through April 1992. SETTING: A state where HIV and acquired immune deficiency syndrome (AIDS) are reportable conditions. METHODS: Structured interviews. RESULTS: The survey response rate was 67%. Most subjects reported preexisting and current psychosocial problems. In 35% of cases, subjects did not recall giving consent for HIV antibody testing; and many reported that seropositive results were delivered inappropriately. Eighty-seven percent of subjects reported recent medical care, without statistically significant differences related to gender, race, or mode of transmission. Within 3.5 years (median) of the diagnosis of HIV infection, 55% of participants reported having physical limitations that were found only to be associated with duration of illness. CONCLUSIONS: The findings highlight the need for better understanding of the progression and comorbidities of HIV disease during adolescence, counseling and testing practices, and expanded access to supportive services.

The irreducible ovary: a true emergency.

The management of a child with an irreducible ovary remains inconsistent in pediatric surgical centers. An informal survey of senior pediatric surgeons and an extensive review of the literature showed a prevailing view that the trapped ovary is not at significant risk of vascular compromise. Two recent cases prompted a review of our experience from 1984 to 1989, during which 1,699 children with inguinal hernias underwent operation, 386 (23%) of whom were girls. Fifteen girls (4%) had irreducible ovaries present at the time of operation and in 4 of the 15 (27%) the ovary was twisted and infarcted. Two of the 4 girls were known to have an irreducible ovary prior to the day of operation--1 was noted 2 months earlier and 1 was noted 1 month earlier. At the time of the initial diagnosis, neither patient had physical findings of vascular compromise of the ovary. In the other two girls, evidence of an infarcted ovary was present when the hernia was first diagnosed and an emergency operation was performed. A 27% incidence of torsion and strangulation of irreducible ovaries appears to be high, but reports of strangulated ovaries have been reported in 2% to 33% of other series. The normal anatomy is altered when an ovary is trapped in a hernia sac, and these changes make torsion more likely. Although an irreducible ovary is not at great risk of compression of its blood supply, this report identifies a significant risk of torsion. This risk warrants treating the asymptomatic irreducible ovary as any other incarcerated hernia--as a true emergency.

A magnetically shielded room with ultra low residual field and gradient.

A versatile and portable magnetically shielded room with a field of (700 ± 200) pT within a central volume of 1 m × 1 m × 1 m and a field gradient less than 300 pT/m, achieved without any external field stabilization or compensation, is described. This performance represents more than a hundredfold improvement of the state of the art for a two-layer magnetic shield and provides an environment suitable for a next generation of precision experiments in fundamental physics at low energies; in particular, searches for electric dipole moments of fundamental systems and tests of Lorentz-invariance based on spin-precession experiments. Studies of the residual fields and their sources enable improved design of future ultra-low gradient environments and experimental apparatus. This has implications for developments of magnetometry beyond the femto-Tesla scale in, for example, biomagnetism, geosciences, and security applications and in general low-field nuclear magnetic resonance (NMR) measurements.

Epidemiology and control of tuberculosis in Victoria, a low-burden state in south-eastern Australia, 2005-2010.

SETTING: Victoria, Australia. OBJECTIVE: To describe the epidemiology and control of tuberculosis (TB) in Victoria, 2005-2010. DESIGN: Retrospective review of laboratory-confirmed TB in Victoria, 2005-2010. State TB reference laboratory records were matched with Department of Health notification records to obtain laboratory, demographic, clinical and treatment data. RESULTS: The incidence of TB fell in the Australian-born population but increased overall, reflecting an increase in the proportion of overseas-born cases from 88.9% to 95.8% between 2005 and 2010 (P = 0.03). Patients from India and Viet Nam accounted for over one third of all cases. For overseas-born cases, the median time between arrival and diagnosis was 4 years. Half of all diagnoses were pulmonary disease, of which 45.4% were Ziehl-Neelsen smear-positive. Treatment was most commonly self-administered (76.9%), and very few patients defaulted or failed treatment (1.1%). Only 4.1% of cases were linked to another laboratory-confirmed case. Multidrug-resistant TB remained uncommon (1.7% of cases). CONCLUSIONS: TB in Victoria remains low by global standards and continues to overwhelmingly affect the overseas-born population. Current TB control strategies in Victoria are effective, but strengthened control in high-burden countries will also improve TB control locally.