Fermionic order by disorder in a van der Waals antiferromagnet.

CeTe3 is a unique platform to investigate the itinerant magnetism in a van der Waals (vdW) coupled metal. Despite chemical pressure being a promising route to boost quantum fluctuation in this system, a systematic study on the chemical pressure effect on Ce3+(4f1) states is absent. Here, we report on the successful growth of a series of Se doped single crystals of CeTe3. We found a fluctuation driven exotic magnetic rotation from the usual easy-axis ordering to an unusual hard-axis ordering. Unlike in localized magnetic systems, near-critical magnetism can increase itinerancy hand-in-hand with enhancing fluctuation of magnetism. Thus, seemingly unstable hard-axis ordering emerges through kinetic energy gain, with the self-consistent observation of enhanced magnetic fluctuation (disorder). As far as we recognize, this order-by-disorder process in fermionic system is observed for the first time within vdW materials. Our finding opens a unique experimental platform for direct visualization of the rich quasiparticle Fermi surface deformation associated with the Fermionic order-by-disorder process. Also, the search for emergent exotic phases by further tuning of quantum fluctuation is suggested as a promising future challenge.

Multiple surface wetting events in the greater Meridiani Planum region, Mars: Evidence from valley networks within ancient cratered highlands.

Morphological characterization of valley networks in three exposures of ancient cratered highlands (Nhc1) in the greater Meridiani Planum region yields insight into the Martian aqueous history. From our mapping, key regional differences are apparent in fine-scale valley network attributes including morphologic type, planimetric form, density, and links to candidate paleolakes. This information, combined with crater retention age (inferred exposure age), provides new details on the relative timing and nature of aqueous processes in the region. Newly identified pitted-type valley networks have morphological similarity to terrestrial pitted landforms in an evaporite setting. We interpret the pitted valley networks to reflect late-stage groundwater processes concentrated along the former fluvial conduits. Evidence from this study indicates that localized reactivation of valley networks occurred during or after exhumation of eastern Nhc1 unit.

The incidence of inguinal hernia and associated risk factors of incarceration in pediatric inguinal hernia: a nation-wide longitudinal population-based study.

PURPOSE: This study uses a national database to evaluate the incidence of inguinal hernia and associated risk factors of incarcerated hernia in children from birth to 15 years of age. METHODS: The study selected children born from 1997 to 2005 from a randomly selected cohort of 1,000,000 from an insured population of 23 million. We regarded children that were classified with code 550 and hernia surgery in accordance to the International Classification of Diseases, 9th Revision, as having inguinal hernia. We used the 2 chi-square test and logistic regression modeling for statistical analyses. RESULTS: In total, 79,794 children (41,767 male and 38,027 female) were enrolled in the study. The cumulative incidence of inguinal hernia in males and females from birth to 15 years old were 6.62 and 0.74 %, respectively (p < 0.01). The peak incidence of inguinal hernia was at 0 years of age for males and 5 years of age for females. The ratio of unilateral vs. bilateral repair was 5.54:1. Females tend to have more bilateral inguinal hernia than males (25.4 vs. 12.9 %, p < 0.01). Incarcerated hernia occurred in 4.19 % children with inguinal hernia without significant gender discrepancy. Approximately 40 % of incarcerated hernia underwent hernia repair immediately after visiting the emergent department. In patients who presented with reducible hernia, we did not find significant correlation between waiting time to hernia repair and occurrence of incarceration. CONCLUSIONS: The cumulative incidence of inguinal hernia from birth to 15 years of age was 6.62 and 0.74 % in males and females, respectively. Incarceration was not related to prematurity or the waiting time for surgery.

A closer look at water-related geologic activity on Mars.

Water has supposedly marked the surface of Mars and produced characteristic landforms. To understand the history of water on Mars, we take a close look at key locations with the High-Resolution Imaging Science Experiment on board the Mars Reconnaissance Orbiter, reaching fine spatial scales of 25 to 32 centimeters per pixel. Boulders ranging up to approximately 2 meters in diameter are ubiquitous in the middle to high latitudes, which include deposits previously interpreted as finegrained ocean sediments or dusty snow. Bright gully deposits identify six locations with very recent activity, but these lie on steep (20 degrees to 35 degrees) slopes where dry mass wasting could occur. Thus, we cannot confirm the reality of ancient oceans or water in active gullies but do see evidence of fluvial modification of geologically recent mid-latitude gullies and equatorial impact craters.