On wind-driven electrojets at magnetic cusps in the nightside ionosphere of Mars

Mars has a complex magnetic topology where crustal magnetic fields can interact with the solar wind magnetic field to form magnetic cusps. On the nightside, solar wind electron precipitation can produce enhanced ionization at cusps while closed field regions adjacent to cusps can be devoid of significant ionization. Using an electron transport model, we calculate the spatial structure of the nightside ionosphere of Mars using Mars Global Surveyor electron measurements as input. We find that localized regions of enhanced ionospheric density can occur at magnetic cusps adjacent to low density regions. Under this configuration, thermospheric winds can drive ionospheric electrojets. Collisional ions move in the direction of the neutral winds while magnetized electrons move perpendicular to the wind direction. This difference in motion drives currents and can lead to charge accumulation at the edges of regions of enhanced ionization. Polarization fields drive secondary currents which can reinforce the primary currents leading to electrojet formation. We estimate the magnitude of these electrojets and show that their magnetic perturbations can be detectable from both orbiting spacecraft and the surface. The magnitude of the electrojets can vary on diurnal and annual time scales as the strength and direction of the winds vary. These electrojets may lead to localized Joule heating, and closure of these currents may require field-aligned currents which may play a role in high altitude acceleration processes

Restoration of Hypoglycemia Awareness After Islet Transplantation

OBJECTIVE—To determine the impact of islet transplantation (ITx) on hypoglycemia awareness in patients with unstable type 1 diabetes and its relation to islet function

Quantum Locality

It is argued that while quantum mechanics contains nonlocal or entangled states, the instantaneous or nonlocal influences sometimes thought to be present due to violations of Bell inequalities in fact arise from mistaken attempts to apply classical concepts and introduce probabilities in a manner inconsistent with the Hilbert space structure of standard quantum mechanics. Instead, Einstein locality is a valid quantum principle: objective properties of individual quantum systems do not change when something is done to another noninteracting system. There is no reason to suspect any conflict between quantum theory and special relativity.Comment: Introduction has been revised, references added, minor corrections elsewhere. To appear in Foundations of Physic

Changes in the multidisciplinary management of rectal cancer from 2009 to 2015 and associated improvements in short‐term outcomes

Aim: Significant recent changes in management of locally advanced rectal cancer include preoperative staging, use of extended neoadjuvant therapies, and minimally invasive surgery (MIS). This study was aimed at characterizing those changes and associated short‐term outcomes. Method: We retrospectively analysed treatment and outcome data from patients with T3/4 or N+ locally advanced rectal cancer ≤15 cm from the anal verge who were evaluated at a comprehensive cancer center in 2009–2015. Results: In total, 798 patients were identified and grouped into five cohorts based on treatment year: 2009‐2010, 2011, 2012, 2013, and 2014‐2015. Temporal changes included increased reliance on MRI staging, from 57% in 2009‐2010 to 98% in 2014‐2015 (p < 0.001); increased use of total neoadjuvant therapy, from 17% to 76% (p < 0.001); and increased use of MIS, from 33% to 70% (p < 0.001). Concurrently, median hospital stay decreased (from 7 to 5 days; p < 0.001), as did the rates of grade III‐V complications (from 13% to 7%; p < 0.05), surgical site infections (from 24% to 8%; p < 0.001), anastomotic leak (from 11% to 3%; p < 0.05), and positive circumferential resection margin (from 9% to 4%; p < 0.05). TNM downstaging increased from 62% to 74% (p = 0.002). Conclusion: Shifts toward MRI‐based staging, total neoadjuvant therapy, and MIS occurred between 2009 and 2015. Over the same period, treatment responses improved, and lengths of stay and the incidence of complications decreased

Radio Emission from Ultra-Cool Dwarfs

The 2001 discovery of radio emission from ultra-cool dwarfs (UCDs), the very low-mass stars and brown dwarfs with spectral types of ~M7 and later, revealed that these objects can generate and dissipate powerful magnetic fields. Radio observations provide unparalleled insight into UCD magnetism: detections extend to brown dwarfs with temperatures <1000 K, where no other observational probes are effective. The data reveal that UCDs can generate strong (kG) fields, sometimes with a stable dipolar structure; that they can produce and retain nonthermal plasmas with electron acceleration extending to MeV energies; and that they can drive auroral current systems resulting in significant atmospheric energy deposition and powerful, coherent radio bursts. Still to be understood are the underlying dynamo processes, the precise means by which particles are accelerated around these objects, the observed diversity of magnetic phenomenologies, and how all of these factors change as the mass of the central object approaches that of Jupiter. The answers to these questions are doubly important because UCDs are both potential exoplanet hosts, as in the TRAPPIST-1 system, and analogues of extrasolar giant planets themselves.Comment: 19 pages; submitted chapter to the Handbook of Exoplanets, eds. Hans J. Deeg and Juan Antonio Belmonte (Springer-Verlag

A search for new MRI criteria for dissemination in space in subjects with a clinically isolated syndrome

The International Panel on the Diagnosis of Multiple Sclerosis (MS) incorporated the Barkhof/Tintoré (B/T) magnetic resonance criteria into their diagnostic scheme to provide evidence of dissemination in space of central nervous system lesions, a prerequisite for diagnosing MS in patients who present with clinically isolated syndromes (CIS). Although specific for MS, the B/T criteria were criticised for their low sensitivity and relative complexity in clinical use. We used lesion characteristics at onset from 349 CIS patients in logistic regression and recursive partitioning modelling in a search for simpler and more sensitive criteria, while maintaining current specificity. The resulting models, all based on the presence of periventricular and deep white matter lesions, performed roughly in agreement with the B/T criteria, but were unable to provide higher diagnostic accuracy based on information from a single scan. Apparently, findings from contrast-enhanced and follow-up magnetic resonance scans are needed to improve the diagnostic algorithm

The Saturn Ring Skimmer Mission Concept: The next step to explore Saturn's rings, atmosphere, interior, and inner magnetosphere

The innovative Saturn Ring Skimmer mission concept enables a wide range of investigations that address fundamental questions about Saturn and its rings, as well as giant planets and astrophysical disk systems in general. This mission would provide new insights into the dynamical processes that operate in astrophysical disk systems by observing individual particles in Saturn's rings for the first time. The Ring Skimmer would also constrain the origin, history, and fate of Saturn's rings by determining their compositional evolution and material transport rates. In addition, the Ring Skimmer would reveal how the rings, magnetosphere, and planet operate as an inter-connected system by making direct measurements of the ring's atmosphere, Saturn's inner magnetosphere and the material owing from the rings into the planet. At the same time, this mission would clarify the dynamical processes operating in the planet's visible atmosphere and deep interior by making extensive high-resolution observations of cloud features and repeated measurements of the planet's extremely dynamic gravitational field. Given the scientific potential of this basic mission concept, we advocate that it be studied in depth as a potential option for the New Frontiers program.Comment: White paper submitted to the Planetary Science and Astrobiology Decadal Survey (submission #420