All-electrical skyrmionic magnetic tunnel junction.

Topological whirls or 'textures' of spins such as magnetic skyrmions represent the smallest realizable emergent magnetic entities1-5. They hold considerable promise as robust, nanometre-scale, mobile bits for sustainable computing6-8. A longstanding roadblock to unleashing their potential is the absence of a device enabling deterministic electrical readout of individual spin textures9,10. Here we present the wafer-scale realization of a nanoscale chiral magnetic tunnel junction (MTJ) hosting a single, ambient skyrmion. Using a suite of electrical and multimodal imaging techniques, we show that the MTJ nucleates skyrmions of fixed polarity, whose large readout signal-20-70% relative to uniformly magnetized states-corresponds directly to skyrmion size. The MTJ exploits complementary nucleation mechanisms to stabilize distinctly sized skyrmions at zero field, thereby realizing three non-volatile electrical states. Crucially, it can electrically write and delete skyrmions to both uniform states with switching energies 1,000 times lower than the state of the art. Here, the applied voltage emulates a magnetic field and, in contrast to conventional MTJs, it reshapes both the energetics and kinetics of the switching transition, enabling deterministic bidirectional switching. Our stack platform enables large readout and efficient switching, and is compatible with lateral manipulation of skyrmionic bits, providing the much-anticipated backbone for all-electrical skyrmionic device architectures9,10. Its wafer-scale realizability provides a springboard to harness chiral spin textures for multibit memory and unconventional computing8,11.

Tuning of silicon nitride micro-cavities by controlled nanolayer deposition.

Integration of single-photon emitters (SPEs) with resonant photonic structures is a promising approach for realizing compact and efficient single-photon sources for quantum communications, computing, and sensing. Efficient interaction between the SPE and the photonic cavity requires that the cavity's resonance matches the SPE's emission line. Here we demonstrate a new method for tuning silicon nitride (Si3N4) microring cavities via controlled deposition of the cladding layers. Guided by numerical simulations, we deposit silicon dioxide (SiO2) nanolayers onto Si3N4 ridge structures in steps of 50 nm. We show tuning of the cavity resonance exceeding a free spectral range (FSR) of 3.5 nm without degradation of the quality-factor (Q-factor) of the cavity. We then complement this method with localized laser heating for fine-tuning of the cavity. Finally, we verify that the cladding deposition does not alter the position and spectral properties of nanoparticles placed on the cavity, which suggests that our method can be useful for integrating SPEs with photonic structures.

Foreign connections and the difference they make: how migrant ties influence political interest and attitudes in Mexico.

Beyond the economic and social effects of international migration researchers show regular exchanges between immigrants and stay-at-homes produce political spillovers in sending countries. As a broad body of literature demonstrates, most migrants maintain at least some form of contact with key connections back home, whether through long-distance communication, remittance sending, or in person visits. We investigate if exposure to international migration affects non-migrant citizens political interest, awareness, and attitudes about the efficacy of elections using longitudinal survey data from the Mexico 2006 Panel Study. We use a novel statistical approach combining Double Robust estimation technique with propensity score weighting. Our results suggest that Mexican non-migrant citizens exposed to international migration through social connections and remittances are more likely to be politically aware than those without. We also offer theoretical pathways to explain how ideational and material resources embedded in migrant social networks influences the political interest of stay-at-home citizens.

Lower than expected hepatitis B virus infection prevalence among first generation Koreans in the U.S.: results of HBV screening in the Southern California Inland Empire.

BACKGROUND: Hepatitis B virus (HBV) infection is prevalent in Asian immigrants in the USA. California's Inland Empire region has a population of approximately four million, including an estimated 19,000 first generation Koreans. Our aim was to screen these adult individuals to establish HBV serological diagnoses, educate, and establish linkage to care. METHODS: A community-based program was conducted in Korean churches from 11/2009 to 2/2010. Subjects were asked to complete a HBV background related questionnaire, provided with HBV education, and tested for serum HBsAg, HBsAb and HBcAb. HBsAg positive subjects were tested for HBV quantitative DNA, HBeAg and HBeAb, counseled and directed to healthcare providers. Subjects unexposed to HBV were invited to attend a HBV vaccination clinic. RESULTS: A total of 973 first generation Koreans were screened, aged 52.3y (18-93y), M/F: 384/589. Most (75%) had a higher than high school education and were from Seoul (62.2%). By questionnaire, 24.7% stated they had been vaccinated against HBV. The serological diagnoses were: HBV infected (3.0%), immune due to natural infection (35.7%), susceptible (20.1%), immune due to vaccination (40.3%), and other (0.9%). Men had a higher infection prevalence (4.9% vs. 1.7%, p = 0.004) and a lower vaccination rate (34.6% vs. 44.0%, p = 0.004) compared to women. Self-reports of immunization status were incorrect for 35.1% of subjects. CONCLUSIONS: This large screening study in first generation Koreans in Southern California demonstrates: 1) a lower than expected HBV prevalence (3%), 2) a continued need for vaccination, and 3) a need for screening despite a reported history of vaccination.

Use of ImPACT to diagnose minimal hepatic encephalopathy: an accurate, practical, user-friendly internet-based neuropsychological test battery.

BACKGROUND AND AIMS: An effective, user-friendly neurocognitive test to diagnose minimal hepatic encephalopathy (MHE) is needed. Immediate Post-concussion Assessment and Cognitive Testing (ImPACT) is a brief, validated, Web-based, neuropsychological test battery resulting in four composite scores [Verbal Memory (VrbM), Visual Memory, Visual Motor Speed (VMS), Reaction Time (RT)]. We compared ImPACT to traditional paper-and-pencil tests in patients at risk for MHE versus controls. METHODS: Ninety cirrhotic patients with no history of overt hepatic encephalopathy were compared with 131 controls on standard psychometric tests (SPT) [Trail Making Test-A, Trail Making Test-B, Digit Symbol Test], 4 ImPACT composite scores, and the Sickness Impact Profile (SIP). MHE+ was defined by a score 2 SD below the normative mean on at least one of the SPT. ImPACT (ImP+) scores of patients were defined as 2 SD from the control mean. RESULTS: Cirrhotic patients scored more poorly than controls on 3/4 of ImPACT scores: VrbM (78.88 vs. 71.37, p<0.001), VMS (26.47 vs. 22.68, p<0.001) and RT (0.89 vs. 1.00, p<0.01), as well as on all 3 SPT. Of the 90 cirrhotics, 16 (18%) were MHE+, who performed more poorly (p<0.001) than patients without MHE on VrbM (58.13 vs. 74.19), VMS (16.77 vs. 23.95) and RT (1.24 vs. 0.95). Of the 90 cirrhotics, 25 (27.8%) were ImP+. MHE+ and ImP+ patients had increased SIP scores versus controls (p<0.001). CONCLUSIONS: Compared to paper-and-pencil testing, ImPACT provides a brief, user-friendly, neuropsychological evaluation of MHE. ImPACT could become a new standard for MHE diagnosis.

Estimating conditional proportion curves by regression residuals.

Researchers often derive a categorical outcome from an observed continuous measurement y. For example, human obesity status can be defined by the body mass index. They proceed to estimate the conditional proportion curve p(x) = P(y

Factors influencing the enrollment of eligible extremely-low-birth-weight children in the part C early intervention program.

OBJECTIVE: To determine whether eligible extremely-low-birth-weight children (<1000 g) were enrolled in the federally enacted, state-coordinated Early Intervention (EI) program intended to help children with developmental delay or disability regardless of parental income, and the factors associated with enrollment. METHODS: Retrospective analysis of 884 EI-eligible ELBW children born in South Carolina with birth weight 401 to 999 g, gestation > or =24 weeks, and survival for the first 120 days of life. We created a linked data set with data from Early Intervention (1996-2001), Vital Records (1996-1998), death certificates, and Medicaid. Each child was followed from birth to 3 years old, the program eligibility period. RESULTS: A total of 54% of ELBW children were enrolled in EI at any time from birth to 36 months. Even among children ever enrolled in Medicaid (83% of all ELBW children), only 63% were enrolled in EI. Being born in a multiple gestational birth, having heavier birth weight (750 to 999 g), and having ever enrolled in Medicaid were positively associated with EI enrollment. Among Medicaid patients for whom perinatal data were available, additional risk adjustment showed that EI enrollment was more likely with birth in level 3 hospitals, birth weight 750 to 999 g, Neonatal Medical Index severity level V (most severe), and longer initial length of hospital stay. CONCLUSIONS: Only about half of eligible ELBW children in South Carolina were enrolled-much lower than reported elsewhere. Efforts are needed to understand why eligible infants are not being enrolled and to develop strategies to remedy the situation.

Clinical significance of elevated alpha-fetoprotein (AFP) in patients with chronic hepatitis C, but not hepatocellular carcinoma.

BACKGROUND: Although elevated serum alpha-fetoprotein (AFP) is often seen in patients with chronic hepatitis C (CHC), its prevalence, risk factors, and clinical significance remain to be determined. AIMS: The present study assessed the frequency of, the risk factors for, and the clinical significance of elevated AFP in patients with CHC, but not hepatocellular carcinoma. METHODS: This retrospective study utilized systematic chart review and statistical analyses to investigate 357 U.S. patients with CHC from a university medical center and a regional veteran administration medical center. RESULTS: The prevalence of elevated serum AFP (i.e., >/=10.0 microg/L) was 23.0%, including 15.3% (28/183), 24.5% (25/102), and 42.0% (29/69) in patients with chronic hepatitis C and stage 0-II, III, and IV hepatic fibrosis, respectively. After adjusting for age, HCV load, and hepatic steatosis, stage III/IV fibrosis, elevated aspartate aminotransferase (AST), and prolonged prothrombin time as measured by international normalized ratio (INR) remained independently associated with elevated serum AFP in these patients. A serum AFP level of 15.0 microg/L was 22.8% sensitive and 94.5% specific for stage III/IV fibrosis. CONCLUSIONS: In patients with chronic hepatitis C, 23.0% had elevated serum AFP that is independently associated with stage III/IV hepatic fibrosis, elevated level of AST, and prolonged INR.

Phase I trial of gemcitabine and paclitaxel in advanced solid tumors.

PURPOSE: Gemcitabine and paclitaxel are chemotherapeutic agents with clinical antitumor activity in a broad range of malignant solid tumors. Because of preclinical synergy, unique mechanisms of action and resistance, and nonoverlapping toxicities, gemcitabine and paclitaxel combinations are attractive for testing in clinical trials. Prior weekly gemcitabine and paclitaxel regimens administered on a 28-day cycle have been limited by cumulative hematological toxicity on day 15, thus reducing the planned gemcitabine dose intensity. We therefore conducted a phase I trial of a 21-day schedule of weekly gemcitabine and paclitaxel to determine the tolerability, maximum tolerated dose (MTD), and preliminary estimates of efficacy of this regimen. PATIENTS AND METHODS: Forty-one patients with advanced malignant solid tumors were accrued. Gemcitabine was given at a fixed dose of 1000 mg/m2 while paclitaxel was administered at an initial dose of 60 mg/m2, then escalated by 15 mg/m2 increments over seven dose levels to a prospectively planned maximum dose of 150 mg/m2. Both agents were infused intravenously on days one and eight every 21 days. At least three patients were enrolled per dose level. No intrapatient dose escalation was allowed. RESULTS: All patients were assessable for toxicity and 31 were assessable for response. The regimen was generally well-tolerated. Dose-limiting thrombocytopenia was observed in one patient at a paclitaxel dose of 135 mg/m2/week (dose level 6). After expansion of this dose level by 14 additional patients, no further dose-limiting toxicities were observed although one patient at dose level seven died of neutropenic sepsis after completing three cycles. There were eight partial responders for an overall response proportion of 26% (95% CI: 11, 41). Twelve patients (39%) had stable disease. CONCLUSION: This 21-day schedule of gemcitabine and paclitaxel is safe, well-tolerated, and active. The recommended phase II dose is gemcitabine 1000 mg/m2 and paclitaxel 150 mg/m2 on days one and eight every 21 days. The antitumor activity observed with this regimen warrants further investigation.