Field induced transitions in a kagome antiferromagnet

The thermal order by disorder effect in magnetic field is studied for a classical Heisenberg antiferromagnet on the kagome lattice. Using analytical arguments we predict a unique H-T phase diagram for this strongly frustrated magnet: states with a coplanar and a uniaxial triatic order parameters respectively at low and high magnetic fields and an incompressible collinear spin-liquid state at a one-third of the saturation field. We also present the Monte Carlo data which confirm existence of these phases.Comment: 4 pages, 2 figures, accepted versio

Ultraearly thrombolysis by an anesthesiologist in a mobile stroke unit: A prospective, controlled intervention study

Background Acute stroke treatment in mobile stroke units (MSU) is feasible and reduces time-to-treatment, but the optimal staffing model is unknown. We wanted to explore if integrating thrombolysis of acute ischemic stroke (AIS) in an anesthesiologist-based emergency medical services (EMS) reduces time-to-treatment and is safe. Methods A nonrandomized, prospective, controlled intervention study. Inclusion criteria: age ≥18 years, nonpregnant, stroke symptoms with onset ≤4 h. The MSU staffing is inspired by the Norwegian Helicopter Emergency Medical Services crew with an anesthesiologist, a paramedic-nurse and a paramedic. Controls were included by conventional ambulances in the same catchment area. Primary outcome was onset-to-treatment time. Secondary outcomes were alarm-to-treatment time, thrombolytic rate and functional outcome. Safety outcomes were symptomatic intracranial hemorrhage and mortality. Results We included 440 patients. MSU median (IQR) onset-to-treatment time was 101 (71–155) minutes versus 118 (90–176) minutes in controls, p = 0.007. MSU median (IQR) alarm-to-treatment time was 53 (44–65) minutes versus 74 (63–95) minutes in controls, p < 0.001. Golden hour treatment was achieved in 15.2% of the MSU patients versus 3.7% in the controls, p = 0.005. The thrombolytic rate was higher in the MSU (81% vs 59%, p = 0.001). MSU patients were more often discharged home (adjusted OR [95% CI]: 2.36 [1.11–5.03]). There were no other significant differences in outcomes. Conclusions Integrating thrombolysis of AIS in the anesthesiologist-based EMS reduces time-to-treatment without negatively affecting outcomes. An MSU based on the EMS enables prehospital assessment of acute stroke in addition to other medical and traumatic emergencies and may facilitate future implementation.publishedVersio

The quiet crossing of ocean tipping points

Anthropogenic climate change profoundly alters the ocean’s environmental conditions, which, in turn, impact marine ecosystems. Some of these changes are happening fast and may be difficult to reverse. The identification and monitoring of such changes, which also includes tipping points, is an ongoing and emerging research effort. Prevention of negative impacts requires mitigation efforts based on feasible research-based pathways. Climate-induced tipping points are traditionally associated with singular catastrophic events (relative to natural variations) of dramatic negative impact. High-probability high-impact ocean tipping points due to warming, ocean acidification, and deoxygenation may be more fragmented both regionally and in time but add up to global dimensions. These tipping points in combination with gradual changes need to be addressed as seriously as singular catastrophic events in order to prevent the cumulative and often compounding negative societal and Earth system impacts

Enhanced magnetocaloric effect in frustrated magnets

The magnetothermodynamics of strongly frustrated classical Heisenberg antiferromagnets on kagome, garnet, and pyrochlore lattices is examined. The field induced adiabatic temperature change (dT/dH)_S is significantly larger for such systems compared to ordinary non-frustrated magnets and also exceeds the cooling rate of an ideal paramagnet in a wide range of fields. An enhancement of the magnetocaloric effect is related to presence of a macroscopic number of soft modes in frustrated magnets below the saturation field. Theoretical predictions are confirmed with extensive Monte Carlo simulations.Comment: 7 page

Very early mobilization of patients with stroke: a systematic review

Rapporten kan lastes ned gratis fra Folkehelseinstituttets nettsider : www.fhi.noI 2014 ble 9600 personer lagt inn i sykehus med akutt hjerneslag i Norge. Dødeligheten som følge av hjerneslag er betydelig redusert de siste ti-årene, men mange pasienter med hjerneslag får varige nevrologiske funksjonsnedsettelser. Et viktig element i behandlingen av pasienter med akutt hjerneslag er at pasienten mobiliseres tidlig, men det er uklart om det er mest effektivt om dette skjer innen 24 timer eller mellom 24 - 48 timer etter symptomdebut. Vårt mandat var å identifisere og oppsummere studier som hadde belyst dette.publishedVersio

Stretching after treatment with botulinum toxin for adult patients with spasticity; A sys‐ tematic mapping review

Rapporten lastes ned gratis fra: Folkehelseinstituttets nettsider www.fhi.noNasjonalt kunnskapssenter for helsetjenesten i Folkehelseinstituttet fikk en forespørsel fra Irene Krystad ved fysioterapitjenesten i Tysvær kommune om å finne forskning om effekt av tøyning etter behandling med botulinumtoksin av voksne pasienter med spastisitet. De hadde funnet begrenset dokumentasjon etter egne søk etter litteratur, og så behovet for å finne fram til denne på en systematisk måte. Vi utførte en kartleggingsoversikt der vi søkte etter systematiske oversikter og randomiserte kontrollerte studier på effekten av tøyning etter behandling med botulinumtoksin versus behandling med botulinumtoksin alene på voksne pasienter med spastisitet. Søket etter systematiske oversikter resulterte i 1109 referanser. Av disse inkluderte vi fire systematiske oversikter. Disse inkluderte til sammen fem randomiserte studier med totalt 119 pasienter på den aktuelle problemstillingen. Den ene primærstudien som var inkludert i oversiktene vurderte vi til at ikke å omfatte tøyning og vi inkluderte derfor ikke denne studien blant de randomiserte kontrollerte studiene. Søket etter randomiserte kontrollerte studier resulterte i 2617 referanser, hvorav vi inkluderte fem randomiserte kontrollerte studier med totalt 138 pasienter. Fire av disse primærstudiene var allerede inkludert i de systematiske oversiktene. Vi avdekket kunnskapshull når det gjelder primærforskning på effekten av tøyning etter behandling med botulinumtoksin versus botulinumtoksin alene.publishedVersio

Serological markers of extracellular matrix remodeling predict transplant‐free survival in primary sclerosing cholangitis

BACKGROUND: Primary sclerosing cholangitis is a progressive liver disease with a remarkably variable course. Biomarkers of disease activity or prognostic models predicting outcome at an individual level are currently not established. AIM: To evaluate the prognostic utility of four biomarkers of basement membrane and interstitial extracellular matrix remodeling in patients with primary sclerosing cholangitis. METHODS: Serum samples were available from 138 large‐duct primary sclerosing cholangitis patients (of which 102 [74%] with IBD) recruited 2008‐2012 and 52 ulcerative colitis patients (controls). The median follow‐up time was 2.2 (range 0‐4.3) years. Specific biomarkers of type III and V collagen formation (PRO‐C3 and PRO‐C5, respectively) and type III and IV collagen degradation (C3M and C4M, respectively) were assessed. The Enhanced Liver Fibrosis test, including procollagen type III N‐terminal peptide, tissue inhibitor of metalloproteinase‐1 and hyaluronic acid was assessed for comparison. RESULTS: All markers were elevated in primary sclerosing cholangitis compared to ulcerative colitis patients (P < 0.001). PRO‐C3 showed the largest difference between the two groups with a threefold increase in primary sclerosing cholangitis compared to ulcerative colitis patients. Patients with high baseline serum levels of all markers, except C3M, had shorter survival compared to patients with low baseline serum levels (P < 0.001). Combining PRO‐C3 and PRO‐C5 the odds ratio for predicting transplant‐free survival was 47 compared to the Enhanced Liver Fibrosis test's odds ratio of 11. CONCLUSIONS: Extracellular matrix remodeling is elevated in primary sclerosing cholangitis patients compared to ulcerative colitis patients. Furthermore, the interstitial matrix marker PRO‐C3 was identified as a potent prognostic marker and an independent predictor of transplant‐free survival in primary sclerosing cholangitis

Field induced ordering in highly frustrated antiferromagnets

We predict that an external field can induce a spin order in highly frustrated classical Heisenberg magnets. We find analytically stabilization of collinear states by thermal fluctuations at a one-third of the saturation field for kagome and garnet lattices and at a half of the saturation field for pyrochlore and frustrated square lattices. This effect is studied numerically for the frustrated square-lattice antiferromagnet by Monte Carlo simulations for classical spins and by exact diagonalization for $S=1/2$. The field induced collinear states have a spin gap and produce magnetization plateaus.Comment: 4 pages, new analytical proof the order by disorder by thermal fluctuations is adde

Electrostatic Modifications of the Human Leukocyte Antigen-DR P9 Peptide-Binding Pocket and Susceptibility to Primary Sclerosing Cholangitis

The strongest genetic risk factors for primary sclerosing cholangitis (PSC) are found in the human leukocyte antigen (HLA) complex at chromosome 6p21. Genes in the HLA class II region encode molecules that present antigen to T lymphocytes. Polymorphisms in these genes are associated with most autoimmune diseases, most likely because they contribute to the specificity of immune responses. The aim of this study was to analyze the structure and electrostatic properties of the peptide-binding groove of HLA-DR in relation to PSC. Thus, four-digit resolution HLA-DRB1 genotyping was performed in 356 PSC patients and 366 healthy controls. Sequence information was used to assign which amino acids were encoded at all polymorphic positions. In stepwise logistic regressions, variations at residues 37 and 86 were independently associated with PSC (P = 1.2 × 10−32 and P = 1.8 × 10−22 in single-residue models, respectively). Three-dimensional modeling was performed to explore the effect of these key residues on the HLA-DR molecule. This analysis indicated that residue 37 was a major determinant of the electrostatic properties of pocket P9 of the peptide-binding groove. Asparagine at residue 37, which was associated with PSC, induced a positive charge in pocket P9. Tyrosine, which protected against PSC, induced a negative charge in this pocket. Consistent with the statistical observations, variation at residue 86 also indirectly influenced the electrostatic properties of this pocket. DRB1*13:01, which was PSC-associated, had a positive P9 pocket and DRB1*13:02, protective against PSC, had a negative P9 pocket. Conclusion: The results suggest that in patients with PSC, residues 37 and 86 of the HLA-DRβ chain critically influence the electrostatic properties of pocket P9 and thereby the range of peptides presented. (Hepatology 2011;53:1967-1976

Transition to Long Range Magnetic Order in the Highly Frustrated Insulating Pyrochlore Antiferromagnet Gd_2Ti_2O_7

Experimental evidence from measurements of the a.c. and d.c. susceptibility, and heat capacity data show that the pyrochlore structure oxide, Gd_2Ti_2O_7, exhibits short range order that starts developing at 30K, as well as long range magnetic order at $T\sim 1$K. The Curie-Weiss temperature, $\theta_{CW}$ = -9.6K, is largely due to exchange interactions. Deviations from the Curie-Weiss law occur below $\sim$10K while magnetic heat capacity contributions are found at temperatures above 20K. A sharp maximum in the heat capacity at $T_c=0.97$K signals a transition to a long range ordered state, with the magnetic specific accounting for only $\sim$ 50% of the magnetic entropy. The heat capacity above the phase transition can be modeled by assuming that a distribution of random fields acts on the $^8S_{7/2}$ ground state for Gd$^{3+}$. There is no frequency dependence to the a.c. susceptibility in either the short range or long range ordered regimes, hence suggesting the absence of any spin-glassy behavior. Mean field theoretical calculations show that no long range ordered ground state exists for the conditions of nearest-neighbor antiferromagnetic exchange and long range dipolar couplings. At the mean-field level, long range order at various commensurate or incommensurate wave vectors is found only upon inclusion of exchange interactions beyond nearest-neighbor exchange and dipolar coupling. The properties of Gd$_2Ti_2O_7 are compared with other geometrically frustrated antiferromagnets such as the Gd_3Ga_5O_{12} gadolinium gallium garnet, RE_2Ti_2O_7 pyrochlores where RE = Tb, Ho and Tm, and Heisenberg-type pyrochlore such as Y_2Mo_2O_7, Tb_2Mo_2O_7, and spinels such as ZnFe_2O_4Comment: Letter, 6 POSTSCRIPT figures included. (NOTE: Figure 5 is not included --) To appear in Physical Review B. Contact: [email protected]