Magnetic versus crystal field linear dichroism in NiO thin films

We have detected strong dichroism in the Ni $L_{2,3}$ x-ray absorption spectra of monolayer NiO films. The dichroic signal appears to be very similar to the magnetic linear dichroism observed for thicker antiferromagnetic NiO films. A detailed experimental and theoretical analysis reveals, however, that the dichroism is caused by crystal field effects in the monolayer films, which is a non trivial effect because the high spin Ni $3d^{8}$ ground state is not split by low symmetry crystal fields. We present a practical experimental method for identifying the independent magnetic and crystal field contributions to the linear dichroic signal in spectra of NiO films with arbitrary thicknesses and lattice strains. Our findings are also directly relevant for high spin $3d^{5}$ and $3d^{3}$ systems such as LaFeO$_{3}$, Fe$_{2}$O$_{3}$, VO, LaCrO$_{3}$, Cr$_{2}$O$_{3}$, and Mn$^{4+}$ manganate thin films

Potential contribution of ancient introgression to the evolution of a derived reproductive strategy in ricefishes

Transitions from no parental care to extensive care are costly and involve major changes in life history, behaviour and morphology. Nevertheless, in Sulawesi ricefishes, pelvic brooding evolved from transfer brooding in two distantly related lineages within the genera Adrianichthys and Oryzias, respectively. Females of pelvic brooding species carry their eggs attached to their belly until the fry hatches. Despite their phylogenetic distance, both pelvic brooding lineages share a set of external morphological traits. A recent study found no direct gene flow between pelvic brooding lineages, suggesting independent evolution of the derived reproductive strategy. Convergent evolution can, however, also rely on repeated sorting of pre-existing variation of an admixed ancestral population, especially when subjected to similar external selection pressures. We thus used a multi-species coalescent (MSC) model and D-statistics to identify gene-tree - species-tree incongruencies, to evaluate the evolution of pelvic brooding with respect to inter-specific gene flow not only between pelvic brooding lineages, but between pelvic brooding lineages and other Sulawesi ricefish lineages. We found a general network-like evolution in Sulawesi ricefishes and as previously reported, no gene flow between the pelvic brooding lineages. Instead, we found hybridization between the ancestor of pelvic brooding Oryzias and the common ancestor of the Oryzias species from the Lake Poso area. We further detected signs of introgression within the confidence interval of a quantitative trait locus (QTL) associated with pelvic brooding in O. eversi. Our results hint towards a contribution of ancient standing genetic variation to the evolution of pelvic brooding in Oryzias

The contribution of staff call light response time to fall and injurious fall rates: an exploratory study in four US hospitals using archived hospital data

Abstract Background Fall prevention programs for hospitalized patients have had limited success, and the effect of programs on decreasing total falls and fall-related injuries is still inconclusive. This exploratory multi-hospital study examined the unique contribution of call light response time to predicting total fall rates and injurious fall rates in inpatient acute care settings. The conceptual model was based on Donabedian's framework of structure, process, and health-care outcomes. The covariates included the hospital, unit type, total nursing hours per patient-day (HPPDs), percentage of the total nursing HPPDs supplied by registered nurses, percentage of patients aged 65 years or older, average case mix index, percentage of patients with altered mental status, percentage of patients with hearing problems, and call light use rate per patient-day. Methods We analyzed data from 28 units from 4 Michigan hospitals, using archived data and chart reviews from January 2004 to May 2009. The patient care unit-month, defined as data aggregated by month for each patient care unit, was the unit of analysis (N = 1063). Hierarchical multiple regression analyses were used. Results Faster call light response time was associated with lower total fall and injurious fall rates. Units with a higher call light use rate had lower total fall and injurious fall rates. A higher percentage of productive nursing hours provided by registered nurses was associated with lower total fall and injurious fall rates. A higher percentage of patients with altered mental status was associated with a higher total fall rate but not a higher injurious fall rate. Units with a higher percentage of patients aged 65 years or older had lower injurious fall rates. Conclusions Faster call light response time appeared to contribute to lower total fall and injurious fall rates, after controlling for the covariates. For practical relevance, hospital and nursing executives should consider strategizing fall and injurious fall prevention efforts by aiming for a decrease in staff response time to call lights. Monitoring call light response time on a regular basis is recommended and could be incorporated into evidence-based practice guidelines for fall prevention.http://deepblue.lib.umich.edu/bitstream/2027.42/112579/1/12913_2011_Article_2004.pd

Strong spin-dependent electron correlation effects in photoemission from itinerant magnets

The Fe 2p photoemission of ferromagnetic iron shows a dichroism which indicates a strong difference in hybridization for spin-up and spin-down electrons. In contrast, the dichroism of the localized Mn surface alloys reveals intense unscreened satellite structure. The spin polarization of the core hole is quantified using the dichroism in the Fe $L_3M_{2,3}M_{2,3}$ Auger spectrum measured with the light helicity vector perpendicular to the magnetization direction. The observations in the 3d metals are in strong contradiction with the expectations from an independent-particle model

Transverse magneto-optical Kerr effect of Fe at the Fe 3p threshold

We have studied the transverse magneto-optical Kerr effect of a Fe[(5.7% Si)001] sample and of ultrathin films of Fe evaporated onto Ag(001) in the soft-x-ray regime at the 3p core level threshold of Fe. We test the relationship between the asymmetries in the reflectivity and in the total photoyield which have been measured simultaneously

Potentiation of cerebellar Purkinje cells facilitates whisker reflex adaptation through increased simple spike activity

Cerebellar plasticity underlies motor learning. However, how the cerebellum operates to enable learned changes in motor output is largely unknown. We developed a sensory-driven adaptation protocol for reflexive whisker protraction and recorded Purkinje cell activity from crus 1 and 2 of awake mice. Before training, simple spikes of individual Purkinje cells correlated during reflexive protraction with the whisker position without lead or lag. After training, simple spikes and whisker protractions were both enhanced with the spiking activity now leading behavioral responses. Neuronal and behavioral changes did not occur in two cell-specific mouse models with impaired long-term potentiation at their parallel fiber to Purkinje cell synapses. Consistent with cerebellar plasticity rules, increased simple spike activity was prominent in cells with low complex spike response probability. Thus, potentiation at parallel fiber to Purkinje cell synapses may contribute to reflex adaptation and enable expression of cerebellar learning through increases in simple spike activity