Observation of the Helium 7 Lambda hypernucleus by the (e,e'K+) reaction

An experiment with a newly developed high-resolution kaon spectrometer (HKS) and a scattered electron spectrometer with a novel configuration was performed in Hall C at Jefferson Lab (JLab). The ground state of a neutron-rich hypernucleus, He 7 Lambda, was observed for the first time with the (e,e'K+) reaction with an energy resolution of ~0.6 MeV. This resolution is the best reported to date for hypernuclear reaction spectroscopy. The he 7 Lambda binding energy supplies the last missing information of the A=7, T=1 hypernuclear iso-triplet, providing a new input for the charge symmetry breaking (CSB) effect of \Lambda N potential.Comment: 5 pages, 4 figures, submitted to PR

Multimodel assessment of the factors driving stratospheric ozone evolution over the 21st century

The evolution of stratospheric ozone from 1960 to 2100 is examined in simulations from 14 chemistry‐climate models, driven by prescribed levels of halogens and greenhouse gases. There is general agreement among the models that total column ozone reached a minimum around year 2000 at all latitudes, projected to be followed by an increase over the first half of the 21st century. In the second half of the 21st century, ozone is projected to continue increasing, level off, or even decrease depending on the latitude. Separation into partial columns above and below 20 hPa reveals that these latitudinal differences are almost completely caused by differences in the model projections of ozone in the lower stratosphere. At all latitudes, upper stratospheric ozone increases throughout the 21st century and is projected to return to 1960 levels well before the end of the century, although there is a spread among models in the dates that ozone returns to specific historical values. We find decreasing halogens and declining upper atmospheric temperatures, driven by increasing greenhouse gases, contribute almost equally to increases in upper stratospheric ozone. In the tropical lower stratosphere, an increase in upwelling causes a steady decrease in ozone through the 21st century, and total column ozone does not return to 1960 levels in most of the models. In contrast, lower stratospheric and total column ozone in middle and high latitudes increases during the 21st century, returning to 1960 levels well before the end of the century in most models

Sensory prediction errors in the continuum of psychosis

Sensory prediction errors are fundamental brain responses that signal a violation of expectation in either the internal or external sensory environment, and are therefore crucial for survival and adaptive behaviour. Patients with schizophrenia show deficits in these internal and external sensory prediction errors, which can be measured using electroencephalography (EEG) components such as N1 and mismatch negativity (MMN), respectively. New evidence suggests that these deficits in sensory prediction errors are more widely distributed on a continuum of psychosis, whereas psychotic experiences exist to varying degrees throughout the general population. In this paper, we review recent findings in sensory prediction errors in the auditory domain across the continuum of psychosis, and discuss these in light of the predictive coding hypothesis

Auditory white matter pathways are associated with effective connectivity of auditory prediction errors within a fronto-temporal network

Auditory prediction errors, i.e. the mismatch between predicted, forthcoming auditory sensations and actual sensory input, trigger the detection of surprising auditory events in the environment. Auditory mismatches engage a hierarchical functional network of cortical sources, which are also interconnected by auditory white matter pathways. Hence it is plausible that these structural and functional networks are quantitatively related. The present study set out to investigate whether structural connectivity of auditory white matter pathways enables the effective connectivity underpinning auditory mismatch responses. Participants (N = 89) underwent diffusion weighted magnetic resonance imaging (MRI) and electroencephalographic (EEG) recordings. Anatomically-constrained tractography was used to extract auditory white matter pathways, namely the bilateral arcuate fasciculi, inferior fronto-occipital fasciculi (IFOF), and the auditory interhemispheric pathway, from which Apparent Fibre Density (AFD) was calculated. EEG data were recorded in the same participants during a stochastic oddball paradigm, which was used to elicit auditory prediction error responses. Dynamic causal modelling was used to investigate the effective connectivity underlying auditory mismatch responses generated in brain regions interconnected by the above mentioned auditory white matter pathways. Our results showed that brain areas interconnected by all auditory white matter pathways best explained the dynamics of auditory mismatch responses. Furthermore, AFD in the right arcuate fasciculus was significantly associated with the effective connectivity between the cortical regions that lie within it. Taken together, these findings indicate that auditory prediction errors recruit a fronto-temporal network of brain regions that are effectively and structurally connected by auditory white matter pathways

White matter connectivity reductions in the pre-clinical continuum of psychosis: a connectome study

Widespread white matter connectivity disruptions have commonly been reported in schizophrenia. However, it is questionable whether structural connectivity decline is specifically associated with schizophrenia or whether it extends along a continuum of psychosis into the healthy population. Elucidating brain structure changes associated with psychotic-like experiences in healthy individuals is insofar important as it is a necessary first step towards our understanding of brain pathology preceding florid psychosis. High resolution, multishell diffusion-weighted magnetic resonance images (MRI) were acquired from 89 healthy individuals. Whole-brain white matter fibre tracking was performed to quantify the strength of white matter connections. Network-based statistics were applied to white matter connections in a regression model in order to test for a linear relationship between streamline count and psychotic-like experiences. A significant subnetwork was identified whereby streamline count declined with increasing psychotic-like experiences. This network of structural connectivity reductions affected all cortical lobes, subcortical structures and the cerebellum and spanned along prominent association and commissural white matter pathways. A widespread network of linearly declining connectivity strength with increasing number of psychotic-like experiences was identified in healthy individuals. This finding is in line with white matter connectivity reductions reported from early to chronic stages of schizophrenia and might therefore aid the development of tools to identify individuals at risk of transitioning to psychosis

Human antibody responses to the Plasmodium vivax Duffy Binding protein in Sri Lanka

Recombinant protein DBP, expressed in a bacculoviral vector, representing the native Plasmodium vivax Duffy Binding Protein (DBP) was used in an indirect ELISA to assay the total anti-DBP antibody (IgM + IgG) responses in Sri Lankan patients with acute vivax malaria. The test populations were selected from two malaria endemic areas, Anuradhapura (n=64) and Kataragama (n=93), and from an area non-endemic for malaria, Colombo (n=91). The prevalences of anti-DBP antibodies were 53%, 38% and 44% from Anuradhapura, Kataragama and Colombo, respectively. A significant difference (Chi-square test, p<0.05) was found between the proportions of responders and non-responders to DBP in Kataragama. Responding proportions of individuals previously exposed (PE) and previously not exposed (PNE) differed significantly only in Colombo (Chi-square test, p<0.05). Significant differences (Mann-Whitney U test, p<0.05) were evident between anti-DBP antibody magnitudes; (i) in Anuradhapura and Kataragama and (ii) of PNE individuals from Colombo and the total responders (both PNE + PE) from Anuradhapura. A significant difference (Mann-Whitney U test, p<0.01) in the end point titers (EPT) between PNE and PE individuals was limited to Colombo. Associations between host factors (age, parasitaemia, number of past infections, the duration between present and penultimate infections and the days of symptoms) and total antibody responses (antibody magnitudes and EPT) were examined (Spearman Correlation coefficient, p<0.05). The significant associations found were between (i) parasitaemia and then total antibody responses of residents in Anuradhapura, (ii) between the parasitaemia group <0.01% and the total antibody response of residents in Kataragama (a negative correlation), (iii) number of past infections in Colombo and (iv) the duration between the present and penultimate infections in Colombo and in Anuradhapura with EPT and the antibody magnitudes, respectively. In conclusion, results of the present study imply that naturally acquired anti-DBP antibodies may play a functional role in the immunity to vivax malaria in Sri Lanka. Acknowledgement: Financial assistance by the University of Colombo and the International foundation for Science, Sweden (Grant No: F3008-1

Comparison of the two different recombinant proteins representing region II of the Duffy binding protein of Plasmodium vivax by assaying for natural antibodies

Two different recombinant proteins representing region II of the Duffy Binding Protein of Plasmodium vivax, DBP and PvRII expressed in the bacculovirus and Eschericia coli vector systems, respectively, were compared by assaying the total immunoglobulin (IgM + IgG) responses of sera of patients with acute vivax malaria in an indirect ELISA. The patients were from two malaria endemic areas, Anuradhapura (n=64) and Kataragama (n=90), and a nonendemic area, Colombo (n=90). The antibody prevalence was 50% and 44% from Anuradhapura, 39% and 28% Kataragama and 57% and 41% from Colombo, for PvRII and DBP, respectively. The antibody prevalence for PvRII was higher than that for DBP in each test area, that was significant only in Colombo (p=0.001). The percentages of patients that they responded to both proteins were 34% (n=22), 19% (n=17) and 40% (n=36) from Anuradhapura, Kataragama and from Colombo, respectively. In comparison, a significantly lower (p=0.007) percentage of individuals from Kataragama responded to both proteins. Further 16% (n=10) from Anuradhapura, 19% (n=17) from Kataragama and 16% (n=14) from Colombo preferentially recognised PvRII, whereas, corresponding values for DBP were 9% (n=6), 10% (n=9) and 1% (n=1), respectively, where this difference was significant only in Colombo (p=0.031). Among the previously non-exposed patients from Colombo, 24% responded preferentially to PvRII whereas it was only 3% for DBP (p=0.021).On the other hand, of the previously exposed patients from Colombo, 10% preferentially responded to PvRII whereas no preferential recognition of DBP was observed (p=0.063). Thus the results of this study show a higher natural antibody response to recombinant protein PvRII, which represents the functional conformation of region II of the Duffy Binding Protein. We are thankful to Dr Chitnis, Malaria Division, ICGEB, New Delhi, India and Dr S Longacre, Department of Immunology, Institute Pasteur, France for kindly providing the two recombinant proteins. Financial support by the International Foundation for Science, Sweden (Grant No: F3008-1) and University of Colombo (Grant No: 2001/S/23) are acknowledged

Natural Human Antibody Responses to Plasmodium vivax Apical Membrane Antigen 1 under Low Transmission and Unstable Malaria Conditions in Sri Lanka

Plasmodium vivax apical membrane antigen 1, an important malaria vaccine candidate, was immunogenic during natural malaria infections in Sri Lanka, where low transmission and unstable malaria conditions prevail. Antibody prevalence increased with exposure in areas where malaria was or was not endemic. A marked isotype switch to cytophilic (immunoglobulin G1 [IgG1]/IgG3) antibodies was evident with increasing exposure exclusively in residents from areas of endemicity