Dynamics of genuine multipartite correlations in open quantum systems

We propose a measure for genuine multipartite correlations suited for the study of dynamics in open quantum systems. This measure is contextual in the sense that it depends on how information is read from the environment. It is used to study an interacting collective system of atoms undergoing phase transitions as external parameters are varied. We show that the steady state of the system can have a significant degree of genuine multipartite quantum and classical correlations, and that the proposed measure can serve as a witness of critical behavior in quantum systems.Comment: 5 pages, 3 figure

Middle-Upper Ordovician and Silurian stratigraphy and basin development in southernmost Scandinavia

A complete log-stratigraphical breakdown of the Middle Ordovician to lower Silurian shale-dominated succession is presented for the Bornholm–Skåne–Kattegat area in southernmost Scandinavia. A wireline log zonation developed for the onshore Bornholm Palaeozoic shales is extended to include the offshore Palaeozoic shales in the adjacent Rønne Graben. A complete log zonation scheme for the Cyrtograptus shale (late Llandovery–Wenlock) and the lower part of the Colonus shale (Ludlow) is presented including correlation within the Bornholm–Skåne–Kattegat area. The Cyrtograptus shale in the Bornholm area is estimated to be 400 m thick and marks the shift to a rapidly subsiding foreland basin, heralding the Caledonian Orogeny

The Lower Palaeozoic now fully cored and logged on Bornholm, Denmark

A 558 m long, complete section of the Lower Palaeozoic succession preserved onshore southern Bornholm has been compiled from five fully cored scientific wells, carried out between 2005 and 2012. The scientific programme included coring and geophysical logging of the five scientific wells that yielded a total of c. 750 m of partially overlapping cores as well as re-logging of water wells and acquisition of shallow seismic data. The last well drilled, the Sommerodde-1, cored the youngest preserved Silurian strata on Bornholm including strata not exposed in outcrops. The well penetrated 168.1 m of Silurian shales, 42.7 m of Upper Ordovician shales and 27.9 m of Alum Shale before it terminated at a depth of 250.3 m in the Lower Cambrian Norretorp Member of the Læså Formation. Th e Sommerodde-1 well documents that the Lower Silurian Cyrtograptus shale is at least 91.7 m thick and that the Rastrites shale is 76.4 m thick. The complete Lower Cambrian succession has previously been covered by the 316.0 m deep Borggård-1 well that terminated in basement rocks (Nielsen et al. 2006)

Early Silurian δ¹³Corg excursions in the foreland basin of Baltica, both familiar and surprising

The Sommerodde-1 core from Bornholm, Denmark, provides a nearly continuous sedimentary archive from the Upper Ordovician through to the Wenlock Series (lower Silurian), as constrained by graptolite biostratigraphy. The cored mudstones represent a deep marine depositional setting in the foreland basin fringing Baltica and we present high-resolution data on the isotopic composition of the section's organic carbon (δ 13 C org ). This chemostratigraphical record is correlated with previously recognized δ 13 C excursions in the Upper Ordovician–lower Silurian, including the Hirnantian positive isotope carbon excursion (HICE), the early Aeronian positive carbon isotope excursion (EACIE), and the early Sheinwoodian positive carbon isotope excursion (ESCIE). A new positive excursion of high magnitude (~4‰)is discovered in the Telychian Oktavites spiralis Biozone (lower Silurian)and we name it the Sommerodde Carbon Isotope Excursion (SOCIE). The SOCIE appears discernible in δ 13 C carb data from Latvian and Estonian cores but it is not yet widely recognized. However, the magnitude of the excursion within the deep, marine, depositional setting, represented by the Sommerodde-1 core, suggests that the SOCIE reflects a significant event. In addition, the chemostratigraphical record of the Sommerodde-1 core reveals the negative excursion at the transition from the Aeronian to Telychian stages (the ‘Rumba low’), and suggests that the commencement of the EACIE at the base of the Demirastrites triangulatus Biozone potentially is a useful chemostratigraphical marker for the base of the Aeronian Stage

Neuronal precursor cell proliferation in the hippocampus after transient cerebral ischemia: a comparative study of two rat strains using stereological tools

BACKGROUND: We are currently investigating microglial activation and neuronal precursor cell (NPC) proliferation after transient middle cerebral artery occlusion (tMCAo) in rats. This study aimed: (1) to investigate differences in hippocampal NPC proliferation in outbred male spontaneously hypertensive rats (SHRs) and Sprague-Dawley rats (SDs) one week after tMCAo; (2) to present the practical use of the optical fractionator and 2D nucleator in stereological brain tissue analyses; and (3) to report our experiences with an intraluminal tMCAo model where the occluding filament is advanced 22 mm beyond the carotid bifurcation and the common carotid artery is clamped during tMCAo. METHODS: Twenty-three SDs and twenty SHRs were randomized into four groups subjected to 90 minutes tMCAo or sham. BrdU (50 mg/kg) was administered intraperitoneally twice daily on Day 4 to 7 after surgery. On Day 8 all animals were euthanized. NeuN-stained tissue sections were used for brain and infarct volume estimation with the 2D nucleator and Cavalieri principle. Brains were studied for the presence of activated microglia (ED-1) and hippocampal BrdU incorporation using the optical fractionator. RESULTS: We found no significant difference or increase in post-ischemic NPC proliferation between the two strains. However, the response to remote ischemia may differ between SDs and SHRs. In three animals increased post-stroke NPC proliferation was associated with hippocampal ischemic injury. The mean infarct volume was 89.2 ± 76.1 mm(3 )in SHRs and 16.9 ± 22.7 mm(3 )in SDs (p < 0.005). Eight out of eleven SHRs had ischemic neocortical damage in contrast to only one out of 12 SDs. We observed involvement of the anterior choroidal and hypothalamic arteries in several animals from both strains and the anterior cerebral artery in two SHRs. CONCLUSIONS: We found no evidence of an early hippocampal NPC proliferation one week after tMCAo in both strains. Infarction within the anterior choroidal artery could induce hippocampal ischemia and increase NPC proliferation profoundly. NPC proliferation was not aggravated by the presence of activated microglia. Intraluminal tMCAo in SHRs gave a more reliable infarct with neocortical involvement, but affected territories supplied by the anterior cerebral, anterior choroidal and hypothalamic arteries

On Approximately Symmetric Informationally Complete Positive Operator-Valued Measures and Related Systems of Quantum States

We address the problem of constructing positive operator-valued measures (POVMs) in finite dimension $n$ consisting of $n^2$ operators of rank one which have an inner product close to uniform. This is motivated by the related question of constructing symmetric informationally complete POVMs (SIC-POVMs) for which the inner products are perfectly uniform. However, SIC-POVMs are notoriously hard to construct and despite some success of constructing them numerically, there is no analytic construction known. We present two constructions of approximate versions of SIC-POVMs, where a small deviation from uniformity of the inner products is allowed. The first construction is based on selecting vectors from a maximal collection of mutually unbiased bases and works whenever the dimension of the system is a prime power. The second construction is based on perturbing the matrix elements of a subset of mutually unbiased bases. Moreover, we construct vector systems in \C^n which are almost orthogonal and which might turn out to be useful for quantum computation. Our constructions are based on results of analytic number theory.Comment: 29 pages, LaTe

A mouse model of the schizophrenia-associated 1q21.1 microdeletion syndrome exhibits altered mesolimbic dopamine transmission

Abstract 1q21.1 hemizygous microdeletion is a copy number variant leading to eightfold increased risk of schizophrenia. In order to investigate biological alterations induced by this microdeletion, we generated a novel mouse model (Df(h1q21)/+) and characterized it in a broad test battery focusing on schizophrenia-related assays. Df(h1q21)/+ mice displayed increased hyperactivity in response to amphetamine challenge and increased sensitivity to the disruptive effects of amphetamine and phencyclidine hydrochloride (PCP) on prepulse inhibition. Probing of the direct dopamine (DA) pathway using the DA D1 receptor agonist SKF-81297 revealed no differences in induced locomotor activity compared to wild-type mice, but Df(h1q21)/+ mice showed increased sensitivity to the DA D2 receptor agonist quinpirole and the D1/D2 agonist apomorphine. Electrophysiological characterization of DA neuron firing in the ventral tegmental area revealed more spontaneously active DA neurons and increased firing variability in Df(h1q21)/+ mice, and decreased feedback reduction of DA neuron firing in response to amphetamine. In a range of other assays, Df(h1q21)/+ mice showed no difference from wild-type mice: gross brain morphology and basic functions such as reflexes, ASR, thermal pain sensitivity, and motor performance were unaltered. Similarly, anxiety related measures, baseline prepulse inhibition, and seizure threshold were unaltered. In addition to the central nervous system-related phenotypes, Df(h1q21)/+ mice exhibited reduced head-to tail length, which is reminiscent of the short stature reported in humans with 1q21.1 deletion. With aspects of both construct and face validity, the Df(h1q21)/+ model may be used to gain insight into schizophrenia-relevant alterations in dopaminergic transmission

Devonian Rise in Atmospheric Oxygen Correlated to the Radiations of Terrestrial Plants and Large Predatory Fish

The evolution of Earth’s biota is intimately linked to the oxygenation of the oceans and atmosphere. We use the isotopic composition and concentration of molybdenum (Mo) in sedimentary rocks to explore this relationship. Our results indicate two episodes of global ocean oxygenation. The first coincides with the emergence of the Ediacaran fauna, including large, motile bilaterian animals, ca. 550-560 million year ago (Ma), reinforcing previous geochemical indications that Earth surface oxygenation facilitated this radiation. The second, perhaps larger, oxygenation took place around 400 Ma, well after the initial rise of animals and, therefore, suggesting that early metazoans evolved in a relatively low oxygen environment. This later oxygenation correlates with the diversification of vascular plants, which likely contributed to increased oxygenation through the enhanced burial of organic carbon in sediments. It also correlates with a pronounced radiation of large predatory fish, animals with high oxygen demand. We thereby couple the redox history of the atmosphere and oceans to major events in animal evolution.Earth and Planetary SciencesOrganismic and Evolutionary Biolog