julilili42/papers huggingface dataset:
Electric crosstalk impairs spatial resolution of multi-electrode arrays in retinal implants
2011-06-15

Active multi-electrode arrays are used in vision prostheses, including optic nerve cuffs and cortical and retinal implants for stimulation of neural tissue. For retinal implants, arrays with up to 1500 electrodes are used in clinical trials. The ability to convey information with high spatial resolution is critical for these applications. To assess the extent to which spatial resolution is impaired by electric crosstalk, finite-element simulation of electric field distribution in a simplified passive tissue model of the retina is performed. The effects of electrode size, electrode spacing, distance to target cells, and electrode return configuration (monopolar, tripolar, hexagonal) on spatial resolution is investigated in the form of a mathematical model of electric field distribution. Results show that spatial resolution is impaired with increased distance from the electrode array to the target cells. This effect can be partly compensated by non-monopolar electrode configurations and larger electrode diameters, albeit at the expense of lower pixel densities due to larger covering areas by each stimulation electrode. In applications where multi-electrode arrays can be brought into close proximity to target cells, as presumably with epiretinal implants, smaller electrodes in monopolar configuration can provide the highest spatial resolution. However, if the implantation site is further from the target cells, as is the case in suprachoroidal approaches, hexagonally guarded electrode return configurations can convey higher spatial resolution.
Behavioral and In Vivo Electrophysiological Evidence for Presymptomatic Alteration of Prefrontostriatal Processing in the Transgenic Rat Model for Huntington Disease
2011-06-15

Cognitive decline precedes motor symptoms in Huntington disease (HD). A transgenic rat model for HD carrying only 51 CAG repeats recapitulates the late-onset HD phenotype. Here, we assessed prefrontostriatal function in this model through both behavioral and electrophysiological assays. Behavioral examination consisted in a temporal bisection task within a supra-second range (2 vs.8 s), which is thought to involve prefrontostriatal networks. In two independent experiments, the behavioral analysis revealed poorer temporal sensitivity as early as 4 months of age, well before detection of overt motor deficits. At a later symptomatic age, animals were impaired in their temporal discriminative behavior. In vivo recording of field potentials in the dorsomedial striatum evoked by stimulation of the prelimbic cortex were studied in 4- to 5-month-old rats. Input/output curves, paired-pulse function, and plasticity induced by theta-burst stimulation (TBS) were assessed. Results showed an altered plasticity, with higher paired-pulse facilitation, enhanced short-term depression, as well as stronger long-term potentiation after TBS in homozygous transgenic rats. Results from the heterozygous animals mostly fell between wild-type and homozygous transgenic rats. Our results suggest that normal plasticity in prefrontostriatal circuits may be necessary for reliable and precise timing behavior. Furthermore, the present study provides the first behavioral and electrophysiological evidence of a presymptomatic alteration of prefrontostriatal processing in an animal model for Huntington disease and suggests that supra-second timing may be the earliest cognitive dysfunction in HD.
Development of a Fluorescence Resonance Energy Transfer Peptide Library Technology for Detection of Protease Contaminants in Protein-Based Raw Materials Used in Diagnostic Assays
2011-06-15

Protease impurities in raw materials used in enzyme immunoassays can impair assay performance. This risk may be greatly decreased if incoming protein-based raw materials are controlled for protease impurities or if protease inhibitors are used in the assay formulations. As many different proteases might occur in protein raw materials, it is desirable to have a general test for protease contamination. With the help of a fluorescence resonance energy transfer peptide library containing about 2.5 million peptides, we have succeeded in establishing such a system, with sensitivity in the nanogram range for known proteases. Protease contamination was found to differ between different raw materials and was correlated with assay performance. Protease activity in contaminated raw materials could be suppressed to various degrees with different chemical inhibitors or by thermal treatment. This technology is suited for the control of incoming protein-based raw materials used for enzyme immunoassays, as well as for the optimization of the use of protein inhibitors or thermal treatment of protein-based raw materials for the inactivation of proteases.
Testing proposals for the Yang-Mills vacuum wavefunctional by measurement of the vacuum
2011-06-16

We review a method, suggested many years ago, to numerically measure the relative amplitudes of the true Yang-Mills vacuum wavefunctional in a finite set of lattice-regulated field configurations. The technique is applied in 2+1 dimensions to sets of abelian plane wave configurations of varying amplitude and wavelength,\\nand sets of non-abelian constant configurations. The results are compared to the predictions of several proposed versions of the Yang-Mills vacuum wavefunctional that have appeared in the literature. These include (i) a suggestion in temporal gauge due to Greensite and Olejník; (ii) the “new variables” wavefunction put forward\\nby Karabali, Kim, and Nair; (iii) a hybrid proposal combining features of the temporal gauge and new variables wavefunctionals; and (iv) Coulomb gauge wavefunctionals developed by Reinhardt and co-workers, and by Szczepaniak and co-workers. We find that wavefunctionals which simplify to a “dimensional reduction” form at large scales, i.e. which have the form of a probability distribution for two-dimensional lattice gauge theory, when evaluated on long-wavelength configurations, have the\\noptimal agreement with the data.
NEAR WELL‐SCALE HETEROGENEITIES IN A KHUFF OUTCROP EQUIVALENT (SAIQ PLATEAU, AL JABAL AL AKHDAR, SULTANATE OF OMAN)
2011-06-16

The Middle Permian to Lower Triassic Khuff Formation is one of the world's most prolific hydrocarbon reservoirs. This study is part of a research project on Khuff outcrop equivalents whose overall aim is to investigate the reservoir architecture on different scales. The present paper focuses on heterogeneities in Khuff‐equivalent grainstones at the near well scale. An outcrop in the Oman Mountains, where the Khuff‐equivalent Saiq and Mahil Formations are exposed in an area 1800 m long by 100 m high, was studied to map lateral and vertical depositional heterogeneities. The investigated section represents parts of three third‐order sequences: the upper part of Khuff sequence (KS)3 (grain‐dominated), the whole of KS2 (mud‐dominated), and the lower part of KS1 (grain‐dominated). Real‐Time Kinematic GPS, satellite imagery, outcrop gamma‐ray and digitized sedimentary logs were used for outcrop description and were integrated into a three‐dimensional digital outcrop model. The resulting 3D facies model indicates that the apparently simple, layer‐cake geometry of the grainstone reservoir facies shows pinching and swelling with a standard deviation of 12.75% of bed thickness. These thickness variations may influence volume calculations during reservoir assessments. The heterogeneities of grainstone bodies are represented by compositional (ooid, peloid or intraclast‐dominated) and grain‐size variations. Muddy event beds at the cm‐scale were mapped out in detail in a 200 × 40 m outcrop window and together form a dense network of potential baffles to fluid flow. The thickness of these beds varies significantly due to syndepositional erosion. An important conclusion of this near well‐scale study is that the perceived simple, layer‐cake Khuff‐equivalent succession in the study area is in fact heterogeneous in mud‐rich deposits, while grain‐rich deposits extend over a wide area with some thickness variations. These findings can be directly applied in Khuff subsurface correlation and modelling attempts.
Palaeomagnetic remanences in high-grade metamorphic rocks of the Everest region: indication for Late Miocene crustal doming
2011-06-16

High-grade metamorphic rocks of the upper amphibolite to granulite facies in the Higher Himalayan crystalline (HHC) were studied for their appropriateness for palaeomagnetic investigations. Sampling and fieldwork was accomplished on a south–north transect at ∼87°E in the Khumbu region south of Everest. Paragenesis of iron-sulphides and oxides was found to be variable due to different source rocks and metamorphic conditions in this area. Unblocking temperature ranges, isothermal remanence acquisition, low-temperature magnetic properties and microscopic observations confirm the presence of pyrrhotite and magnetite. Two remanence components were separated with unblocking temperature intervals of 250–330 °C and 370–550 °C, which can be attributed to characteristic remanent magnetizations (ChRM) of monoclinic pyrrhotite (ChRMpyr) and magnetite (ChRMmag), respectively. Mainly the ChRMpyr showed a consistent demagnetization behaviour, probably residing in pyrrhotite particles within the single domain to pseudo-single domain range. Normal and reverse polarities were observed, partly co-existing within the unblocking spectrum of single specimens; this (i) supports a thermoremanent (TRM) origin of the ChRMpyr and (ii) indicates that the time span of remanence acquisition was long enough to average out palaeosecular variation. The age of the ChRMpyr can be related to the last metamorphic cooling event at the Early to Late Miocene boundary (16 Ma). The ChRMmag is probably a secondary chemical or thermochemical remanence acquired by hydrothermal processes during retrogression. ChRMpyr and ChRMmag directions are similar suggesting that pyrrhotite and magnetite were magnetized approximately contemporaneously. Separation of the sampling area into three sectors reveals a south–north trend with (i) variable block rotations in the southernmost part close to the Main Central Thrust (five sites), (ii) no rotation in the area between Lukla and Namche (10 sites) and (iii) a significant clockwise rotation (N= 5 sites, D/I= 42.3°/29.4°, k= 20.7, α95= 17.2°) along the Imja Khola north of Namche. We interpret the clockwise rotation as an apparent rotation due to tilting by crustal doming in the Everest region. This doming obviously occurred north of a fault zone located at around Namche and was not affecting the region south of it. The clockwise sense of the apparent vertical-axis rotation indicates that the area north of Namche is located at the western side of the dome structure where westward tilting around a subhorizontal axis occurred (best fit: tilt direction 277°, tilt angle 51°).
Abashian-Booth-Crowe Effect in Basic Double-Pionic Fusion: A New Resonance?
2011-06-17

We report on an exclusive and kinematically complete high-statistics measurement of the basic double-pionic fusion reaction pn→dπ(0)π(0) over the full energy region of the ABC effect, a pronounced low-mass enhancement in the ππ-invariant mass spectrum. The measurements, which cover also the transition region to the conventional t-channel ΔΔ process, were performed with the upgraded WASA detector setup at COSY. The data reveal the Abashian-Booth-Crowe effect to be uniquely correlated with a Lorentzian energy dependence in the integral cross section. The observables are consistent with a narrow resonance with m=2.37 GeV, Γ≈70 MeV and I(J(P))=0(3(+)) in both pn and ΔΔ systems. Necessary further tests of the resonance interpretation are discussed.
Interleukin 23 Expression in Pyoderma Gangrenosum and Targeted Therapy With Ustekinumab
2011-06-17

Our data provide evidence of an IL-23-dominated inflammatory infiltrate in PG. This might specify a new concept for PG pathophysiology and suggests a possibility for using ustekinumab as a therapeutic agent in this disease.
The ciliopathy-associated protein homologs RPGRIP1 and RPGRIP1L are linked to cilium integrity through interaction with Nek4 serine/threonine kinase
2011-06-17

Recent studies have established ciliary dysfunction as the underlying cause of a broad range of multi-organ phenotypes, known as 'ciliopathies'. Ciliopathy-associated proteins have a common site of action in the cilium, however, their overall importance for ciliary function differs, as implied by the extreme variability in ciliopathy phenotypes. The aim of this study was to gain more insight in the function of two ciliopathy-associated protein homologs, RPGR interacting protein 1 (RPGRIP1) and RPGRIP1-like protein (RPGRIP1L). Mutations in RPGRIP1 lead to the eye-restricted disease Leber congenital amaurosis, while mutations in RPGRIP1L are causative for Joubert and Meckel syndrome, which affect multiple organs and are at the severe end of the ciliopathy spectrum. Using tandem affinity purification in combination with mass spectrometry, we identified Nek4 serine/threonine kinase as a prominent component of both the RPGRIP1- as well as the RPGRIP1L-associated protein complex. In ciliated cells, this kinase localized to basal bodies, while in ciliated organs, the kinase was predominantly detected at the ciliary rootlet. Down-regulation of NEK4 in ciliated cells led to a significant decrease in cilium assembly, pointing to a role for Nek4 in cilium dynamics. We now hypothesize that RPGRIP1 and RPGRIP1L function as cilium-specific scaffolds that recruit a Nek4 signaling network which regulates cilium stability. Our data are in line with previously established roles in the cilium of other members of the Nek protein family and define NEK4 as a ciliopathy candidate gene.
Reflex and Tonic Autonomic Markers for Risk Stratification in Patients With Type 2 Diabetes Surviving Acute Myocardial Infarction
2011-06-17

OBJECTIVE Diabetic postinfarction patients are at increased mortality risk compared with nondiabetic postinfarction patients. In a substantial number of these patients, diabetic cardiac neuropathy already preexists at the time of the infarction. In the current study we investigated if markers of autonomic dysfunction can further discriminate diabetic postinfarction patients into low- and high-risk groups. RESEARCH DESIGN AND METHODS We prospectively enrolled 481 patients with type 2 diabetes who survived acute myocardial infarction (MI), were aged ≤80 years, and presented in sinus rhythm. Primary end point was total mortality at 5 years of follow-up. Severe autonomic failure (SAF) was defined as coincidence of abnormal autonomic reflex function (assessed by means of heart rate turbulence) and of abnormal autonomic tonic activity (assessed by means of deceleration capacity of heart rate). Multivariable risk analyses considered SAF and standard risk predictors including history of previous MI, arrhythmia on Holter monitoring, insulin treatment, and impaired left ventricular ejection fraction (LVEF) ≤30%. RESULTS During follow-up, 83 of the 481 patients (17.3%) died. Of these, 24 deaths were sudden cardiac deaths and 21 nonsudden cardiac deaths. SAF identified a high-risk group of 58 patients with a 5-year mortality rate of 64.0% at a sensitivity level of 38.0%. Multivariately, SAF was the strongest predictor of mortality (hazard ratio 4.9 [95% CI 2.4–9.9]), followed by age ≥65 years (3.4 [1.9–5.8]), and LVEF ≤30% (2.6 [1.5–4.4]). CONCLUSIONS Combined abnormalities of autonomic reflex function and autonomic tonic activity identifies diabetic postinfarction patients with very poor prognoses.
Thymoquinone‐induced platelet apoptosis
2011-06-17

Abstract Thymoquinone (TQ) is a nutrient with anticarcinogenic activity that stimulates suicidal death of tumor cells. Moreover, TQ triggers suicidal death of erythrocytes or eryptosis, an effect at least partially due to increase in cytosolic Ca 2+ activity and ceramide formation. The present experiments explored whether TQ influences apoptosis of blood platelets. Cell membrane scrambling was determined utilizing Annexin V binding to phosphatidylserine exposing platelets, cytosolic Ca 2+ activity utilizing Fluo 3‐AM fluorescence, caspase activity utilizing immunofluorescence and Western blotting of active caspase‐3 and inactive procaspase‐3, mitochondrial potential utilizing DiOC 6 fluorescence and ceramide by FACS analysis of ceramide‐binding antibodies. A 30 min exposure to TQ (≥5 μM) was followed by Annexin V binding, paralleled by caspase activation, increase of cytosolic Ca 2+ activity, mitochondrial depolarization, and ceramide formation. P‐selectin exposure and integrin α IIb β 3 activation did not increase in response to TQ. Nominal absence of extracellular Ca 2+ blunted but did not fully abolish the TQ‐induced activation of caspase‐3. The effects of TQ on platelets are significantly abolished with phosphoinositide‐3 kinase (PI3K) inhibitor wortmannin and G‐protein coupled receptor (GPCR) inhibitor pertussis toxin treatment prior to TQ stimulation. In conclusion, TQ triggers suicidal death of blood platelets in a PI3K‐dependent manner, possibly through a GPCR family receptor; an effect paralleled by increase of cytosolic Ca 2+ activity, ceramide formation, mitochondrial depolarization, and caspase‐3 activation. J. Cell. Biochem. 112: 3112–3121, 2011. © 2011 Wiley Periodicals, Inc.
No Elevated Plasma Catecholamine Levels during Sleep in Newly Diagnosed, Untreated Hypertensives
2011-06-17

The sympatho-adrenergic system is highly involved in regulating sleep, wake and arousal states, and abnormalities in this system are regarded as a key factor in the development and progression of arterial hypertension. While hypertension is associated with a hyperadrenergic state during wakefulness, the effect of hypertension on plasma-catecholamine levels during sleep is not yet known. Twelve young participants with newly diagnosed, untreated hypertension and twelve healthy controls slept for 7 hours in the sleep laboratory. Before and after sleep, subjects rested in a supine position for 3-h periods of wakefulness. We sampled blood at a fast rate (1/10 min) and monitored blood pressure and heart rate continuously. We show that plasma NE and E levels did not differ between hypertensives and normotensive during sleep as well as before and after sleep. Blood pressure was higher in hypertensives, reaching the largest group difference in the morning after sleep. Unlike in the normotensives, in the hypertensive participants the morning rise in blood pressure did not correlate with the rise in catecholamine levels at awakening. Our results suggest that hypertension in its early stages is not associated with a strong hyperadrenergic state during sleep. In showing a diminished control of blood pressure through sympatho-adrenergic signals in hypertensive participants, our data point towards a possible involvement of dysfunctional sleep-related blood pressure regulation in the development of hypertension.
A tall-spined ornithopod dinosaur from the Early Cretaceous of Salas de los Infantes (Burgos, Spain)
2011-06-19

A tall-spined ornithopod dinosaur from the Pinilla de los Moros Formation (Upper Hauterivian-Lower Barremian) of Salas de los Infantes (Burgos, Spain) is described. The material consists of seven associated axial remains, including five middle dorsal vertebrae, a fragmentary neural spine and a dorsal rib, from a single medium-sized individual. This material was previously referred to Iguanodon cf. fittoni. It is characterised by having a high dorsal neurapophysis that is approximately 4.5 times the height of the centrum. The elongation and vertical orientation of the dorsal neural spines allow it to be distinguished from other ornithopods from the Wealden of Europe, including Hypselospinus and Barilium from the Valanginian, and Iguanodon and Mantellisaurus from the Barremian-Aptian. The material is here referred to Iguanodontia indet. because it is so incomplete, but it is potentially a distinct taxon. Among the ornithopods, only Ouranosaurus and the hadrosaurid Hypacrosaurus possess higher dorsal neural spines. Un dinosaure ornithopode à haute épine neurale provenant de la Formation Pinilla de los Moros (Hauterivien supérieur-Barrémien inférieur) de Salas de los Infantes (Burgos, Espagne) est décrit ici. Le matériel consiste en sept restes associés du squelette axial, y compris cinq vertèbres dorsales moyennes, une épine neurale fragmentaire et une côte dorsale, appartenant probablement à un seul individu de taille moyenne. Ce matériel a été auparavant rapporté à Iguanodon cf. fittoni. Il est caractérisé par une neurapophyse allongée, environ quatre fois et demie plus haute que la hauteur du centrum. La longueur et l'orientation verticale de l'épine neurale des vertèbres dorsales permettent de le différencier d'autres ornithopodes des faciès wealdiens d'Europe, y compris Hypselospinus et Barilium du Valanginien, Iguanodon et Mantellisaurus du Barrémien-Aptien. Il est ici rapporté à Iguanodontia indet. de part sa nature fragmentaire, mais représente potentiellement un nouveau taxon. Parmi les ornithopodes, seuls Ouranosaurus et l'hadrosauridé Hypacrosaurus possèdent des épines neurales dorsales plus hautes.
Neural substrates of cognitive capacity limitations
2011-06-20

Cognition has a severely limited capacity: Adult humans can retain only about four items “in mind”. This limitation is fundamental to human brain function: Individual capacity is highly correlated with intelligence measures and capacity is reduced in neuropsychiatric diseases. Although human capacity limitations are well studied, their mechanisms have not been investigated at the single-neuron level. Simultaneous recordings from monkey parietal and frontal cortex revealed that visual capacity limitations occurred immediately upon stimulus encoding and in a bottom-up manner. Capacity limitations were found to reflect a dual model of working memory. The left and right halves of visual space had independent capacities and thus are discrete resources. However, within each hemifield, neural information about successfully remembered objects was reduced by adding further objects, indicating that resources are shared. Together, these results suggest visual capacity limitation is due to discrete, slot-like, resources, each containing limited pools of neural information that can be divided among objects.
Optical evidence for intermolecular coupling in mixed films of pentacene and perfluoropentacene
2011-06-20

We present optical absorption spectra of mixed films of pentacene (PEN) and\\nperfluoropentacene (PFP) grown on SiO2. We investigated the influence of\\nintermolecular coupling between PEN and PFP on the optical spectra by analyzing\\nsamples with five different mixing ratios of PFP:PEN with variable angle\\nspectroscopic ellipsometry (VASE) and differential reflectance spectroscopy\\n(DRS). The data show how the spectral shape is influenced by changes in the\\nvolume ratio of the two components. By comparison with the pure film spectra an\\nattempt is made to distinguish transitions due to intermolecular coupling\\nbetween PEN and PFP from transitions caused by interactions of PEN (PFP) with\\nother molecules of the same type. We observe a new transition at 1.6 eV which\\nis not found in the pure film spectra and which we assign to coupling of PFP\\nand PEN.\\n