Short-Term Memory Trace in Rapidly Adapting Synapses of Inferior Temporal Cortex

Visual short-term memory tasks depend upon both the inferior temporal cortex (ITC) and the prefrontal cortex (PFC). Activity in some neurons persists after the first (sample) stimulus is shown. This delay-period activity has been proposed as an important mechanism for working memory. In ITC neurons, intervening (nonmatching) stimuli wipe out the delay-period activity; hence, the role of ITC in memory must depend upon a different mechanism. Here, we look for a possible mechanism by contrasting memory effects in two architectonically different parts of ITC: area TE and the perirhinal cortex. We found that a large proportion (80%) of stimulus-selective neurons in area TE of macaque ITCs exhibit a memory effect during the stimulus interval. During a sequential delayed matching-to-sample task (DMS), the noise in the neuronal response to the test image was correlated with the noise in the neuronal response to the sample image. Neurons in perirhinal cortex did not show this correlation. These results led us to hypothesize that area TE contributes to short-term memory by acting as a matched filter. When the sample image appears, each TE neuron captures a static copy of its inputs by rapidly adjusting its synaptic weights to match the strength of their individual inputs. Input signals from subsequent images are multiplied by those synaptic weights, thereby computing a measure of the correlation between the past and present inputs. The total activity in area TE is sufficient to quantify the similarity between the two images. This matched filter theory provides an explanation of what is remembered, where the trace is stored, and how comparison is done across time, all without requiring delay period activity. Simulations of a matched filter model match the experimental results, suggesting that area TE neurons store a synaptic memory trace during short-term visual memory

Ultralight vector dark matter search using data from the KAGRA O3GK run

Among the various candidates for dark matter (DM), ultralight vector DM can be probed by laser interferometric gravitational wave detectors through the measurement of oscillating length changes in the arm cavities. In this context, KAGRA has a unique feature due to differing compositions of its mirrors, enhancing the signal of vector DM in the length change in the auxiliary channels. Here we present the result of a search for U(1)B−L gauge boson DM using the KAGRA data from auxiliary length channels during the first joint observation run together with GEO600. By applying our search pipeline, which takes into account the stochastic nature of ultralight DM, upper bounds on the coupling strength between the U(1)B−L gauge boson and ordinary matter are obtained for a range of DM masses. While our constraints are less stringent than those derived from previous experiments, this study demonstrates the applicability of our method to the lower-mass vector DM search, which is made difficult in this measurement by the short observation time compared to the auto-correlation time scale of DM

Search for eccentric black hole coalescences during the third observing run of LIGO and Virgo

Despite the growing number of confident binary black hole coalescences observed through gravitational waves so far, the astrophysical origin of these binaries remains uncertain. Orbital eccentricity is one of the clearest tracers of binary formation channels. Identifying binary eccentricity, however, remains challenging due to the limited availability of gravitational waveforms that include effects of eccentricity. Here, we present observational results for a waveform-independent search sensitive to eccentric black hole coalescences, covering the third observing run (O3) of the LIGO and Virgo detectors. We identified no new high-significance candidates beyond those that were already identified with searches focusing on quasi-circular binaries. We determine the sensitivity of our search to high-mass (total mass M>70 M⊙) binaries covering eccentricities up to 0.3 at 15 Hz orbital frequency, and use this to compare model predictions to search results. Assuming all detections are indeed quasi-circular, for our fiducial population model, we place an upper limit for the merger rate density of high-mass binaries with eccentricities 0<e≤0.3 at 0.33 Gpc−3 yr−1 at 90\% confidence level

On the polyhedral volume ratios VA/VB in perovskites ABX³.

This paper presents analytical expressions for the calculation of ratios of cation coordination polyhedra volumes (VA/VB) for perovskites ABX³ of the Stokes–Howard diagram directly from atomic coordinates. We show the advantages of quantifying perovskite structure distortion with polyhedral volume ratios rather than with tilting angles, and discuss why space groups with multiple crystallographically inequivalent A or B sites (I4/mmm, Immm, P42/nmcetc.) are much less common than those with a single A and B site (I4/mcm, R c, Pnmaetc.). Analysis of crystallographic data for approximately 1300 perovskite structures of oxides, halides and chalcogenides from the Inorganic Crystal Structure Database revealed that the most highly distorted perovskites belong to the space group Pnma and formally lower-symmetry perovskites (I2/m, I2/a) are less distorted geometrically. Critical values of the VA/VB ratios for the most common phase transitions Pnma↔I4/mcm and Pnma↔R c are estimated to be 4.85 with the possible intermediate space group Imma stable in the very narrow range of VA/VB 4.8–4.9. Transitions to post-perovskite CaIrO3-type structures may be expected for VA/VB < 3.8. © 2007, International Union of Crystallograph

Mixed conductivity, thermal expansion and defect chemistry of A-site deficient LaNi(0.5)Ji(0.5)O(3-delta).

This work is focused on the analysis of defect chemistry and partial electronic and oxygen ionic conductivities of A-site deficient La1-xNi0.5Ti0.5O3-delta (x = 0.05 and 0.10). The orthorhombic-to-rhombohedral phase transition was monitored by means of dilatometry and high-temperature X-ray diffractometry. The average thermal expansion coefficients vary in the range (8.5-13.0) x 10(-6) K-1, increasing with temperature and A-site deficiency. The ion transference numbers determined by the Faradaic efficiency measurements are lower than 0.1% at 900-975 degrees C in air. Activation energies of the oxygen ionic conductivity at 897-977 degrees C are 430 and 220 kJ/mol for x = 0.05 and 0.10, respectively. Atomistic simulation demonstrated high stability of ternary defect clusters formed by the vacant sites in the A-sublattice, oxygen vacancies and W, cations, which leads to a very low level of mixed conductivity. © 2007, Elsevier Ltd

Prognostic roles of obstructive sleep apnea syndrome and right ventricular dysfunction in heart failure patients with preserved ejection

Abstract Funding Acknowledgements Type of funding sources: None. Objective. To study the prognostic roles of obstructive sleep apnea syndrome (OSAS) and right ventricular dysfunction in the development of heart failure (HF) progression in patients with preserved ejection fraction (HFpEF) during the 12-month follow-up period. Methods. The severity of obstructive breathing disorders during sleep was assessed by the apnea/hypopnea index (AHI). A total of 86 men, median age of 62.0 (41.0; 78.0) years with moderate and severe OSAS (with AHI &amp;gt; 15 per hour) and HF of NYHA class I-III with baseline LVEF of 60% [52; 65]% were enrolled in the study. All patients had the abdominal obesity (WC &amp;gt; 92 cm), body mass index exceeded 30 kg/m2. Serum levels of NT-proBNP were measured using ELISA at baseline. Two-dimensional transthoracic echocardiography with assessment of right ventricular function and 6-minute walk test were performed at baseline and at 12 months. Results. At 12 months of follow-up period all patients were divided into 2 groups: group 1 (n = 33) comprised patients with HF progression, group 2 (n = 53) without it. The concentration of NT-proBNP at baseline was higher by 18% in group 1 than in group 2 (p = 0.024; 338 [168; 678] vs. 278 [177; 815] pg/mL, respectively). The median values of AHI (p &amp;lt; 0.0001) were 46.0 [20.6; 85] per hour in group 1 and 24.0 [21.0; 28.0] per hour in group 2. In group 1 than in group 2 fractional change in the area of the right ventricle (ΔSRV) was less by 9.1% (p = 0.031; 40 [35; 47] vs. 44 [40; 47]%, respectively) and right ventricular myocardial function index (RVSWI, Tey index) was less by 8% (p = 0.022; 0.23 [0.22; 0.25] vs. 0.25 [0.24; 0.26], respectively). Based on ROC-analysis, AHI ≥33.5 episodes per hour (sensitivity 75.8%, specificity 67.9%, AUC = 0.732; p &amp;lt; 0.0001), ΔSRV ≤18.6% (sensitivity 75.8%, specificity 54.7%, AUC = 0.62; p = 0.047) and NT-proBNP ≥311 pg/mL (sensitivity 63.6%, specificity 73.6%, AUC = 0.645; p &amp;lt; 0.0001) were identified as a cut-off values predicting the development of HF progression. The combined evaluation of NT-proBNP and AHI increased the predictive value of the analysis (sensitivity of 82.6%, specificity of 77.1%, and AUС of 0.821; p &amp;lt; 0.0001). Conclusion. Our data suggest that NT-proBNP, AHI and ΔSRV may be used as a diagnostic biomarker for HF progression in patients with preserved ejection fraction (HFpEF) during the 12-month follow-up period. The combined use of NT-proBNP and AHI demonstrated higher diagnostic sensitivity and specificity for prediction of unfavorable course of HF. </jats:sec

Prognostic value of soluble ST2 biomarker in heart failure patients with obstructive sleep apnea syndrome

Abstract Funding Acknowledgements Type of funding sources: None. Objective. To analyze the relationships between soluble ST2 (sST2) levels, apnea/hypopnea index (AHI) and echocardiographic parameters in heart failure patients with preserved ejection fraction (HFpEF) and to evaluate prognostic values of sST2 in the development of adverse cardiac events (ASE) during the 12-month follow-up period. Methods. A total of 86 men, median age of 62.0 (41.0; 78.0) years with obstructive sleep apnea syndrome (OSAS) and HF of NYHA class I-III with baseline LVEF of 60% [52; 65]% were enrolled in the study. The severity of obstructive breathing disorders during sleep was assessed by AHI. Serum levels of NT-proBNP and sST2 were measured using ELISA at baseline. Two-dimensional transthoracic echocardiography with assessment of right ventricular (RV) function and 6-minute walk test (6MWT) were performed at baseline. Results. The values of AHI significantly correlated with body mass index (r = 0.362), left atrial volume (r = 0.570), fractional change in the area of the RV (r=-0.527), RV myocardial function index (r=-0.377), NT-proBNP (r = 0.611), 6MWT (r=-0.511), RV anterior wall thickness (r = 0,472), while the levels of sST2 significantly correlated with LV remodeling parameters: LVEF (r =-0.301), end-systolic volume (r =0.453), end-diastolic volume (r =0.396), end-systolic dimension (r = 0.373), end-diastolic dimension (r =0.288). Based on ROC-analysis, sST2 ≥29.67 ng/mL (sensitivity 63.6%, specificity 73.6%, AUC = 0.645; p &amp;lt; 0.0001) were identified as a cut-off values predicting the development of ACE. At 12 months of follow-up period all patients were divided into 2 groups according to cut-off values of sST2: group 1 (n = 29) comprised patients with sST2 ≥29.67 ng/mL, group 2 (n = 42) comprised patients with sST2 &amp;lt;29.67 ng/mL. The median baseline values of sST2 were 41.39 [33.31; 50.99] ng/mL in group 1, and 22.18 [20.64; 25.5] ng/mL in group 2. The concentrations of NT-proBNP did not differ between the groups. During the 12-month follow-up period in group 1 the rate of ACE was 29.7% cases, and 5.2% in group 2, respectively. According to Kaplan-Meier analysis, a higher sST2 levels was associated with a higher frequency of ACE during 12 months of follow-up (р&amp;lt;0.0001). Univariable and multivariable Cox regression analyses showed sST2 concentrations were significantly associated with ACE (odds ratio 2.25, 95%CI: 2.06 to 3.29, p &amp;lt; 0.001), when adding AHI and LV myocardial mass index improved reclassification of risk stratification (odds ratio 3,28, 95%CI: 3,09 to 4,49, p &amp;lt; 0.001, AUC of 0.945, percent of cases correctly classified of 90.14 %). However, NT-proBNP addition had a limited effect on risk stratification. Conclusion. Our data suggest that sST2 may be used as a diagnostic biomarker for prediction of ACE in patients with HFpEF and OSAS during the 12-month follow-up period. The combined evaluation of sST2, AHI and LV myocardial mass index values demonstrated higher diagnostic sensitivity and specificity for prediction of ACE. </jats:sec

Oxygen permeability, stability and electrochemical behavior of Pr2NiO4+δ-based materials.

The high-temperature electronic and ionic transport properties, thermal expansion and stability of dense Pr2NiO4+δ Pr2Ni0.9Fe0.1O4+δ ceramics have been appraised in comparison with K2NiF4-type lanthanum nickelate. Under oxidizing conditions, the extensive oxygen uptake at temperatures below 1073-1223 K leads to reversible decomposition of Pr2NiO4-based solid solutions into Ruddlesden-Popper type Pr4Ni3O10 and praseodymium oxide phases. The substitution of nickel with copper decreases the oxygen content and phase transition temperature, whilst the incorporation of iron cations has opposite effects. Both types of doping tend to decrease stability in reducing atmospheres as estimated from the oxygen partial pressure dependencies of total conductivity and Seebeck coefficient. The steady-state oxygen permeability of Pr2NiO4+δ ceramics at 1173-1223 K, limited by both surface-exchange kinetics and bulk ionic conduction, is similar to that of La2NiO4+δ. The phase transformation on cooling results in considerably higher electronic conductivity and oxygen permeation, but is associated also with significant volume changes revealed by dilatometry. At 973-1073 K, porous Pr2Ni0.8Cu0.2O4+δ electrodes deposited onto lanthanum gallate-based solid electrolyte exhibit lower anodic overpotentials compared to Pr2Ni0.8Cu0.2O4+δ, whilst cathodic reduction decreases their performance. © 2007, Springer. The original publication is available at www.springerlink.co