A common goodness-of-fit framework for neural population models using marked point process time-rescaling

A critical component of any statistical modeling procedure is the ability to assess the goodness-of-fit between a model and observed data. For spike train models of individual neurons, many goodness-of-fit measures rely on the time-rescaling theorem and assess model quality using rescaled spike times. Recently, there has been increasing interest in statistical models that describe the simultaneous spiking activity of neuron populations, either in a single brain region or across brain regions. Classically, such models have used spike sorted data to describe relationships between the identified neurons, but more recently clusterless modeling methods have been used to describe population activity using a single model. Here we develop a generalization of the time-rescaling theorem that enables comprehensive goodness-of-fit analysis for either of these classes of population models. We use the theory of marked point processes to model population spiking activity, and show that under the correct model, each spike can be rescaled individually to generate a uniformly distributed set of events in time and the space of spike marks. After rescaling, multiple well-established goodness-of-fit procedures and statistical tests are available. We demonstrate the application of these methods both to simulated data and real population spiking in rat hippocampus. We have made the MATLAB and Python code used for the analyses in this paper publicly available through our Github repository at https://github.com/Eden-Kramer-Lab/popTRT.This work was supported by grants from the NIH (MH105174, NS094288) and the Simons Foundation (542971). (MH105174 - NIH; NS094288 - NIH; 542971 - Simons Foundation)Published versio

Electronic properties of the novel 4d metallic oxide SrRhO3

The novel 4d perovskite compound SrRhO3 was investigated by isovalent doping studies. The solubility limits of Ca and Ba onto Sr-site were below 80% and 20%, respectively. Although SrRhO3 was chemically compressed, approximately 5.7% by the Ca doping, no significant influence was observed on the magnetic and electrical properties.Comment: To be published in a special issue of Physica B (the proceedings of LT23

Assessment of cardiac ischaemia and viability: role of cardiovascular magnetic resonance

Over the past years, cardiovascular magnetic resonance (CMR) has proven its efficacy in large clinical trials, and consequently, the assessment of function, viability, and ischaemia by CMR is now an integrated part of the diagnostic armamentarium in cardiology. By combining these CMR applications, coronary artery disease (CAD) can be detected in its early stages and this allows for interventions with the goal to reduce complications of CAD such as infarcts and subsequently chronic heart failure (CHF). As the CMR examinations are robust and reproducible and do not expose patients to radiation, they are ideally suited for repetitive studies without harm to the patients. Since CAD is a chronic disease, the option to monitor CAD regularly by CMR over many decades is highly valuable. Cardiovascular magnetic resonance also progressed recently in the setting of acute coronary syndromes. In this situation, CMR allows for important differential diagnoses. Cardiovascular magnetic resonance also delineates precisely the different tissue components in acute myocardial infarction such as necrosis, microvascular obstruction (MVO), haemorrhage, and oedema, i.e. area at risk. With these features, CMR might also become the preferred tool to investigate novel treatment strategies in clinical research. Finally, in CHF patients, the versatility of CMR to assess function, flow, perfusion, and viability and to characterize tissue is helpful to narrow the differential diagnosis and to monitor treatmen

New physics effects on top quark spin correlation and polarization at the LHC: a comparative study in different models

Extensions of the Standard Model often predict new chiral interactions for top quark, which will contribute to top quark spin correlation and polarization in $t\bar{t}$ production at the LHC. In this work, under the constraints from the current Tevatron measurements, a comparative study of the spin correlation and polarization is performed in three new physics models: the minimal supersymmetric model without R-parity (RPV-MSSM), the third-generation enhanced left-right model and the axigluon model. We find that the polarization asymmetry may be enhanced to the accessible level in all these models while the correction to the spin correlation may be detectable in the axigluon model and the RPV-MSSM with $\lambda"$ couplings.Comment: Version in PRD (figs updated and discussions added

Massive Hyper-Kahler Sigma Models and BPS Domain Walls

With the non-Abelian Hyper-Kahler quotient by U(M) and SU(M) gauge groups, we give the massive Hyper-Kahler sigma models that are not toric in the N=1 superfield formalism. The U(M) quotient gives N!/[M! (N-M)!] (N is a number of flavors) discrete vacua that may allow various types of domain walls, whereas the SU(M) quotient gives no discrete vacua. We derive BPS domain wall solution in the case of N=2 and M=1 in the U(M) quotient model.Comment: 16 pages, 1 figure, contribution to the Proceedings of the International Conference on "Symmetry Methods in Physics (SYM-PHYS10)" held at Yerevan, Armenia, 13-19 Aug. 200

Walls in supersymmetric massive nonlinear sigma model on complex quadric surface

The Bogomol'nyi-Prasad-Sommerfield (BPS) multiwall solutions are constructed in a massive Kahler nonlinear sigma model on the complex quadric surface, Q^N=SO(N+2)/[SO(N)\times SO(2)] in 3-dimensional space-time. The theory has a non-trivial scalar potential generated by the Scherk-Schwarz dimensional reduction from the massless nonlinear sigma model on Q^N in 4-dimensional space-time and it gives rise to 2[N/2+1] discrete vacua. The BPS wall solutions connecting these vacua are obtained based on the moduli matrix approach. It is also shown that the moduli space of the BPS wall solutions is the complex quadric surface Q^N.Comment: 42 pages, 30 figures, typos corrected, version to appear in PR

Lithium production on a low-mass secondary in a black hole soft X-ray transient

We examine production of Li on the surface of a low-mass secondary in a black hole soft X-ray transient (BHSXT) through the spallation of CNO nuclei by neutrons which are ejected from a hot (> 10 MeV) advection-dominated accretion flow (ADAF) around the black hole. Using updated binary parameters, cross sections of neutron-induced spallation reactions, and mass accretion rates in ADAF derived from the spectrum fitting of multi-wavelength observations of quiescent BHSXTs, we obtain the equilibrium abundances of Li by equating the production rate of Li and the mass transfer rate through accretion to the black hole. The resulting abundances are found to be in good agreement with the observed values in seven BHSXTs. We note that the abundances vary in a timescale longer than a few months in our model. Moreover, the isotopic ratio Li6/Li7 is calculated to be about 0.7--0.8 on the secondaries, which is much higher than the ratio measured in meteorites. Detection of such a high value is favorable to the production of Li via spallation and the existence of a hot accretion flow, rather than an accretion disk corona system in quiescent BHSXT.Comment: 4 pages, 3 figures, and 2 tables, submitted to Astrophyscal Jounal Letter

Noise-Induced Synchronization and Clustering in Ensembles of Uncoupled Limit-Cycle Oscillators

We study synchronization properties of general uncoupled limit-cycle oscillators driven by common and independent Gaussian white noises. Using phase reduction and averaging methods, we analytically derive the stationary distribution of the phase difference between oscillators for weak noise intensity. We demonstrate that in addition to synchronization, clustering, or more generally coherence, always results from arbitrary initial conditions, irrespective of the details of the oscillators.Comment: 6 pages, 2 figure

Pseudogap Behavior of the Nuclear Spin-lattice Relaxation Rate in FeSe Probed by 77^{77}Se-NMR

We conducted $^{77}$Se-nuclear magnetic resonance studies of the iron-based superconductor FeSe in magnetic fields of 0.6 to 19 T to investigate the superconducting and normal-state properties. The nuclear spin-lattice relaxation rate divided by the temperature $(T_1T)^{-1}$ increases below the structural transition temperature $T_\mathrm{s}$ but starts to be suppressed below $T^*$, well above the superconducting transition temperature $T_\mathrm{c}(H)$, resulting in a broad maximum of $(T_1T)^{-1}$ at $T_\mathrm{p}(H)$. This is similar to the pseudogap behavior in optimally doped cuprate superconductors. Because $T^*$ and $T_\mathrm{p}(H)$ decrease in the same manner as $T_\mathrm{c}(H)$ with increasing $H$, the pseudogap behavior in FeSe is ascribed to superconducting fluctuations, which presumably originate from the theoretically predicted preformed pair above $T_\mathrm{c}(H)$.Comment: 10 pages, 4 figure