DETERMINANTS ANALYSIS OF GROWTH RATE IN PRIVATE EQUITY MARKET

This paper focuses on the analysis of modeling the growth rate of private equity investments and determining its related underlying factors. We calculate the growth rate based on the formula presented by Takahashi and Alexander (2001) and then model the growth rate to be related to the cumulative contribution rate and growth rate of price and earnings(with some lags) in public equity market. First we test the reliability of the model constructed by Hoek using the data of US private equity market from 1990 to 2002. Then we update the dataset up to 2006 for both US and European markets and redo the ordinary linear regression to test the reliability of our newly constructed model. We find that Hoek?s model is not quite reliable and persuasive in associating the growth rate of US private equity market to excess stock market return. In contrast, based on the derivation of change in net asset value (NAV) and results of statistical tests, the growth rate of US and European private equity markets seem to only depend on changes in the price of public equity markets but with the lag of one year for the US market and three years for European market

xFx_F Dependence of Drell-Yan Transverse Moemtum Broadening

We analyze $x_F$ dependence of Drell-Yan transverse momentum broadening in hadron-nucleus collisions. In terms of generalized factorization theorem, we show that the $x_F$ dependence of transverse momentum broadening, $\Delta < q_T^2 > (x_F)$, can be calculated in perturbative QCD. We demonstrate that $\Delta (x_F)$ is a good observable for studying the effects of initial-state multiple scattering and extracting quark-gluon correlation functions.Comment: 10 pages, 3 figure

Sneutrino DM in the NMSSM with inverse seesaw mechanism

In supersymmetric theories like the Next-to-Minimal Supersymmetric Standard Model (NMSSM), the lightest neutralino with bino or singlino as its dominant component is customarily taken as dark matter (DM) candidate. Since light Higgsinos favored by naturalness can strength the couplings of the DM and thus enhance the DM-nucleon scattering rate, the tension between naturalness and DM direct detection results becomes more and more acute with the improved experimental sensitivity. In this work, we extend the NMSSM by inverse seesaw mechanism to generate neutrino mass, and show that in certain parameter space the lightest sneutrino may act as a viable DM candidate, i.e. it can annihilate by multi-channels to get correct relic density and meanwhile satisfy all experimental constraints. The most striking feature of the extension is that the DM-nucleon scattering rate can be naturally below its current experimental bounds regardless of the higgsino mass, and hence it alleviates the tension between naturalness and DM experiments. Other interesting features include that the Higgs phenomenology becomes much richer than that of the original NMSSM due to the relaxed constraints from DM physics and also due to the presence of extra neutrinos, and that the signatures of sparticles at colliders are quite different from those with neutralino as DM candidate.Comment: 33 page

Global Adaptive Generative Adjustment

Many traditional signal recovery approaches can behave well basing on the penalized likelihood. However, they have to meet with the difficulty in the selection of hyperparameters or tuning parameters in the penalties. In this article, we propose a global adaptive generative adjustment (GAGA) algorithm for signal recovery, in which multiple hyperpameters are automatically learned and alternatively updated with the signal. We further prove that the output of our algorithm directly guarantees the consistency of model selection and the asymptotic normality of signal estimate. Moreover, we also propose a variant GAGA algorithm for improving the computational efficiency in the high-dimensional data analysis. Finally, in the simulated experiment, we consider the consistency of the outputs of our algorithms, and compare our algorithms to other penalized likelihood methods: the Adaptive LASSO, the SCAD and the MCP. The simulation results support the efficiency of our algorithms for signal recovery, and demonstrate that our algorithms outperform the other algorithms

Text Categorization based on Clustering Feature Selection

AbstractIn this paper, we discuss a text categorization method based on k-means clustering feature selection. K-means is classical algorithm for data clustering in text mining, but it is seldom used for feature selection. For text data, the words that can express correct semantic in a class are usually good features. We use k-means method to capture several cluster centroids for each class, and then choose the high frequency words in centroids as the text features for categorization. The words extracted by k-means not only can represent each class clustering well, but also own high quality for semantic expression. On three normal text databases, classifiers based on our feature selection method exhibit better performances than original classifiers for text categorization

Explaining the DAMPE data with scalar dark matter and gauged U(1)Le−LμU(1)_{L_e-L_\mu} interaction

Inspired by the peak structure observed by recent DAMPE experiment in $e^+e^-$ cosmic-ray spectrum, we consider a scalar dark matter (DM) model with gauged $U(1)_{L_e-L_\mu}$ symmetry, which is the most economical anomaly-free theory to potentially explain the peak by DM annihilation in nearby subhalo. We utilize the process $\chi \chi \to Z^\prime Z^\prime \to l \bar{l} l^\prime \bar{l}^\prime$, where $\chi$, $Z^\prime$, $l^{(\prime)}$ denote the scalar DM, the new gauge boson and $l^{(\prime)} =e, \mu$, respectively, to generate the $e^+e^-$ spectrum. By fitting the predicted spectrum to the experimental data, we obtain the favored DM mass range $m_\chi \simeq 3060^{+80}_{-100} \, {\rm GeV}$ and $\Delta m \equiv m_\chi - m_{Z^\prime} \lesssim 14 \, {\rm GeV}$ at $68\%$ Confidence Level (C.L.). Furthermore, we determine the parameter space of the model which can explain the peak and meanwhile satisfy the constraints from DM relic abundance, DM direct detection and the collider bounds. We conclude that the model we consider can account for the peak, although there exists a tension with the constraints from the LEP-II bound on $m_{Z^\prime}$ arising from the cross section measurement of $e^+e^- \to Z^{\prime\ast} \to e^+ e^-$.Comment: 15 pages, 4 figure

The Endangerment of Electrical Shocks on Humans

In Deutschland dürfen Reizstoffsprühgeräte (RSG) nur mit Zulassung hergestellt und verkauft werden, wenn sie als Selbstverteidigungsmittel gegen Menschen gedacht sind. Nach der Änderung des Waffenrechts im Jahr 2003 hat die Fraunhofer-Gesellschaft die Zuständigkeit der Prüfung der Reizstoffsprühgeräte abgegeben. Es gab seitdem keine Richtlinien für die Messeinrichtungen. Aktuell ist die Physikalisch-Technische Bundesanstalt für die Zulassung zuständig. Im ersten Teil dieser Arbeit wurde eine Anforderung für Reizstoffsprühgeräte erstellt. Sie ermöglicht neue Zulassungen von RSG durch die PTB. Das Prüfverfahren wurde getestet. Der zweite Teil der Arbeit fokussiert sich auf die Untersuchung der Gefahr des Herzkammerflimmerns von Elektroimpulsgeräten (EIG) und deren neue Bewertungsverfahren. EIG gehören zu den bekanntesten Personenschutzgeräten und dürfen in Deutschland verkauft werden. Sie übertragen wie ein TASER© Impulse in den Körper der Zielperson. Die Wirkung von Elektroimpulsgeräten soll die direkte oder indirekte Erregung einer großen Masse von Zellen im Körper durch den Strom hervorrufen. Zu den erregbaren Zellen zählen die Nervenzellen und die Muskelzellen. Die Gefährdung eines EIG wird auch von seinem Strom verursacht. Ein anatomisches menschliches CAD-Körpermodell wurde nach der Anforderung dieser Arbeit angepasst. Das Modell wurde in einer Finite-Elemente-Methode-Modellierung (FEM) eingesetzt. Mit der Modellierung kann die Stromverteilung im Körper berechnet werden, welche als Mittel der Bewertung der Gefährlichkeit eines möglichen vom EIG verursachten Herzkammerflimmerns verwendet wird. Um das computerbasierte Modell zu erstellen, werden die elektrischen Eigenschaften des menschlichen Körpers benötigt. Die Leitfähigkeit von Muskelgewebe wurde im Rahmen dieser Arbeit im Hochspannungsbereich gemessen. Die Feldstärkeabhängigkeit der Leitfähigkeit wurde nachgewiesen. Deren gemessene Kennlinie wurde zum Aufbau des Gleichungssystems in das FEM-Modell eingesetzt. Drei physikalische Modelle wurden in dieser Arbeit verglichen, nämlich ein elektrisches quasistatisches Modell, ein frequenzabhängiges Modell und ein Modell mit einer feldstärkeabhängigen Leitfähigkeit. Die Kenngrößen Ausgangsspannung, Elektrodenabstand und Elektrodendurch-messer eines EIG führten über das FEM-Modell zu einer Aussage der Stromdichte auf der Herzoberfläche. Das Modell mit einer feldstärkeabhängigen Leitfähigkeit wurde zusammen mit einem Nervenzellenmodell als das Berechnungstool in dem neuen Bewertungsverfahren verwendet. Das neue Verfahren kann auch die Wirksamkeit von EIG evaluieren. Um die zukünftige komplizierte Berechnung mit dem FEM-Modell zu vermeiden, wurde eine Lookup-Tabelle erstellt.In Germany, irritant gas spraying devices (RSG) may only be manufactured and sold with approval if they are intended as a self-defense device against humans. Following the amendment of the law in 2003, the Fraunhofer-Gesellschaft has given up responsibility for testing irritant gas spraying devices. Since then, there have been no guidelines for the measuring devices. Currently, the Physikalisch-Technische Bundesanstalt (PTB) is responsible for the approval. In the first part of this work, a requirement for irritant gas spraying devices has been established. It enables new approvals of RSG by the PTB. The test method was established. The second part of the thesis focuses on the investigation of the risk of ventricular fibrillation of electric shock devices (EIG) and their new evaluation procedures. EIG are among the most well-known personal defense equipment and can be sold in Germany. They transmit impulses into the body of the target person like a TASER©. The effect of EIG is intended to cause the direct or indirect stimulation of a large mass of cells especially nerve cells and muscle cells in the body through the current. The threat of an EIG is caused by its current. An anatomical CAD human model was adapted to the requirement of this work. The model was used in a finite element method modeling (FEM). This modeling can be applied to calculate the distribution of current in the body, which is used as a means of assessing the danger of any potential ventricular fibrillation caused by the EIG. To create the computer-based model, the electrical properties of the human body are required. The conductivity of muscle tissue was measured in the context of this work in the high voltage range. The field strength dependence of the conductivity was detected. The measured characteristic curve was used to build the equation system in the FEM model. Three physical models were compared in this work: an electrical quasi-static model, a frequency-dependent model and a model with a field-strength-dependent conductivity. The output voltage, the electrode spacing and the electrode diameter of an EIG led to a statement of the current density on the heart surface using the FEM model. The model with a field-strength-dependent conductivity was used together with a neuron model as the calculation tool in the new test method. The new method can also evaluate the effectiveness of EIG. To avoid a complicated calculation with the FEM model in the future, a lookup table has been created