Study of high transverse momentum charged particle suppression in heavy ion collisions at LHC

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2012.Cataloged from PDF version of thesis.Includes bibliographical references.The charged particle spectrum at large transverse momentum (PT), dominated by hadrons originating from parton fragmentation, is an important observable for studying the properties of the hot, dense medium produced in high-energy heavy-ion collisions. The study of the modifications of the PT spectrum in PbPb compared to pp collisions at the same collision energy can shed light on the detailed mechanism by which hard partons lose energy traversing the medium. In this thesis, the transverse momentum spectra of charged particles in pp and PbPb collisions at [square root of]Snn = 2.76 TeV measured up to PT = 100 GeV/c with the CMS experiment at the Large Hadron Collider (LHC) are presented. In the transverse momentum range PT = 5-10 GeV/c, the charged particle yield in the most central PbPb collisions is suppressed by up to a factor of 7 compared to the pp yield scaled by the number of incoherent nucleon-nucleon collisions. At higher PT, this suppression is significantly reduced, approaching roughly a factor of 2 for particles with PT in the range PT = 40-100 GeV/c. A simple modeling of the parton energy loss applied to the PYTHIA Monte-Carlo (MC) reveals that the charged particle spectrum with the pQCD-motivated fractional parton energy loss can describes the shape of the measured suppression well in the range PT = 5-100 GeV/c.by Andre Sungho Yoon.Ph.D

Model complexes for active sites of diiron metalloproteins, dioxygen reactivity and water effects

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2004.Includes bibliographical references.(cont.) tetrairon(II) cubane complex was identified and structurally characterized. Chapter 4: Synthesis and Characterization of [Fe₂...CR)]³⁺ and [Fe₂...CR)]³⁺ Complexes with Carboxylate-Rich Metal Coordination Environment as Models for Diiron Centers in Oxygen-Dependent Non-Heme Enzymes. Utilizing hydrogen bonding interactions and sterically bulky carboxylates, synthetic routes were developed to prepare the mononuclear iron(II) complexes with the vacant coordination sites for O₂ binding. Reactions of such complexes with O₂ resulted in rare asymmetric complexes having an [Fe₂...CR)]³⁺ or [Fe₂...CR)]³⁺ unit. These diiron(III) complexes with carboxylate-rich metal coordination environments reproduce the diiron(III) cores housed in four-helix bundles found in nature. Compound 3, which replicates the [Fe₂...CR)] core of sMMOH[ox], shares several physical properties with the enzyme, electronic transitions, Mossbauer spectra, and magnetic exchange interactions. On the other hand, the structure of 4, ([mu]-oxo)([mu]-carboxylato)diiron(III) complex, mimics the diiron(III) sites of RNR-R2. The electronic and Mbssbauer spectral transitions of 4 are typical of diiron(III) complexes with an Fe-O-Fe moiety. Magnetic exchange coupling interaction between the two iron atoms is within the expected range for oxo-bridged diiron(III) sites. These results demonstrate how the diiron(III) structures in different metalloproteins, namely, the [mu]-oxo cores of RNR-R2 and the [mu]-dihydroxo unit in MMOH, can be replicated by subtle changes in ligand composition ...Chapter 1: Modeling Studies for Diiron Sites with Carboxylate Rich Coordination Environments in Dioxygen-Dependent Non-Heme Enzymes: Compounds Synthesized, Understanding Achieved, and Directions to Take. Our efforts to better understand of dioxygen-dependent diiron proteins with carboxylate-rich coordination environments through synthesis of small model complexes are summarized. We describe both not only the significant results that have contributed toward this goal, but also the rationale behind how one generation of model systems gave way to the next. Chapter 2: Mechanistic Studies of the Oxidative N-Dealkylation of a Benzyl Group Substrates Tethered to Carboxylate-Bridged Diiron(II) Complexes, [Fe₂...Bn₂en)₂]. Hammett and intramolecular kinetic isotope effect (KIE[intra]) analyses for oxidative N-dealkylation of [Fe₂...Bn₂en)₂] rule out previously proposed concerted and hydrogen atom transfer mechanisms. We conclude that the reaction operates through single-electron transfer from the non-bonding electron pair of the amine substrate to the dioxygen-generated intermediate, followed by proton transfer and rearrangement. Chapter 3. Synthesis, Characterization, and Dioxygen Reactivity of Tetracarboxylate-Bridged Diiron(II) Complexes with Coordinated Substrates. The synthesis and characterization of [Fe₂...L₂] complexes, where L is benzylamine (BA) or 4-methoxybenzylamine (BAP[p-OMe]), and their oxygenation are described. Various methods, including resonance Raman (rR) and electron paramagnetic resonance (EPR) spectroscopy, have been applied to understand the mechanism and the intermediates involved. In addition, upon dissolution of the tetracarboxylate-bridged diiron(II) complex in methanol, an asymmetricby Sungho Yoon.Ph.D

Risk Factors for Failure of Initial Intravenous Immunoglobulin Treatment in Kawasaki Disease

The aims of this study were to determine the occurrence and variables associated with the initial intravenous immunoglobulin (IVIG) treatment failure in Kawasaki disease (KD) and to categorize differences in clinical characteristics between responders and nonresponders to initial IVIG treatment. Patients were classified into two groups. Group A included 33 patients who received a single dose of IVIG treatment and responded. Group B included 18 patients who received more than two doses of IVIG due to failure of the initial treatment. The mean duration of fever after initial treatment in group B was significantly longer than it was in group A. In group B, we found that higher bilirubin, aspartate aminotransferase (AST), polymorphonuclear cells (PMN) (%), and lower platelet values at baseline were independent predictors of persistent or recurrent fever in patients with KD. Coronary artery abnormalities were found in 8 patients (44.4%) in group B and in two patients (6.1%) in group A. We found that abnormal liver function tests and a lower platelet count at baseline were possible predictors of nonresponders to IVIG in patients with KD. There is a need for a prospective study focused on baseline hepatobiliary parameters

Bis(4,4′′-difluoro-1,1′:3′,1′′-terphenyl-2′-carboxyl­ato-κO)bis­(3,5-dimethyl-1H-pyrazole-κN 2)manganese(II)

In the title compound, [Mn(C19H11F2O2)2(C5H8N2)2], the Mn2+ cation is coordinated by the N atoms of two 3,5-dimethyl­pyrazole ligands and carboxyl­ate O atoms from two 4,4′′-difluoro-1,1′:3′,1′′-terphenyl-2′-carboxyl­ato ligands, forming an MnN2O2 polyhedron with a slightly distorted tetra­hedral coordination geometry. Two intra­molecular hydrogen bonds are observed between the carboxyl­ate and pyrazole ligands. The combined influence of the sterically hindered carboxyl­ate ligands and the intra­molecular hydrogen-bonding inter­actions stabilizes the title compound with a low coordination number of four. In the crystal, weak C—H⋯F and C—H⋯O hydrogen bonds are observed

In situ-prepared composite materials of PEDOT: PSS buffer layer-metal nanoparticles and their application to organic solar cells

We report an enhancement in the efficiency of organic solar cells via the incorporation of gold (Au) or silver (Ag) nanoparticles (NPs) in the hole-transporting buffer layer of poly(3,4- ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), which was formed on an indium tin oxide (ITO) surface by the spin-coating of PEDOT:PSS-Au or Ag NPs composite solution. The composite solution was synthesized by a simple in situ preparation method which involved the reduction of chloroauric acid (HAuCl4) or silver nitrate (AgNO3) with sodium borohydride (NaBH4) solution in the presence of aqueous PEDOT:PSS media. The NPs were well dispersed in the PEDOT:PSS media and showed a characteristic absorption peak due to the surface plasmon resonance effect. Organic solar cells with the structure of ITO/PEDOT:PSS-Au, Ag NPs/poly(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PC61BM)/LiF/Al exhibited an 8% improvement in their power conversion efficiency mainly due to the enlarged surface roughness of the PEDOT:PSS, which lead to an improvement in the charge collection and ultimately improvements in the short-circuit current density and fill factor. © 2012 Woo et al.1

Adjoint Trapping: A New Phenomenon at Strong 't Hooft Coupling

Adding matter of mass m, in the fundamental representation of SU(N), to N=4 supersymmetric Yang-Mills theory, we study ``generalized quarkonium'' containing a (s)quark, an anti(s)quark, and J massless (or very light) adjoint particles. At large 't Hooft coupling $\lambda$ >> 1, the states of spin <= 1 are surprisingly light (Kruczenski et al., hep-th/0304032) and small (hep-th/0312071) with a J-independent size of order $\sqrt{\lambda}/m$. This ``trapping'' of adjoint matter in a region small compared with its Compton wavelength and compared to any confinement scale in the theory is an unfamiliar phenomenon, as it does not occur at small $\lambda$. We explore adjoint trapping further by considering the limit of large J. In particular, for J >> $\sqrt{\lambda}$ >> 1, we expect the trapping phenomenon to become unstable. Using Wilson loop methods, we show that a sharp transition, in which the generalized quarkonium states become unbound (for massless adjoints) occurs at $J \simeq 0.22 \sqrt{\lambda}$. If the adjoint scalars of N=4 are massive and the theory is confining (as, for instance, in N=1* theories) then the transition becomes a cross-over, across which the size of the states changes rapidly from ~$\sqrt{\lambda}/m$ to something of order the confinement scale ~ $\Lambda^{-1}$.Comment: Clarified transition with a better figure and improved presentation; added careful discussion of the small regime of validity of the Born-Oppenheimer computation and adjusted some remarks appropriately; also added two reference

MMP-3 Contributes to Nigrostriatal Dopaminergic Neuronal Loss, BBB Damage, and Neuroinflammation in an MPTP Mouse Model of Parkinson\u27s Disease

The present study examined whether matrix metalloproteinase-3 (MMP-3) participates in the loss of dopaminergic (DA) neurons in the nigrostriatal pathway in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of Parkinson\u27s disease with blood brain barrier (BBB) damage and infiltration of peripheral immune cells. Tyrosine hydroxylase (TH) immunostaining of brain sections from MPTP-treated mice showed that MPTP induced significant degeneration of nigrostriatal DA neurons. Moreover, FITC-labeled albumin detection and immunostaining revealed that MPTP caused damage to the BBB and increased the number of ED-1- and CD-3-immunopositive cells in the substantia nigra (SN). Genetic ablation of MMP-3 reduced the nigrostriatal DA neuron loss and improved motor function. This neuroprotective effect afforded by MMP-3 deletion was associated with the suppression of BBB disruption and a decrease in the number of ED-1- and CD-3-immunopositive cells in the SN. These data suggest that MMP-3 could play a crucial role in neurodegenerative diseases such as PD in which BBB damage and neuroinflammation are implicated

New Concept of a Surgical Hospitalist: Early Experience of Managing the Admission, Critical Care, Trauma Surgery Team

The demand for hospitalists is increasing due to decreasing numbers of clinical residents and increased concerns regarding patient safety. However, several limitations in the surgical hospitalist role exist. The personnel of the surgical hospitalist, rapid response team (RRT), surgical critical care, and trauma surgery teams were unified under the admission, critical care, and trauma surgery (ACTs) team at this institution. The ACTs target are patients with severe disease not undergoing general postoperative course, or patients with the potential for severe conversion. Two surgical intensivists are on duty once a week and oversee the intensive care unit (ICU), the back-up treatment of critically ill patients, and the immediate treatment of trauma patients. ACTs also participate in the surgical RRT and select patients with a high probability of severe exacerbation. Between 2019–2021, the cardiopulmonary resuscitation incidence per 1,000 hospitalized patients in the surgical department decreased significantly from 0.81 to 0.55. From March to December 2021, the ACTs team were involved with 101 of 158 surgical patients admitted to the ICU: 62 with postoperative status, 29 with severe trauma, and 10 transferred to the ICU via RRT screening. Based on our experience, the role of the ACTs team can help improve patient safety