Two-loop matching coefficients for the strong coupling in the MSSM

When relating the strong coupling $\alpha_s$, measured at the scale of the $Z$ boson mass, to its numerical value at some higher energy, for example the scale of Grand Unification, it is important to include higher order corrections both in the running of $\alpha_s$ and the decoupling of the heavy particles. We compute the two-loop matching coefficients for $\alpha_s$ within the Minimal Supersymmetric Standard Model (MSSM) which are necessary for a consistent three-loop evolution of the strong coupling constant. Different scenarios for the hierarchy of the supersymmetric scales are considered and the numerical effects are discussed. We find that the three-loop effects can be as large as and sometimes even larger than the uncertainty induced by the current experimental accuracy of $\alpha_s(M_Z)$.Comment: 22 pages, 8 figures (13 ps/eps-files

Coupled-cluster theory of a gas of strongly-interacting fermions in the dilute limit

We study the ground-state properties of a dilute gas of strongly-interacting fermions in the framework of the coupled-cluster expansion (CCE). We demonstrate that properties such as universality, opening of a gap in the excitation spectrum and applicability of s-wave approximations appear naturally in the CCE approach. In the zero-density limit, we show that the ground-state energy density depends on only one parameter which in turn may depend at most on the spatial dimensionality of the system.Comment: 7 figure

Dimensional Reduction applied to QCD at three loops

Dimensional Reduction is applied to \qcd{} in order to compute various renormalization constants in the \drbar{} scheme at higher orders in perturbation theory. In particular, the $\beta$ function and the anomalous dimension of the quark masses are derived to three-loop order. Special emphasis is put on the proper treatment of the so-called $\epsilon$-scalars and the additional couplings which have to be considered.Comment: 13 pages, minor changes, references adde

The four-loop DRED gauge beta-function and fermion mass anomalous dimension for general gauge groups

We present four-loop results for the gauge beta-function and the fermion mass anomalous dimension for a gauge theory with a general gauge group and a multiplet of fermions transforming according to an arbitrary representation, calculated using the dimensional reduction scheme. In the special case of a supersymmetric theory we confirm previous calculations of both the gauge beta-function and the gaugino mass beta-function.Comment: 44 pages, added references (v2) minor changes (v3

MINSTED fluorescence localization and nanoscopy

We introduce MINSTED, a fluorophore localization and super-resolution microscopy concept based on stimulated emission depletion (STED) that provides spatial precision and resolution down to the molecular scale. In MINSTED, the intensity minimum of the STED doughnut, and hence the point of minimal STED, serves as a movable reference coordinate for fluorophore localization. As the STED rate, the background and the required number of fluorescence detections are low compared with most other STED microscopy and localization methods, MINSTED entails substantially less fluorophore bleaching. In our implementation, 200–1,000 detections per fluorophore provide a localization precision of 1–3 nm in standard deviation, which in conjunction with independent single fluorophore switching translates to a ~100-fold improvement in far-field microscopy resolution over the diffraction limit. The performance of MINSTED nanoscopy is demonstrated by imaging the distribution of Mic60 proteins in the mitochondrial inner membrane of human cells

Enhanced incorporation of subnanometer tags into cellular proteins for fluorescence nanoscopy via optimized genetic code expansion

With few-nanometer resolution recently achieved by a new generation of fluorescence nanoscopes (MINFLUX and MINSTED), the size of the tags used to label proteins will increasingly limit the ability to dissect nanoscopic biological structures. Bioorthogonal (click) chemical groups are powerful tools for the specific detection of biomolecules. Through the introduction of an engineered aminoacyl–tRNA synthetase/tRNA pair (tRNA: transfer ribonucleic acid), genetic code expansion allows for the site-specific introduction of amino acids with “clickable” side chains into proteins of interest. Welldefined label positions and the subnanometer scale of the protein modification provide unique advantages over other labeling approaches for imaging at molecular-scale resolution. We report that, by pairing a new N-terminally optimized pyrrolysyl–tRNA synthetase (chPylRS2020) with a previously engineered orthogonal tRNA, clickable amino acids are incorporated with improved efficiency into bacteria and into mammalian cells. The resulting enhanced genetic code expansion machinery was used to label β-actin in U2OS cell filopodia for MINFLUX imaging with minimal separation of fluorophores from the protein backbone. Selected data were found to be consistent with previously reported high-resolution information from cryoelectron tomography about the cross-sectional filament bundling architecture. Our study underscores the need for further improvements to the degree of labeling with minimal-offset methods in order to fully exploit molecularscale optical three-dimensional resolution

Minimally invasive approach to colorectal tumors - 3 years of experience in a private hospital

Spitalul Privat ”Sanador”, București, România, Al XIII-lea Congres al Asociației Chirurgilor „Nicolae Anestiadi” și al III-lea Congres al Societății de Endoscopie, Chirurgie miniminvazivă și Ultrasonografie ”V.M.Guțu” din Republica MoldovaIntroducere: Abordul minim invaziv al tumorilor colo-rectale reprezintă o preocupare a colectivului Spitalului privat Sanador, în pofida adresabilității crescute a cancerelor în stadii avansate, procentul acestora din totalul intervențiilor chirurgicale pentru această patologie rămânând constant, printr-o atentă selecție a pacienților, care sa beneficieze de avantajele laparoscopiei. Material și metode: Studiul prezent analizează intervențiile chirurgicale pentru tumori colo-rectale efectuate între anii 2016-2018 în Spitalul Sanador București. Din totalul de 214 intervenții chirurgicale pentru patologia colo-rectală, 41 au fost prin abord minim invaziv, reprezentând procentual 20% din totalul intervențiilor pentru această patologie, procentul fiind constant în fiecare din acești ani: 2016 – 13 intervenții prin abord minim invaziv din totalul de 68 (19.11%); 2017 – 17 intervenții prin abord minim invaziv din totalul de 79 (21.5%); 2018 – 11 intervenții chirurgicale prin abord minim invaziv dintr-un total de 57 (19.3%). Rezultate: Cele mai frecvente localizări ale tumorilor pentru care indicația a fost de abord minim invaziv, au fost cele recto-sigmoidiene (28). Selecția pacienților s-a facut după stadializarea preoperatorie, admitându-se ca și abord laparoscopic tumori T1, T2, T3, în rare cazuri T4. În cazul tumorilor avansate, substadializate preoperator, s-a tentat efectuarea a cât mai multor timpi din cadrul rezecției, prin abord minim invaziv, iar cazurile in care anastomozele au fost efectuate extracorporeal nu au fost interpretate ca și conversie. Concluzii: Rezultatele bune se înscriu în rândul celor ale centrelor cu volum și experiența mari în abordarea minim invazivă a tumorilor colo-rectale și constituie premize pentru creșterea procentului de astfel de intervenții în clinica noastră.Introduction: The minimally invasive approach of colorectal tumors is a concern of the Sanador private hospital team, despite the increased addressability of cancers in advanced stages, their percentage of total surgical interventions for this pathology remaining constantly through a careful selection of patients who benefit from the advantages of laparoscopy. Material and methods: The present study examines surgical interventions for colorectal tumors performed between 2016-2018 at Sanador Hospital Bucharest. Of the total of 214 surgical procedures for rectal pathology, 41 were by minimally invasive approach, accounting for 20% of all interventions for this pathology, the percentage being constant in each of these years: 2016-13 interventions through the minimally invasive approach of the total of 68 (19.11%); 2017 - 17 interventions through minimally invasive approach from the total of 79 (21.5%); 2018 - 11 minimally invasive surgical interventions from a total of 57 (19.3%). Results: The most common tumor localizations for which the indication was minimally invasive were the recto-sigmoid (28). Selection of patients was made after preoperative staging, admitting as a laparoscopic approach T1, T2, T3 tumors, in rare cases T4. In the case of advanced tumors, pre-operative substations, it was tempting to perform as many times as possible in the resection through a minimally invasive approach, and the cases in which the anastomoses were performed extracorporeally were not interpreted as conversion. Conclusions: Good results are among those with large volume centers and great experience in the minimally invasive approach of colorectal tumors and are prerequisites for increasing the percentage of such interventions in our clinic

Heat Capacity in Magnetic and Electric Fields Near the Ferroelectric Transition in Tri-Glycine Sulfate

Specific-heat measurements are reported near the Curie temperature ($T_C$~= 320 K) on tri-glycine sulfate. Measurements were made on crystals whose surfaces were either non-grounded or short-circuited, and were carried out in magnetic fields up to 9 T and electric fields up to 220 V/cm. In non-grounded crystals we find that the shape of the specific-heat anomaly near $T_C$ is thermally broadened. However, the anomaly changes to the characteristic sharp $\lambda$-shape expected for a continuous transition with the application of either a magnetic field or an electric field. In crystals whose surfaces were short-circuited with gold, the characteristic $\lambda$-shape appeared in the absence of an external field. This effect enabled a determination of the critical exponents above and below $T_C$, and may be understood on the basis that the surface charge originating from the pyroelectric coefficient, $dP/dT$, behaves as if shorted by external magnetic or electric fields.Comment: 4 Pages, 4 Figures. To Appear in Applied Physics Letters_ January 200

Band structure of SnTe studied by Photoemission Spectroscopy

We present an angle-resolved photoemission spectroscopy study of the electronic structure of SnTe, and compare the experimental results to ab initio band structure calculations as well as a simplified tight-binding model of the p-bands. Our study reveals the conjectured complex Fermi surface structure near the L-points showing topological changes in the bands from disconnected pockets, to open tubes, and then to cuboids as the binding energy increases, resolving lingering issues about the electronic structure. The chemical potential at the crystal surface is found to be 0.5eV below the gap, corresponding to a carrier density of p =1.14x10^{21} cm^{-3} or 7.2x10^{-2} holes per unit cell. At a temperature below the cubic-rhombohedral structural transition a small shift in spectral energy of the valance band is found, in agreement with model predictions.Comment: 4 figure

Quantum dynamics of phase transitions in broken symmetry λϕ4\lambda \phi^4 field theory

We perform a detailed numerical investigation of the dynamics of broken symmetry $\lambda \phi^4$ field theory in 1+1 dimensions using a Schwinger-Dyson equation truncation scheme based on ignoring vertex corrections. In an earlier paper, we called this the bare vertex approximation (BVA). We assume the initial state is described by a Gaussian density matrix peaked around some non-zero value of $$, and characterized by a single particle Bose-Einstein distribution function at a given temperature. We compute the evolution of the system using three different approximations: Hartree, BVA and a related 2PI-1/N expansion, as a function of coupling strength and initial temperature. In the Hartree approximation, the static phase diagram shows that there is a first order phase transition for this system. As we change the initial starting temperature of the system, we find that the BVA relaxes to a new final temperature and exhibits a second order phase transition. We find that the average fields thermalize for arbitrary initial conditions in the BVA, unlike the behavior exhibited by the Hartree approximation, and we illustrate how$$ and $$depend on the initial temperature and on the coupling constant. We find that the 2PI-1/N expansion gives dramatically different results for$$.Comment: 28 pages, 21 figures; ver 2 -- additional comments on the nature of the phase transition in 1+1 dimension