Trapping in the random conductance model

We consider random walks on $\Z^d$ among nearest-neighbor random conductances which are i.i.d., positive, bounded uniformly from above but whose support extends all the way to zero. Our focus is on the detailed properties of the paths of the random walk conditioned to return back to the starting point at time $2n$. We show that in the situations when the heat kernel exhibits subdiffusive decay --- which is known to occur in dimensions $d\ge4$ --- the walk gets trapped for a time of order $n$ in a small spatial region. This shows that the strategy used earlier to infer subdiffusive lower bounds on the heat kernel in specific examples is in fact dominant. In addition, we settle a conjecture concerning the worst possible subdiffusive decay in four dimensions.Comment: 21 pages, version to appear in J. Statist. Phy

Aplicarea sistemului de hidrochirurgie și a plasmajetului în debridarea toracoscopică a cavității pleurale la copii cu fibrinotorax

Toracoscopia a devenit o modalitate favorizată în tratamentul empiemului pleural la copii. Cu toate acestea, factorii care afectează rezultatul administrării toracoscopice rămân neclari. Scopul studiului este de a demonstra eficiența sistemului de hidrochirurgie "Versajet" și a unității de plasmă "Plasmajet" în tratamentul toracoscopic al copiilor cu complicații pleurale ale pneumoniei. MATERIALE SI METODE. În perioada 2015-2017, la Spitalul de Copii Speransky din Moscova, 377 copii cu pneumonie au fost tratați, la 62 pacienți (16,45%) din 377 am efectuat drenajul cavității pleurale, 14 pacienți cu vârste cuprinse între 1,6 și 15 ani (în medie, 3,2 ± 3,8 ani) cu empiem pleural au fost operați. S-a efectuat decorticarea pulmonară toracoscopică cu sistem de hidrochirurgie (Versajet-2). Sistemul hidrochirurgical este un instrument chirurgical bazat pe impactul jetului de apă de mare viteză asupra țesuturilor necrotice și inflamate, combinând avantajele debridării țesuturilor moi și evacuarea acestora prin pulsarea jetului de apă. Designul tubului de evacuare și apropierea acestuia de jetul lichid creează un vacuum local, care îndepărtează efectiv fibrina și conținutul lichid prin efectul Bernulli. Consimțământul informat a fost obținut de la toți părinții înainte de operare, iar procedura însăși a fost aprobată de comitetul de etică locală. REZULTATE. Recuperarea și reabilitarea fără particularități au fost în 13 cazuri. La un pacient cu empiem al cavității pleurale pe dreapta și leziune organică severă a sistemului nervos central a perioadei postoperatorii după o toracoscopie convențională complicată de recurența empiemului pleural.Retoracoscopia cu debridarea cavității pleurale de către sistemul de hidrochirurgie efectuată la șase zile după operația inițială, a avut rezultate satisfăcătoare. În cazul hemoragiei intraoperatorii, a fost efectuată coagularea plasmei de argon, obținându-se aerostasie completă la 2 pacienți și hemostază - la 1 pacient. Durata medie de funcționare a fost de 90 de minute (± 15 minute). Drenajul cavității pleurale este eliminat în ziua a 3-a sau a 4-a după operație. Copiii externați în ziua a 10-a (± 1,2 zile). Examinarea cu ultrasunete și cu raze X la patru luni după intervenția chirurgicală a confirmat absența inflamației în parenchimul pulmonar și reexpansarea plină pulmonară la toți pacienții. CONCLUZIE. Aplicarea sistemului hidrochirurgical în timpul toracoscopiei asigură o debridare sigură și eficientă a cavității pleurale, decorticările plămânului fiind fără deteriorarea severă a parenchimului pulmonar și crearea condițiilor pentru reabilitarea precoce a plămânilor compromiși.Thoracoscopy became a favored modality in pediatric pleural empyema treatment. However, factors affecting outcome of thoracos- copic management remain unclear. The purpose of the study is to demonstrate efficiency of hydrosurgery system "Versajet" and plasma unit "Plasmajet" in thoracoscopic treatment of children with pleural complications of pneumonia. MATERIALS AND METHODS. During the period of 2015-2017 at the Speransky Children’s Hospital in Moscow 377 children with pneumonia were treated, in 62 patients (16.45%) of 377 we perform drainage of pleural cavity, 14 patients from 1.6 to 15 years of age (on average, 3.2 ± 3.8 years old) with pleural empyema were operated. Thoracoscopic lung decortication with hydrosurgery system (Versajet-2) was performed. Hydrosurgery system is a surgical instrument based on impact of high-speed jet of water on necrotic and inflamed tissues, combining the advantages of soft tissues debridement and evacuation them by pulsating water jet. Design of the evacuation tube and its proximity to liquid jet creates a local vacuum, which effectively removes fibrin and liquid contents by Ber- nulli effect. Informed consent was obtained from all parents before operation, and procedure itself received approval from the local ethics committee. RESULTS. Recovery and rehabilitation was uneventful in 13 cases. In one patient with empyema of right pleural cavity and severe organic lesion of central nervous system postoperative period after conventional toracoscopy complicated by recurrence of pleural empyema. Rethoracoscopy with debridement of pleural cavity by hydrosurgery system performed six days after initial operation, with satisfactory results. In the event of intraoperative air leak or hemorrhage, application of argon plasma coagulation had been performed achieving complete aerostasis in 2 patients and hemostasis - in 1 patient. Average operation time was 90 minutes (± 15 minutes). Drainage of the pleural cavity removed on the 3rd or 4th day after surgery. Children discharged from the hospital on 10th PO day (± 1.2 days). Ultrasound and X-ray examination four months after surgery confirmed the absence of inflammation in the lung parenchyma and full lung reexpansion in all patients. CONCLUSION. Application of hydrosurgycal system during thoracoscopy provides safe and effective debridement of pleural cavity, decortications of the lung without severe damage to the lung parenchyma and create conditions for early rehabilitation of compro- mised lung

Inhibition of Bacterial Conjugation by Phage M13 and Its Protein g3p: Quantitative Analysis and Model

Conjugation is the main mode of horizontal gene transfer that spreads antibiotic resistance among bacteria. Strategies for inhibiting conjugation may be useful for preserving the effectiveness of antibiotics and preventing the emergence of bacterial strains with multiple resistances. Filamentous bacteriophages were first observed to inhibit conjugation several decades ago. Here we investigate the mechanism of inhibition and find that the primary effect on conjugation is occlusion of the conjugative pilus by phage particles. This interaction is mediated primarily by phage coat protein g3p, and exogenous addition of the soluble fragment of g3p inhibited conjugation at low nanomolar concentrations. Our data are quantitatively consistent with a simple model in which association between the pili and phage particles or g3p prevents transmission of an F plasmid encoding tetracycline resistance. We also observe a decrease in the donor ability of infected cells, which is quantitatively consistent with a reduction in pili elaboration. Since many antibiotic-resistance factors confer susceptibility to phage infection through expression of conjugative pili (the receptor for filamentous phage), these results suggest that phage may be a source of soluble proteins that slow the spread of antibiotic resistance genes

Contemporary organizational forms of interaction between the departments of medical universities and urban hospitals

То provide patients with specialized and high-tech medical care is the most important problem of practice healthcare at the present-day stage. This cannot be achieved without searching for new forms of interaction between the departments of medical universities and urban hospitals. The paper evaluates the efficiency of using the professional and teaching staff of the universities and practical healthcare workers in the educational and diagnostic-and-therapeutic process. Analysis of the activity of the University Clinic of Pediatrics and Childhood Infectious Diseases has demonstrated its high effectiveness. This makes it possible to set up similar structural entities on the base of the departments of medical universities and urban hospitals

Development of new technologies in the diagnosis and treatment of childhood diseases at the Moscow Research Institute of Pediatrics and Pediatric Surgery, Ministry of Health ofRussiain2013

The paper presents the 2013 Institute's scientific achievements and developments made within the framework of the State Task in Initiative and Postgraduate Works. It describes the priority developments obtained using technologies in the diagnosis, treatment, prediction, and rehabilitation of childhood diseases with their efficiency being indicated. New progression markers and novel and improved therapeutic options are proposed for introduction; current approaches to preventing disease progression in children at different ages are substantiated

Zircon geochronology of bottom rocks in the central Arctic Ocean: analytical results and some geological implications

In the past few years sampling of deepwater seabed gained an increasingly important role in studying geological structure of the Arctic Ocean. A common concept of virtually uninterrupted pelagic drape in the Amerasia Basin and exclusively ice-rafted nature of all clastic components that occur in bottom sediments was challenged by recent discoveries of bedrock exposures in the sea floor, while correlation of results of analytical study of bottom samples collected by the Russian expeditions in 2000, 2005 and 2007 with bathymetric environments at respective sites suggested that certain dredged and cored coarse rock fragments appeared meaningful for bedrock characterization if even the source sub-pelagic outcrop was not positively documented. The first results of age determinations of detrital zircons that were extracted from coarse fragments of lithic sedimentary rocks resting on the seabed and in the immediate sub-bottom, as well as of zircons from fragments of magmatic/metamorphic rocks and of zircon grains separated directly from sub-pelagic unlithified sediments are in agreement with published interpretations of the Lomonosov Ridge bedrock as composed of Mesozoic terrigenous sequences; the presence of an older Neoproterozoic(?) – Early-Middle Paleozoic basement is also possible. The Mendeleev Rise bedrock, too, is believed to mainly consist of Paleozoic-Early(?) Mesozoic sedimentary superstructure that may locally rest on the Earliest Paleozoic or even older units. Basaltic rocks likely to originate from the High Arctic Large Igneous Province (HALIP) has not so far been found among the collected fragments but limited loose zircon grains probably derived from broadly contemporaneous magmatic products were recorded in sub-pelagic sediment along with dropstones of variably metamorphosed Precambrian mafic and granitoid rocks. INTRODUCTION Great progress in acquisition of new bathymet-ric and geophysical data relevant to understanding the geological structure and history of the Arctic Ocean, including the tectonic nature of enigmatic Central-Arctic bathymetric highs, was achieved in recent years by the Arctic countries through their programs for delineation of respective extended continental shelves. However, only limited direct geological information was obtained on the compo-sition of sub-bottom bedrock concealed by almost continuous drape of young sediments. Only at a few sites can the lithic fragments recovered by bottom sampling be interpreted with sufficient confidence as representing in situ submarine bedrock, while in most cases they are regarded ice rafted debris (IRD) of questionable derivation. In search of provenance of lithic and mineral clastic components in bottom sediments we conducted age determinations on zircon crystals of two categories: (1) extracted from the rock fragments and (2) separated directly from hemipelagic sediments. In this paper we present the results of more than 700 zircon U-Pb age measurements completed before 2012. The samples labeled AF00, AF05, AF07 were collected during MS " Akademik Fedorov " cruises Arctic-2000, 2005, 2007, those marked ALR07 were acquired in 2007 on board NIB (nuclear icebreaker) " Rossiya " , and two specimens designated BC were selected for the analysis from clastic material sampled by RV " Polarstern " in the course of ARK-XXIII/3-2008 cruise