Folosirea stentului uretral în tratamenntul chirurgical a hipospadiasului la copii

Summary Introducing uretrhral stent allowed us to decrease the esenţial number of complication after a uretrhral plastic specially for the patients more that 12-13 years old and adolescentes. I decreased two times numbers of external urethral orifice stenosis and reduced the formation of the urthral fistula for 25% of patients. Introducere. Hipospadiasul se raportează la malformaţiile congenitale a uretrei şi este foarte răspândit, incidenţa fiind de 1:200-1:300 de nou-născuţi (băieţei). Există mai multe clasificări ale hipospadiasului, bazate preponderent pe schimbarea poziţiei (ectopiei) orificiului uretral extern. În practica noastră, pentru aprecierea tacticii de tratament, inclusiv a celei chirurgicale, apelăm la repartizarea pacienţilor în trei loturi: cu hipospadias distal, proximal şi hipospadias fară hipospadias. La hipospadiasul distal se referă formele glandulare, coronare, subcoronare şi formele joase peniene, fără curbarea penisului. Acestor pacienţi li se efectuează plastia de uretră întro singură etapă. Hipospadiasul proximal include formele peniene, scrotale şi perineale îmbinate cu deformare pronunţată a corpurilor cavernoase. Acestor pacenţi li se aplică plastia de uretră într-o singură etapă - înlăturarea hordei cicatrizante şi formarea uretrei de tip Dakket sau Kayanaghi. Hipospadiasul fără hipospadias se atestă în cazurile de curbare a penisului fără ectopia orificiului extern al uretrei. Tactica de tatament operativ depinde de gradul de curbare şi se recurge la plastia de uretră de tip Dakket, Nesbit. Exigenţele cosmetice contemporane dictează formarea orificiului extern uretral la apexul glandului penian. Totuşi ţesuturile spongioase ale glandului penian sunt sensibile la mobilizarea largă şi la incizia operatorie. Edemul postoperator şi creşterea pronunţată a presiunii în segmentul glandular al neouretrei deseori duce la formarea fistulelor uretrocutane, mai des întâlnite la copiii de după 14-15 ani. Din aceste motive majoritatea chirurgilor preferă formarea meatului extern al uretrei la nivelul şanţului balanic. Plastia de uretră se efectuează pe o sondă Nelaton, corespunzătoare după mărime vârstei bolnavului, care, pe parcursul perioadei postoperatorii, deseori provoacă uretrite şi cistite. Materiale şi metodă. O alternativă de derivare a urinei este epicistostomia troacară sau cea deschisă şi stentul uretral. În perioada 1999 - 2006 au fost trataţi 104 copii cu hipospadias cu vârsta de la 2 şi pâna la 18 ani, cu hipospadias distal şi proximal. În primul lot (68) au intrat copii operaţi până la vârsta de 12 ani, cu derivarea urinei postoperator cu sondă uretrală pentru 8-12 zile. În al 2-lea lot (36 copii) au fost pacienţi cu hipospadias de diferite localizări (vârsta 12-18 ani). Derivarea urinei s-a efectuat prin epicistostomie suprapubiană troacară sau deschisă şi prin stent uretral de 3-4 cm. Rezultate. Rezultate satisfăcătoare am înregistrat în primul lot la 58 de bolnavi, în al doilea lot - la 30 de pacienţi, la 16 bolnavi din ambele loturi s-au dezvoltat fistule uretrale şi la doi - stenoză meatală. Fistulele uretrocutane au fost înlăturate prin suturarea ţesuturilor adiacente cu ajutorul tehnicii de mărire la 6 luni de la tratamentul chirurgical al hipospadiasului, stenoza meatală a fost rezolvată prin meatoplasie. Concluzii. Utilizarea stentului a contribuit la prevenirea dezvoltării uretritelor şi a cistitelor postoperatorii, cistalgiilor, disconfortului din bazinul mic. Copiii cu stent uretral au fost activi şi nu au acuzat dureri deja de la a 2-a -3-a zi. În rezultatul metodei aplicate, a fost diminuat esenţial numărul de complicaţii, inclusiv cu 50% numărul de stenoze ale orificiului uretral extern şi cu 25% formarea de fistule uretrale, preponderent la pacienţii mai mari de 12-13 ani şi la adolescenţi

Soft Gluon Resummation for Heavy Quark Electroproduction

We present the threshold resummation for the cross section for electroproduction of heavy quarks. We work to next-to-leading logarithmic accuracy, and in single-particle inclusive kinematics. We provide next-to-leading and next-to-next-to-leading order expansions of our resummed formula, and examine numerically the quality of these finite order approximations. For the case of charm we study their impact on the structure function $F_2$ and its differential distribution with respect to the charm transverse momentum.Comment: 27 pages, 17 figure

Peste des petits ruminants virus transmission scaling and husbandry practices that contribute to increased transmission risk: an investigation among sheep, goats, and cattle in Northern Tanzania

Peste des petits ruminants virus (PPRV) causes an infectious disease of high morbidity and mortality among sheep and goats which impacts millions of livestock keepers globally. PPRV transmission risk varies by production system, but a deeper understanding of how transmission scales in these systems and which husbandry practices impact risk is needed. To investigate transmission scaling and husbandry practice-associated risk, this study combined 395 household questionnaires with over 7115 cross-sectional serosurvey samples collected in Tanzania among agropastoral and pastoral households managing sheep, goats, or cattle (most managed all three, n = 284, 71.9%). Although self-reported compound-level herd size was significantly larger in pastoral than agropastoral households, the data show no evidence that household herd force of infection (FOI, per capita infection rate of susceptible hosts) increased with herd size. Seroprevalence and FOI patterns observed at the sub-village level showed significant spatial variation in FOI. Univariate analyses showed that household herd FOI was significantly higher when households reported seasonal grazing camp attendance, cattle or goat introduction to the compound, death, sale, or giving away of animals in the past 12 months, when cattle were grazed separately from sheep and goats, and when the household also managed dogs or donkeys. Multivariable analyses revealed that species, production system type, and goat or sheep introduction or seasonal grazing camp attendance, cattle or goat death or sales, or goats given away in the past 12 months significantly increased odds of seroconversion, whereas managing pigs or cattle attending seasonal grazing camps had significantly lower odds of seroconversion. Further research should investigate specific husbandry practices across production systems in other countries and in systems that include additional atypical host species to broaden understanding of PPRV transmission

Heavy Flavours at Colliders

I review some topics in the production and decays of heavy flavours that are relevant for collider physics. In particular, I discuss the present status and some recent progress related to masses, parton densities and fragmentation functions of heavy quarks, as well as threshold resummation, polarized onium production at high transverse momentum, and a factorization theorem for $B \to\pi\pi$ decays.Comment: 12 pages. Plenary talk given at UK Phenomenology Workshop on Collider Physics, Durham, England, 19-24 Sep 1999 Comments and references adde

b-Initiated processes at the LHC: a reappraisal

Several key processes at the LHC in the standard model and beyond that involve $b$ quarks, such as single-top, Higgs, and weak vector boson associated production, can be described in QCD either in a 4-flavor or 5-flavor scheme. In the former, $b$ quarks appear only in the final state and are typically considered massive. In 5-flavor schemes, calculations include $b$ quarks in the initial state, are simpler and allow the resummation of possibly large initial state logarithms of the type $\log \frac{{\cal Q}^2}{m_b^2}$ into the $b$ parton distribution function (PDF), ${\cal Q}$ being the typical scale of the hard process. In this work we critically reconsider the rationale for using 5-flavor improved schemes at the LHC. Our motivation stems from the observation that the effects of initial state logs are rarely very large in hadron collisions: 4-flavor computations are pertubatively well behaved and a substantial agreement between predictions in the two schemes is found. We identify two distinct reasons that explain this behaviour, i.e., the resummation of the initial state logarithms into the $b$-PDF is relevant only at large Bjorken $x$ and the possibly large ratios ${\cal Q}^2/m_b^2$'s are always accompanied by universal phase space suppression factors. Our study paves the way to using both schemes for the same process so to exploit their complementary advantages for different observables, such as employing a 5-flavor scheme to accurately predict the total cross section at NNLO and the corresponding 4-flavor computation at NLO for fully exclusive studies.Comment: Fixed typo in Eq. (A.10) and few typos in Eq. (C.2) and (C.3

A New 5-Flavour LO Analysis and Parametrization of Parton Distributions in the Real Photon

New, radiatively generated, LO quark (u,d,s,c,b) and gluon densities in a real, unpolarized photon are presented. We perform a global 3-parameter fit, based on LO DGLAP evolution equations, to all available data for the structure function F2^gamma(x,Q^2). We adopt a new theoretical approach called ACOT(chi), originally introduced for the proton, to deal with the heavy-quark thresholds. This defines our basic model (CJKL model), which gives a very good description of the experimental data on F2^gamma(x,Q^2), for both Q^2 and x dependences. For comparison we perform a standard fit using the Fixed Flavour-Number Scheme (FFNS_CJKL model), updated with respect to the previous fits of this type. We show the superiority of the CJKL fit over the FFNS_CJKL one and other LO fits to the F2^gamma(x,Q^2) data. The CJKL model gives also the best description of the LEP data on the Q^2 dependence of the F2^gamma, averaged over various x-regions, and the F_2,c^gamma, which were not used directly in the fit. Finally, a simple analytic parametrization of the resulting parton densities obtained with the CJKL model is given.Comment: 43 pages, RevTeX4 using axodraw style, 3 tex and 12 postscript figures, version submitted to Phys. Rev. D, small text changes, one reference added, FORTRAN program available at http://www.fuw.edu.pl/~pjank/param.html and at http://www-zeuthen.desy.de/~alorca/id4.htm

Single-top production at future ep colliders

The production of top quarks in single mode at future ep colliders is studied, the attention being mainly focused to the case of the proposed LEPXLHC collider. We are motivated to reanalyse such a process following the discovery of the top quark at Fermilab. Thanks to the measurement of its mass one is now able to establish more accurately the relevance of single top production for itself and for many other processes to which it may act as a background. In addition, the recent improvement of our knowledge of the quark and gluon dynamics inside the proton now allows one to pin down the dependence of single top production on the partonic structure functions. Both the leptonic and hadronic decay channels of the top quark are studied and compared to the yield of the corresponding irreducible background in presence of b-taggingComment: 28 pages, latex, epsfig, 10 postscript figures, complete paper available at ftp://axpa.hep.phy.cam.ac.uk/moretti/cavendish_9704 and at http://www.hep.phy.cam.ac.uk/theory/papers