The asymmetry of antimatter in the proton.

The fundamental building blocks of the proton-quarks and gluons-have been known for decades. However, we still have an incomplete theoretical and experimental understanding of how these particles and their dynamics give rise to the quantum bound state of the proton and its physical properties, such as its spin1. The two up quarks and the single down quark that comprise the proton in the simplest picture account only for a few per cent of the proton mass, the bulk of which is in the form of quark kinetic and potential energy and gluon energy from the strong force2. An essential feature of this force, as described by quantum chromodynamics, is its ability to create matter-antimatter quark pairs inside the proton that exist only for a very short time. Their fleeting existence makes the antimatter quarks within protons difficult to study, but their existence is discernible in reactions in which a matter-antimatter quark pair annihilates. In this picture of quark-antiquark creation by the strong force, the probability distributions as a function of momentum for the presence of up and down antimatter quarks should be nearly identical, given that their masses are very similar and small compared to the mass of the proton3. Here we provide evidence from muon pair production measurements that these distributions are considerably different, with more abundant down antimatter quarks than up antimatter quarks over a wide range of momenta. These results are expected to revive interest in several proposed mechanisms for the origin of this antimatter asymmetry in the proton that had been disfavoured by previous results4, and point to future measurements that can distinguish between these mechanisms.

Search for exotic baryons in 800 GeV pp-->pXi+/-piX reactions.

We report the results of a high-statistics, sensitive search for narrow baryon resonances decaying to Xi-pi-, Xi-pi+, Xi+pi-, and Xi+pi+. The only resonances observed are the well known Xi0(1530) and Xi0(1530). No evidence is found for the states near 1862 MeV, previously reported by NA49 [Phys. Rev. Lett. 92, 042003 (2003)]. At the 95% confidence level, we find the upper limit for the production of a Gaussian enhancement with sigma=7.6 MeV in the Xi-pi- effective mass spectrum to be 0.3% of the number of observed Xi0(1530)-->Xi-pi+. We find similarly restrictive upper limits for an enhancement at 1862 MeV in the Xi-pi+, Xi+pi-, and Xi+pi+ mass spectra.

Lambda(0) polarization in 800-GeV/cpp --> p(f)(Lambda0K+).

We report results from a study of Lambda(0) polarization in the exclusive reaction pp --> p(f)(Lambda0K+) at 800-GeV/c. We observe a dependence of the polarization on the Lambda0K+ invariant mass with large (+71%) positive polarization at small mass (1.63-GeV/c(2)) and large (-43%) negative polarization at large mass (2.75-GeV/c(2)). This observation confirms the result of the CERN ISR R608 experiment and extends the range over which the effect is observed. The strong dependence of the polarization on the Lambda0K+ invariant mass suggests that the origin of the polarization is closely related to the production dynamics of the diffractively produced Lambda0K+ system.

Diffractively produced charm final states in 800-GeV/c pp collisions.

We report the first observation of diffractively produced open charm in 800-GeV/c pp collisions of the type pp-->pD*X. We measure cross sections of sigma(diff)(D*+) = (0.185+/-0.044+/-0.054) (mu)b and sigma(diff)(D(*-)) = (0.174+/-0.034+/-0.029) (mu)b. Our measurements are based on 4.3x10(9) events recorded by FNAL E690 in the fixed-target run of 1991. We compare our results with previous fixed-target charm experiments.

Achados laparoscópicos na infertilidade / Infertility and laparoscopic finding

O objetivo deste trabalho é rever retropectivamente os achados laparoscópicos em mulheres infertéis. Entre 1990 e 1997 foram realizadas 115 laparoscopias em mulheres com queixa de infertilidade, seguidas no ambulatório de Esterelidade da Faculdade de Medicina de Londrina/UEL. Deste total, 100 mulheres foram analisadas quanto a idade, paridade, tipos de partos e abortos anteriores, presença de prenhez ectópica anteiror ao procedimento laparóscopico, história prévia de doença inflamatória pélvica (DIP) e dismenorréia. A seguir as pacientes foram avaliadas quanto ao achado laparoscópio, sendo os mais freqüentes endometriose (54 por cento) e aderências pélvicas (49 por cento). Ainda foram encontradas 22 pacientes com laqueadura tubária prévia e nove pacientes com mioma. Deste universo de pacientes 39 tiveram cromotubagens positivas, 34 cromotubagens negativas, 20 cromotubagens positiva uniteralmente e sete inconclusivas

Sindrome de transfusäo feto-fetal / Twin-to-twin transfusion syndrome

Os autores realizaram uma revisÝo bibliográfica abragendo conceitos atuais sobre definiçÝo, fisiopatologia, diagnóstico, seguimento, tratamento e complicaçSes na Sindrome de transfusÝo feto-fetal. Eles confrontam as várias polêmicas sobre a eficácia e benefícios dos modernos métodos de diagnóstico e sua contribuiçÝo nos resultados neonatais