Search PubMed⌕ Search

Biomedical subjects

A Bischoff

Publications and source records attributed to A Bischoff.

At least 19 recordsLinked to original sources
PubMed2005

Measurement of dijet azimuthal decorrelations at central rapidities in pp collisions at sqrt s =1.96 TeV.

Correlations in the azimuthal angle between the two largest transverse momentum jets have been measured using the D0 detector in p (-)p collisions at a center-of-mass energy sqrt[s]=1.96 TeV. The analysis is based on an inclusive dijet event sample in the central rapidity region corresponding to an integrated luminosity of 150 pb(-1). Azimuthal correlations are stronger at larger transverse momenta. These are well described in perturbative QCD at next-to-leading order in the strong coupling constant, except at large azimuthal differences where contributions with low transverse momentum are significant.

Journal Article↗
PubMed2005

Measurement of the B0s lifetime in the exclusive decay channel B0s-->J/psiphi.

Using the exclusive decay B0s-->J/psi(mu+mu-)phi(K+K-), we report the most precise single measurement of the B0s lifetime. The data sample corresponds to an integrated luminosity of approximately 220 pb(-1) collected with the D0 detector at the Fermilab Tevatron Collider in 2002-2004. We reconstruct 337 signal candidates, from which we extract the B0s lifetime, tau(B0s)=1.444(+0.098)(-0.090)(stat)+/-0.020(sys) ps. We also report a measurement for the lifetime of the B0 meson using the exclusive decay B0-->J/psi(mu+mu-)K*0(892)(K+pi-). We reconstruct 1370 signal candidates, obtaining tau(B0)=1.473(+0.052)(-0.050)(stat)+/-0.023(sys) ps, and the ratio of lifetimes, tau(B0s)/tau(B0)=0.980(+0.076)(-0.071)(stat)+/-0.003(sys).

Journal Article↗
PubMed2005

Search for supersymmetry with gauge-mediated breaking in diphoton events at D0.

We report the results of a search for supersymmetry (SUSY) with gauge-mediated breaking in the missing transverse energy distribution of inclusive diphoton events using 263 pb(-1) of data collected by the D0 experiment at the Fermilab Tevatron Collider in 2002-2004. No excess is observed above the background expected from standard model processes, and lower limits on the masses of the lightest neutralino and chargino of about 108 and 195 GeV, respectively, are set at the 95% confidence level. These are the most stringent limits to date for models with gauge-mediated SUSY breaking with a short-lived neutralino as the next-to-lightest SUSY particle.

Journal Article↗
PubMed2004

Observation and properties of the X(3872) decaying to J/psipi(+)pi(-) in pp collisions at sqrt[s]=1.96 TeV.

We report the observation of the X(3872) in the J/psipi(+)pi(-) channel, with J/psi decaying to mu(+)mu(-), in pp collisions at sqrt[s]=1.96 TeV. Using approximately 230 pb(-1) of data collected with the Run II D0 detector, we observe 522+/-100 X(3872) candidates. The mass difference between the X(3872) state and the J/psi is measured to be 774.9+/-3.1(stat)+/-3.0(syst) MeV/c(2). We have investigated the production and decay characteristics of the X(3872) and find them to be similar to those of the psi(2S) state.

Journal Article↗
PubMed2004

Search for doubly charged higgs boson pair production in the decay to mu(+)mu(+)mu(-)mu(-) in pp collisions at sqrt[s]=1.96 TeV.

A search for pair production of doubly charged Higgs bosons in the process pp -->H(++)H(--) -->mu(+)mu(+)mu(-)mu(-) is performed with the D0 run II detector at the Fermilab Tevatron. The analysis is based on a sample of inclusive dimuon data collected at an energy of sqrt[s]=1.96 TeV, corresponding to an integrated luminosity of 113 pb(-1). In the absence of a signal, 95% confidence level mass limits of M(H(+/-+/-)(L))>118.4 GeV/c(2) and M(H(+/-+/-)(R))>98.2 GeV/c(2) are set for left-handed and right-handed doubly charged Higgs bosons, respectively, assuming 100% branching into muon pairs.

Journal Article↗
PubMed2004

Knee arthroplasty for spontaneous osteonecrosis of the knee: unicompartimental vs bicompartimental knee arthroplasty.

Spontaneous osteonecrosis of the knee (SON) is an osteonecrosis that mainly affects the medial femoral condyle. In endstage SON, knee arthroplasty is the therapy of choice. Because of the unicompartimental nature of the knee, unicondylar knee arthroplasty is considered an ideal implant for treatment of this condition. The purpose of this study was to prove that the long-term results of unicondylar implants are better than the results of bicondylar implants for the treatment of SON. All patients treated for SON between 1984 and 2000 have been recorded. Two groups were formed according to the implant used. In all patients the preoperative radiograph was analyzed according to stage and size of the osteonecrotic lesion and the osteoarthritic changes. Postoperatively, the Knee Society Score and the radiograph were recorded. Thirty-nine patients were included in this study, of which 23 patients were treated by a unicondylar implant and 16 by a bicondylar implant. On a short-term basis, unicondylar implants had better clinical results; however, on a long-term basis bicondylar implants were better. In comparison, only unicondylar implants had to be revised. Radiolucency lines were mainly observed in patients with unicondylar impants and large areas of osteonecrosis. Our long-term results suggest that patients with SON are better treated by bicondylar implants. The reasons for the higher failure rate for unicondylar implants are poor bone stock and secondary arthritic changes.

Aged↗
PubMed2004

[Antibodies against vaccine-preventable diseases in pregnant women and their offspring. Diphtheria, pertussis, tetanus].

In the eastern part of Germany, the age of primigravid women has increased from the end of the 2nd decade to the second half of the 3rd decade since 1990. This might influence the vaccine-induced immunity in pregnant women as well as their newborns. The objective of the present study was to examine the influence of the higher age of pregnant women on antibody protection. Maternal and cord blood samples of 290 women in the eastern part of Germany with a mean age of 28 years were analyzed for antibodies against the vaccine-preventable diseases diphtheria, pertussis, and tetanus. Compared with the data on vaccination history, the seroprevalence rate of tetanus was significantly enhanced and the seroprevalence rate of diphtheria and pertussis was significantly reduced. Detectable levels of antibodies against tetanus toxin were found in 93% of the mothers, against diphtheria toxin in 70%, and against Bordetella pertussis in 37%. Cord blood samples had a significantly higher prevalence of antibodies against pertussis and diphtheria in comparison to maternal probes. In addition,there were significantly enhanced antibody concentrations against diphtheria toxin in the newborns. In conclusion, the prevalence of antibodies determined suggests they are insufficient for protecting the newborns efficiently against pertussis and diphtheria in spite of the evidence for an active placental antibody transfer.

Adult↗
PubMed2004

[Antibodies against vaccine-preventable diseases in pregnant women and their offspring. Measles, mumps, rubella, poliomyelitis, and varicella].

In the eastern part of Germany, the age of primigravid women has clearly increased since 1990. This may change the protection provided by antibodies in pregnant women as well as their newborns. The objective of the present study was to assess antibodies against vaccine-preventable viral infectious diseases in pregnant women and their offspring to draw conclusions about their protection. Maternal and cord blood samples of 290 women from the eastern part of Germany with a mean age of 28 years were analyzed for antibodies against measles, mumps, rubella, poliomyelitis, and varicella. The study showed that the pregnant women had detectable levels of antibodies against measles virus in 79%, against mumps virus in 96%, against rubella virus in 87%, against polioviruses types 1-3 in 62-64%, and against varicella-zoster virus (VZV) in 97% of the cases. The seroprevalence of the antibodies in the newborns were not significantly different from those of their mothers. When antibody titers of mothers and newborns were compared, significantly higher titers to VZV could be detected in the cord blood sera of newborns. It is suggested that the prevalence of antibodies against measles and poliomyelitis is insufficient to protect the newborns efficiently. An immunity gap of 13% against rubella in mothers results in a potential risk for a congenital rubella syndrome in newborns. Despite the high seroprevalence of rubella and chickenpox, there is considerable potential for infections during pregnancy and neonatal period.

Antibodies, Viral↗
PubMed2002

Antibodies against vaccine-preventable diseases in pregnant women and their offspring in the eastern part of Germany.

Maternal and cord blood samples of 290 pregnant women in the eastern part of Germany with a mean age of 28 years (16-41 years) were analyzed for antibodies to vaccine-preventable diseases. Both mothers and infants had detectable levels of antibodies to mumps in 96% and to tetanus in 93% of cases. Detectable levels to poliomyelitis, diphtheria, measles and rubella varied from 55% to 91%. Cord blood samples had a significantly higher prevalence of antibodies to pertussis (61%) and diphtheria (81%) in comparison to maternal samples (pertussis 37%, diphtheria 70%) as well as significantly enhanced antibody concentrations to diphtheria. In conclusion, the prevalence of antibodies to pertussis (61%), diphtheria (81 %), poliomyelitis (55-59%) and measles (85%) is suggested to be insufficient in newborn infants to protect them against these infectious diseases.

Adolescent↗