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The Southern Lapwing (Vanellus chilensis) is a typical bird from southern Brazil, but it is widely distributed across South America. It is well-recognized by its characteristic colors, imposing vocalization and aggressive behavior. The species inhabits grasslands, which can vary locally and regionally. The aim of this study is to evaluate how Southern Lapwings select their macro- and micro-habitats, which is necessary to better understand the species’ ecology, its relationship with the environment and the complex interaction between behavior and territory. This research intends to verify if there is any kind of selection for a specific environment and which factors influence the choice of feeding and breeding territories. Fieldwork was carried out at 40 ha in the state of Rio Grande do Sul, with 60 sampling points divided across six different vegetal formations. For macro-habitats, we analyzed data on availability and use of the area through the selection index, while for micro-habitat selection we constructed Generalized Linear Models (GLM) with the measures of environmental variables for each point. The selection index indicates that there is a strong preference for impacted grasslands, while lapwings seem to avoid forests and shrubland during both breeding and non-breeding seasons. The micro-habitat analysis indicates that the birds generally select areas with low vegetation height, and a certain degree of local human impact, but that the presence of farm animals is only preferred during the non-breeding season. This study shows...

In 2007 the International Psoriasis Council proposed that palmoplantar pustulosis (PPP) should be considered a separate condition from psoriasis, despite the presence of certain phenotypes common in both diseases.To describe and compare demographic and clinical characteristics among patients with PPP and palmoplantar plaque psoriasis.This was a retrospective case series study from 2005 to 2010. The following data were obtained: age, sex, family history, smoking habits, nail involvement, joint involvement, disease duration, lesion morphology (plaque or pustular), histological diagnosis, comorbidities, and Physician's Global Assessment (PGA) score for extrapalmoplantar lesions. The sample size calculation indicated that 80 patients, 40 patients for each group (palmoplantar plaque psoriasis and PPP) were needed to see clinically relevant differences between groups.Ninety patients were selected, 51 with palmoplantar plaque psoriasis and 39 with PPP. No statistically significant differences were registered between patients affected by PPP and palmoplantar plaque psoriasis as regards age at onset of the disease (48 vs. 44 years; P=0·4), disease duration (6 vs. 10 years; P=0·1), family history of psoriasis (28% vs. 33%; P=0·7), concomitant arthritis (26% vs. 25%; P=1·0), or smoking habits (54% vs. 41%; P=0·2). We observed a female predominance (P=0·01) and a lesser frequency of nail involvement (P=0·03) in patients affected by PPP.Our data suggest a close relationship between PPP and psoriasis. The existing data concerning epidemiology, clinical presentation, genetics, histopathology and pathogenesis do not permit a clear distinction between these two entities, which seem to coincide in many aspects. PPP appears to have a marked predilection among female smokers.

Blastic plasmacytoid dendritic cell neoplasm (BPDNC) is a rare tumour, which stems from plasmacytoid dendritic cells. Although the aetiology is still unclear, in the last few years various reports suggested a potential role of chromosomal aberrations in the oncogenesis. The disease is currently enclosed among "acute myeloid leukemia (AML) and related precursor neoplasms" in the last WHO classification. BPDCN has an aggressive course, however, it has been suggested that an exclusive cutaneous involvement at presentation is related to a better clinical outcome.We review the literature about BPDCN, and we present a series of 11 cases, all characterised by disease limited to the skin at presentation. Furthermore, we examined all cases of the last 10 years stored in the database of the multidisciplinary study group on cutaneous lymphomas of the University of Florence.Basing on the clinical features, patient were classified into two groups: with a single-lesion or multiple eruptive-lesions presentation. The former were treated with radiotherapy (limited field, electron beam therapy). The latter were treated with different therapeutic options, depending on age and co-morbidities. All patients with a single lesion achieved complete response. Five of 6 patients with eruptive lesions achieved a clinical response (2 complete and 3 partial response). Notably, the progression free survival was higher in the single-lesion than in the eruptive-lesion group (23 vs. 9 months). However all patients relapsed and 8 of 11 died.Although the small number of selected patients, we could speculate that the concept of "cutaneous sanctuary" is particularly true in patients with a single lesion-presentation. In these patients, especially if70 year-old aged, radiotherapy should be encouraged as the treatment of choice.

Among primary cutaneous B-cell lymphomas (CBCL), two main clinico-pathologic entities are recognized, i.e. marginal zone lymphoma (MZL), otherwise defined as extranodal MZL, MALT (Mucosa-Associated Lymphoid Tissue) type, and follicle center lymphoma (FCL). They are mostly characterized by indolent course (very limited risk of extracutaneous spread), very good response to non-aggressive treatment (radiotherapy is the gold standard), and excellent prognosis (90% 5-year survival overall). The clinical presentation of MZL and FCL slightly differ concerning site predilection (trunk and upper limbs in the former, headneck and trunk in the latter) and frequency of cases with multiple, non-contiguous lesions (higher in MZL). Histologically, MZL and FCL share the multiphasic evolution of lesions, while some distinctive features are clues to diagnosis and differential diagnosis: CD5-/CD10-/bcl2+ phenotype of neoplastic cells, "colonization" of reactive lymphoid follicles by neoplastic cells, lymphoplasmacytoid and plasma cells at the periphery of nodular infiltrates in MZL; CD5-, CD10 +/-, bcl6+, MUM-1 neg, FOX-P1 neg, IRF4 neg, IgM neg phenotype of neoplastic cells (centrocytes), and neoplastic follicles (in early lesions) in FCL.

Adrenomedullin (AM) is a multifunctional regulatory peptide with important angiogenic and mitogenic properties. Here we identify a region of stable secondary structure in the 5'-untranslated region (5' UTR) of human AM mRNA. Reverse transcriptase-polymerase chain reaction of the 5' UTR consistently resulted, in addition to the product with the expected size of 155 base pair (bp), in a second product with an approximately 65-bp deletion from the central region of the 5' UTR, suggesting the presence of a secondary structure. The presence of a stem-loop structure was confirmed by probing the 5' UTR with RNases with selectivity for single- or double-stranded RNA. We investigated the role of this stem-loop structure in expression of luciferase reporter gene in cultured cell lines. Reporter assays using a chimeric mRNA that combined luciferase and the 5' UTR of AM mRNA demonstrated a dramatic decrease of the reporter activity owing to a decreased translation, whereas the deletion of the stem-loop structure localized between nt +31 and +95 from the cap site led to the recovery of activity. Gel migration shift assays using cytosolic extracts from mammalian cell lines demonstrate a specific binding of a cytosolic protein to riboprobes containing the 5' UTR of AM but not to riboprobes either corresponding to other areas of the message or containing the 5' UTR but lacking the region of secondary structure. Although we conclude that the 5' UTR of the human AM mRNA can modulate the translation of AM mRNA in vivo, and that the predicted stem-loop structure is necessary for this inhibition, the functional consequences of the cis element-binding activity remain to be determined.

After castration or therapeutic hormone deprivation, most cancer of the prostate (CaP) cells develop androgen-independent (AI) growth. In this work, we studied the effect of androgen depletion (castration) on the growth of experimental model LuCaP 23.1 xenograft. A total of 101 nude mice were implanted and analysed for their growth profile before experimental period 1 (11 weeks) and after castration experimental period 2 (15 weeks). For specific periods, tumors were harvested and assessed for molecular marker expression specific for CaP. Taking into account tumor dynamic growth, prior to castration we found 37 fast growing (FG) tumors (948.9 ± 76.9 mm 3 ) and 63 slow growing (SG) tumors (229.6 ± 18.4 mm 3 ). Real-time quantitative RT-PCR showed that in comparison to SGs, FGs contained elevated expression of epidermal growth factor receptor type 1 (HER1), urokinase plasminogen activator (uPA), thymidine phosphorylase (TP) and thymidilate synthase (TS) mRNAs expression and low levels of 5α-reductase 2 (5α-R2) mRNA. After castration all FG tumors progressed rapidly (by 5 weeks) to AI growth (FG-P). In SG castrated tumors, 66% of tumors showed retarded progression (by 12 weeks) to AI (SG-P), whereas 34% responded to castration (SG-R). Molecular analysis demonstrated distinct molecular profiles integrating different pathways associated with AI progression. The progressive tumors FG-P, and some tumors of SG-P subgroup, presented significantly high levels of HER1, epidermal growth factor receptor type 2 (HER2), TS, uPA, TP, tumor necrosis factor superfamily member 6 (FAS) and peptidylglycine α-amidating mono-oxygenase (PAM) mRNA all of which correlated with androgen receptor (AR) mRNA. The second subgroup of SG-P tumors showed a high expression of the anti-apoptotic gene Bcl-2. A third subgroup of SG-P tumors showed significant expression of hypoxia-related genes such as adrenomedullin (AM) after castration. LuCaP 23.1 xenograft represent a useful dynamic model to study pre-clinically new therapeutic molecules and evaluate non-randomized therapeutics protocols combining different target inhibition specific to each AI pathways.

Correspondence: Nicola Pimpinelli, MD, PhD Dept. Surgery and Translational Medicine Division Dermatology University of Florence Medical School Viale Michelangiolo, 41 50125 Florence, Italy E mail: nicola.pimpinelli@unifi.it SUMMARY Brentuximab vedotin (BV) is an anti-CD30 monoclonal antibody conjugated with the cytotoxic drug monomethylyauristatin E (MMAE), a potent microtubule inhibitor. In relapsed/refractory Hodgkin lymphoma and systemic anaplastic large cell lymphoma, BV achieved durable response with low and transitory toxicity. Accordingly, it was approved by FDA in 2011 for patients affected by these malignancies. In some case reports, BV obtained rapid response in CD30-expressing cutaneous T-cell lymphoma, as transformed mycosis fungoides and relapsed/refractory primary cutaneous ACL lymphoma. Currently, two phase 2 trials are ongoing to assess the potential use of brentuximab in patients affected by refractory/relapsed CD30+ T-cell lymphoproliferative disorders and in patients affected by mycosis fungoides/Sezary syndrome, respectively. Finally, one phase 3 trial is comparing brentuximab to methotrexate or bexarotene in CD30-expressing cutaneous T-cell lymphomas. Among the several new drugs tested in the last 5 years, BV showed the most promising and challenging results to be translated in the clinical practice. Brentuximab vedotin in CD30-expressing cutaneous T-cell lymphoma

The escalating role played by managed care organizations in the health-care system is reflected in the increased demand for cost-effectiveness analyses (CEAs) to assess the balance between economic impact and clinical efficacy. For example, the high incidence and costs associated with colorectal cancer in Latin America calls for a comprehensive economic evaluation to ensure appropriate allocation of limited health-care funds. In addition, the current call for a "societal" perspective of such analyses indicates the need for increased consideration of the concerns of both patient and health-care provider. The introduction of oral tegafur and uracil (UFT) provided the opportunity to evaluate the pharmacoeconomic advantage of the new agent compared with the standard fluorouracil (5-FU). Results of this study indicated an economic advantage for oral UFT vs a 5-FU-based regimen in the treatment of colorectal cancer in Brazil and Argentina. It was further noted that the mild toxicity profile of UFT reduced both the number of clinic visits and the need for venipuncture procedures. Noting that oral UFT may have a positive impact on quality of life in addition to its estimated economic benefit, it was concluded that prospective economic research and quality-of-life evaluations are needed to fully assess the pharmacoeconomic impact of oral UFT.

The treatment of colorectal cancer continues to pose major challenges for oncologists throughout the world. Uracil and tegafur (UFT), as an oral agent, represents a new patient-focused approach to managing a malignancy with few treatment alternatives other than an intravenous fluorouracil (5-FU)-based regimen. The ability of UFT to achieve equivalent clinical outcomes compared with continuous 5-FU infusion, along with its oral formulation and mild toxicity profile, provide a compelling backdrop for fiscal analysis. An economic assessment of therapy attributes and effects would, therefore, be prudent and necessary when deliberating the adoption of this chemotherapy regimen. We developed a pharmacoeconomic model in Brazil and Argentina identifying clinical practices associated with chemotherapy administration and adverse event management practices from a panel of physicians assembled in each country. Practice patterns and clinical events were then evaluated for resource utilisation trends. The perspective of this pharmacoeconomic analysis was that of the healthcare payor. Country-specific charge data were applied to the identified resources to arrive at an average cost per patient receiving a 6-cycle course of 5-FU with either levamisole and/or leucovorin as a modulator vs a modelled oral UFT/leucovorin regimen. As a comparator, the oral UFT/leucovorin regimen was modelled based on the expert panel's input. Adverse events and incidence data were derived from clinical trial data for both agents. Both agents were analysed in the treatment of metastatic disease and as adjuvant therapy. The principal findings of a cost-minimisation analysis in Brazil revealed approximately equivalent treatment costs for both regimens in the adjuvant setting. When analysing the metastatic treatment arm, costs diverged by $R335/per patient ($R = Reals - the currency of Brazil) in favour of a UFT regimen. The profile in Argentina yielded more dramatic differences, with a UFT regimen costing $P782/per patient ($P = Pesos - the currency of Argentina) less than a 5-FU regimen in the adjuvant setting. In the treatment of metastatic disease, a UFT regimen provided $P1188/per patient in savings over a 5-FU regimen. These differences are predominantly driven by the mild toxicity profile of UFT and its corresponding less severe adverse event management practice patterns. In addition, the oral formulation of UFT versus intravenous 5-FU provides for ease of administration, lowering the total cost of care as well as likely impacting on the patient's quality of life. The pharmacoeconomic results suggest that a UFT regimen is a useful and economical alternative to the standard 5-FU regimen in the treatment of colorectal cancer in Brazil and Argentina.

e22214 Background: Triple negative breast cancer (BC) is a distinct group of tumors that show common but heterogeneous morphologic, genetic, and immunophenotypic features. Despite differences in the definition and prevalence, it comprises 8% to 20% of all breast cancers and is associated with an aggressive clinical course with significant risk of either local or systemic relapse and subsequent increased risk of death on short term follow up (particularly in the first 5 years).We study the pathological characteristics and the clinical outcome of a cohort of 77 triple negative BC patients (pts) diagnosed at our Institution. Methods: Between January 1999 and September 2008, 77 (stage I to III) triple negative BC pts. were retrospectively analyzed. All pts had their receptor status, Her neu, ck-5, ck-6 and staining for EGFR by the same pathologist. Pathological parameters (Pp) analyzed were: status of axilary lymph nodes (LN), nuclear grade, histologic grade, mitotic index and vascular invasion and the use of antraciclins in the adjuvant setting. Univariate and multivariate analysis (proporcional hazard regression Cox model) for the Pp associated with relapse, and the log rank test to compare two curves of each Pp for disease free survival (DFS), and overall survival (OS) were performed. Results: The median age was 57.8 years (range 30–86 years).The median follow up time was 57.7 months (range, 4- 241). From 77 Pts. analized, 65 (84.4%) were basal-like and 43 (64.6%) of those were GH3. Stage at the time of presentation was: 16 (20,7%) stage I; 40 (51,9%) stage II; 21 (27,7%) stage III. Pre-menopausal status was 29,48% (23 pts.), and 61% (47 pts) were LN negative. Overall, relapse rate was 38.5 % (n= 30), 63 Pts (81.8%) are still alive. Median DFS was not reached. Global DFS and OS were 59% and 79% respectively, and status of LN was the only prognostic factor. LN- vs LN+ DFS (p< 00.02) and OS p (< 0.02).All others Pp analyzed were not statistically significative. Conclusions: Despite previous studies have demonstrated that triple negative is an independent marker of poor prognosis in BC as a whole, in the LN-negative, and LN-positive groups, in this basal like population only positive LN was an independent poor prognostic factor for DFS and OS. No significant financial relationships to disclose.

We review various incisions for treatment of tumors of the face and parotid and submaxillary regions, as well as for radical neck surgery. A contribution to this field is made in the form of facial and cervical incisions that not only provide broad exposure of the region affected by the tumor, but also involve incision traces based on plastic surgery criteria. In this respect, we describe plastic modeling of the facial, submaxillary, and neck contours, resorting to the sternocleidomastoid and trapezius muscles.

From three-prong decays of tau leptons produced in the MAC detector at PEP, the lifetime of the tau is determined to be (4.9 +- 2.0) x 10/sup -13/ sec.

We have studied the production of acollinear muon pairs in e/sup +/e/sup -/ interactions using the MAC detector at PEP. The results are totally accounted for by the QED processes e/sup +/e/sup -/..-->..e/sup +/e/sup -/..mu../sup +/..mu../sup -/ and e/sup +/e/sup -/..--> mu../sup +/..mu../sup -/..gamma.. in which only the muon pairs are detected. We have also searched for the production of the supersymmetric partners of the muon. The existence of a spin-0 supersymmetric partner of the muon with a mass

We describe a combined procedure of mobilization of the orbitofrontal flap, which involves passing through a subgaleal plane in the posterior region, corresponding to a portion of the scalp, and subcutaneously in the anterior frontal and orbital region. The galea, in the shape of an albatross wing, is irrigated via the distal parts of the temporal vessels. The flap lies free of the frontal muscle and the suprazygomatic aponeurotic sheath, thus allowing a broad shifting space for the replacement of each part in a manner that is both anatomically and artistically satisfactory. This technique avoids lesions of the frontal and orbicularis branches as well as alopecia, both the surgical kind and that caused by traction.

We report a high-precision measurement of the ratio R of the total cross section for e/sup +/e/sup -/..-->..hadrons to that for e/sup +/e/sup -/..--> mu../sup +/..mu../sup -/, at a center-of-mass energy of 29.0 GeV using the MAC detector. The result is R = 3.96 +- 0.09. This value of R is used to determine a value of the strong coupling constant ..cap alpha../sub s/ of 0.23 +- 0.06, nearly independent of fragmentation models. Two different analysis methods having quite different event-selection criteria have been used and the results are in agreement. Particular attention has been given to the study of systematic errors. New higher-order QED calculations are used for the luminosity determination and the acceptance for hadrons.

The reactions e/sup +/e/sup -/..--> mu../sup +/..mu../sup -/..gamma gamma.. and e/sup +/e/sup -/..--> mu../sup +/..mu../sup -/..gamma.. have been studied at ..sqrt..s = 29 GeV with the MAC detector at the SLAC storage ring. The measured cross sections, charge asymmetry, and invariant-mass distributions are in good agreement with the predictions of QED theory. Limits are derived for the production of excited muon states.

A measurement of the cross section for production of collinear muon pairs based upon a sample of about 3000 events observed in the MAC detector at the storage ring PEP is presented. From the angular asymmetry A/sub mumu/ = -0.076 +- 0.018 the axial vector weak neutral coupling is found to be given by g/sub A//sup e/g/sub A//sup ..mu../ = 0.31 +- 0.08. .AE

Final results are presented from a search for single-photons produced in association with neutrinos or other weakly interacting neutral particles in e/sup +/e/sup -/ annihilations at ..sqrt..s = 29 GeV. The search was performed with the MAC detector at PEP in a total integrated luminosity of 177 pb/sup -1/. The search limits the number of light-neutrino families to N/sub nu/ 50 GeV/c/sup 2/ if m/sub e tilde L/ = m/sub e tilde R/ and m/sub ..gamma.. tilde/ = 0. The mass of the wino is limited to m/sub W tilde/ > 51 GeV/c/sup 2/ if m/sub nu tilde/ = 0. These limits are at the 90% confidence level.

The energy-energy correlation cross section for hadrons produced in electron-positron annihilation at a center-of-mass energy of 29 GeV has been measured with the MAC detector at SLAC. The result is corrected for the effects of detector resolution, acceptance, and initial-state radiation. The correlation is measured in two independent ways on the same data sample: the energy weights and angles are obtained either from the energy flow in the finely segmented total absorption calorimeters or from the momenta of charged tracks in the central drift chamber. This procedure helps reduce systematic errors by cross-checking the effects of the detector on the measurement, particularly important because the corrections depend on complex Monte Carlo simulations. The results are compared with the predictions of Monte Carlo models of complete second-order perturbative quantum chromodynamics and fragmentation, with the following conclusions: (1) fitting the asymmetry for large correlation angles gives values for ..cap alpha../sub S/ of 0.120 +- 0.006 in perturbation theory, 0.185 +- 0.013 in the Lund string model, and values which vary from 0.105 to 0.140 ( +- 0.01) in the incoherent jet models, depending on the gluon fragmentation scheme and the algorithm used for momentum conservation; and (2) the string fragmentation model providesmore » a satisfactory description of the measured energy-energy correlation cross section, whereas incoherent jet formation does not.« less

From a sample of hadronic events, produced in e/sup +/e/sup -/ collisions, semileptonic decays of heavy particles have been isolated and used to obtain a measurement for the bottom-quark lifetime of (1.8 +- 0.6(stat.) +- 0.4(syst.)) x 10/sup -12/ sec.

A study of the lateral development of jets of hadrons produced in electron-positron annihilation has been used to determine the strong coupling constant {alpha}{sub {ital s}}. Data were obtained with the MAC detector at the SLAC {ital e}{sup +}e{sup {minus}} storage ring PEP at {radical}{ital s} =29 GeV. Based on the parton calculations of Gottschalk and Shatz, a value for {alpha}{sub {ital s}} of 0.133{plus minus}0.005(stat){plus minus}0.009(syst) has been determined for string fragmentation, and 0.112{plus minus}0.008(stat){plus minus}0.007(syst) for an independent-jet model.

The rate of like-charge dimuons has been measured with the MAC detector in hardonic events produced in e + e − annihilation at √ s =29 GeV. If the observed excess is attributed to B 0 B 0 mixing, the corresponding value of the mixing parameter χ = Γ (B→ μ − X)/ Γ (B→ μ ± X) is χ =0.21 +0.29 −0.15 and χ >0.02 at 90% CL.

A search for supersymmetric electron production via the reaction ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{e}^{\ifmmode\pm\else\textpm\fi{}}\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{\ensuremath{\gamma}}{\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{e}}^{\ensuremath{\mp}}$ followed by the decay ${\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{e}}^{\ensuremath{\mp}}\ensuremath{\rightarrow}{e}^{\ensuremath{\mp}}\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{\ensuremath{\gamma}}$ has been performed with the MAC detector at the electron-positron storage ring PEP. No candidates were found in a sample corresponding to an integrated luminosity of 36.4 ${\mathrm{pb}}^{\ensuremath{-}1}$. For a massless $\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{\ensuremath{\gamma}}$ this corresponds to a lower limit on the $\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{e}$ mass of 22.4 GeV/${\mathit{c}}^{2}$ at the 95% confidence level.

High p ⊥ inclusive muon events produced in e + e − annihilations at √ s =29 GeV have been analyzed to obtain a measurement of the b b forward-backward charge asymmetry. The result A b =0.034±0.070±0.035 differs from the theoretical expectation (−0.16) unless substantial B 0  B 0 mixing is assumed.

Direct photon production in hadronic events from e/sup +/e/sup -/ annihilation has been studied at ..sqrt..s = 29 GeV with use of the MAC detector at the PEP storage ring. A charge asymmetry A = (-12.3 +- 3.5)% is observed in the final-state jets. The cross section and the charge asymmetry are in good agreement with the predictions of the fractionally charged quark-parton model. Both the charge asymmetry and total yield have been used to determine values of quark charges. Limits have been established for anomalous sources of direct photons.

The MAC detector at PEP recorded data for an integrated luminosity of 335 pb −1 between 1980 and 1986. The design of this low-cost MA gnetic C alorimeter was optimized for electron and muon identification, as well as for the measurement of hadronic energy flow. Muon identification is available over 96% of the solid angle, and MAC was the first detector to make large-scale use of gas-sampling calorimetry. Electromagnetic calorimetry in the central section employs alternating layers of lead and proportional wire chambers (PWCs), and hadron and the remaining electromagnetic calorimetry is accomplished with iron plate and PWC layers. A relatively small central drift chamber in an axial magnetic field provides pattern recognition and modest momentum determination. An outer blanket of drift tubes completes the muon identification system. During the latter two years of operation an innovative “soda straw” vertex chamber made more precise lifetime measurements possible. With an evolving trigger system and highly automated data acquisition system, this modest detector has exceeded most of its designers' expectations and has produced a gratifying spectrum of physics results.

Precise results are reported for the $\ensuremath{\tau}$-lepton lifetime and several $\ensuremath{\tau}$ branching ratios obtained with the MAC detector operating at PEP at $\sqrt{s}=29$ GeV. We find ${\ensuremath{\tau}}_{\ensuremath{\tau}}=(3.15\ifmmode\pm\else\textpm\fi{}0.36\ifmmode\pm\else\textpm\fi{}0.4)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}13}$ sec. Results for the topological branching ratios ${B}_{1}$, ${B}_{3}$, ${B}_{5}$ ($\ensuremath{\tau}$ decaying into 1, 3, 5 charged particles) are ${B}_{3}\ensuremath{\equiv}1\ensuremath{-}{B}_{1}=0.133\ifmmode\pm\else\textpm\fi{}0.003\ifmmode\pm\else\textpm\fi{}0.006$ and ${B}_{5}l0.0017$ at the 95% confidence level. The fraction of all three-prong decays unaccompanied by ${\ensuremath{\pi}}^{0}'\mathrm{s}$ is found to be 0.61\ifmmode\pm\else\textpm\fi{}0.03\ifmmode\pm\else\textpm\fi{}0.05.

A search for single electrons produced by the decay of singly produced supersymmetric electrons (e-italic-tilde) or W's (W-italic-tilde) within the MAC detector at the SLAC storage ring PEP has been performed in e/sup +/e/sup -/ annihilations at ..sqrt..s = 29 GeV. No evidence of supersymmetric-particle production is observed in a data sample with an integrated luminosity of 206 pb/sup -1/. Limits on possible masses of supersymmetric electrons and photons (gamma-tilde) are presented. The e-italic-tilde mass limit is m/sub e-italic-tilde/>24.5 GeV/c/sup 2/ at the 90% confidence level if m/sub e-italic-tilde//sub >//sub L//sub =/ = m/sub e-tilde//sub =/ and m/sub gamma-tilde/ = 0. If m/sub e-italic-tilde//sub >//sub L//sub =/>>m/sub e-tilde//sub =/, the corresponding limit is m/sub e-italic-tilde//sub >//sub R//sub =/>23.3 GeV/c/sup 2/. Limits on possible masses of supersymmetric W's and neutrino's (nu-tilde) are also presented. The W-italic-tilde mass limit is m/sub W-italic-tilde/>22.0 GeV/c/sup 2/ at the 90% confidence level if m/sub nu-tilde/ = 0.

A high-precision measurement of the differential cross section for Bhabha scattering (e/sup +/e/sup -/..-->..e/sup +/e/sup -/) is presented. The measurement was performed with the MAC detector at the PEP storage ring of the Stanford Linear Accelerator Center, at a center-of-mass energy of 29 GeV. Effects due to electroweak interference are observed and agree well with the predictions of the Glashow-Salam-Weinberg model. The agreement between the data and the electroweak prediction rules out substructure of the electron up to mass scales of 1 TeV.

The design considerations, construction techniques, prototype tests and performance characteristics of a pressurized drift chamber used in the MAC detector at PEP are described. The chamber consists of 324 aluminized mylar tubes of 6.9 mm diameter with wall thickness of 100 μm. With appropriate shielding it operates successfully at 4.6 cm from the beam line. It was simple to construct and was configured to permit any malfunctioning tubes to be remotely disconnected without affecting operation. The chamber operated without problems for two years in the PEP environment with a gas mixture of 49.5% argon, 49.5% CO 2 , 1% CH 4 , at 4 atm absolute pressure. The mean spatial resolution averaged over all tubes was 45 μm. The time to distance relation for this gas mixture, along with the geometric positioning of individual wires relative to the central tracking chamber, was obtained with data from Bhabha scattering events. We also describe resolution studies performed with a prototype chamber in a SLAC test beam. A wide range of gases, gas pressures, and electronic parameters were explored. These studies proved that resolutions in the 10–50 μm range were possible. Our experience demonstrates that chambers of this type provide high precision tracking and are particularly suited for operation in regions with difficult physical access and/or high ambient radiation levels.

A sample of events from the process e/sup +/e/sup -/..-->..tau/sup +/tau/sup -/ observed with the MAC detector operating at the SLAC storage ring PEP is used for a precise measurement of B/sub ..pi../, the branching fraction for the decay tau..--> nu../sub tau/..pi... The result B/sub ..pi../ = 0.107 +- 0.005 +- 0.008 is obtained from a sample of events with 798 identified pions.

We present measurements of forward-backward energy asymmetries of tau-lepton decay products from the reaction e/sup +/e/sup -/..-->..tau/sup +/tau/sup -/ in data collected with the MAC detector operating at the SLAC storage ring PEP at a center-of-mass energy of 29 GeV. The energy asymmetries for the decays tau..--> nu../sub tau/enu-bar/sub e/, tau..--> nu../sub tau/..mu..nu-bar/sub ..mu../, tau..--> nu../sub tau/..pi.., and tau..--> nu../sub tau/rho are interpreted as effects caused by the combination of maximally parity-violating weak tau decays and a longitudinal polarization produced by the interference of electromagnetic and weak processes. From the forward-backward polarization asymmetry A/sub P/ = (0.06 +- 0.07) x (1 +- 0.011), we determine the coupling-constant product g/sub a//sup e/g/sub v//sup tau/ = (0.26 +- 0.31) x (1 +- 0.011). Assuming g/sub a//sup e/ = -(1/2 as expected, we find g/sup tau//sub v/ = (-0.52 +- 0.62) x (1 +- 0.011), consistent with the prediction of the Glashow-Weinberg-Salam model of electroweak interactions. Alternatively, assuming the standard-model prediction of negligible polarization in tau-pair production, the leptonic energy spectra are used to measure the Michel parameter to be 0.79 +- 0.10 +- 0.10, consistent with the V-A hypothesis for the taunu-bar/sub tau/-W vertex.

We reports the result of a study of a tau decays with three pions in the final state (τ±→π±π+π−υτ and τ ±→π±π0π0υτ) from data accumulated with the MAC detector operating at the PEP storage ring. The branching fractions for these modes are measured to be 0.070±0.003±0.007 and, with assumptions discussed in the text, 0.087±0.004±0.011, respectively. Assuming that these final states result from the decay of the a1 meson, we measure the resonant parameters of the a1 with the three charged pion sample to be ma1=1166±18±11 MeV and γa1=405±75±25 MeV, and with the one charged plus two neutral pions sample to be ma1=1164±41±23 MeV and γa1=419±108±57 MeV.

A search for monojet production in e/sup +/e/sup -/ annihilation has been performed at ..sqrt..s = 29 GeV with the MAC detector at PEP. No events beyond those expected from tau decays have been found. The result has been interpreted as an upper limit for Z/sup 0/ decays into monojets, giving an upper limit for the branching ratio of 0.5% at the 90% confidence level. This limit excludes an interpretation that the monojets discovered by Arnison et al. are due to Z/sup 0/ decays into light Higgs pairs.

Precise measurements are reported for the leptonic branching ratios of the T lepton from the reaction e+e+ T+Tobserved with the MAC detector operating at PEP. Results from samples in which one T decays into three charged particles and the other to e or /,L are B, = 0.180 f 0.009 f 0.006 and B, = 0.183f0.009f0.005. A sample of ep events gives Be-B, = 0.0288f0.0017f0.0019. With the assumption of e-p universality these results are combined to give B, = 0.178 f 0.005 which implies a T lifetime of (2.85 f 0.09) x lo-l3 sec. PACS numbers: 14.6O.Jj, 13.35.+s

Data accumulated with a high-precision vertex drift chamber operating in the MAC detector at the SLAC storage ring PEP are used for a precise measurement of the lifetime of the \ensuremath{\tau} lepton. We measure decay lengths of a sample of reconstructed three-prong decay vertices, and impact parameters of a separate sample of decay tracks. Combining these results, we find that ${\ensuremath{\tau}}_{\ensuremath{\tau}}$=0.309\ifmmode\pm\else\textpm\fi{}0.019 ps, in agreement with the prediction from the measured leptonic branching ratio and \ensuremath{\tau}-\ensuremath{\mu} universality.

We have measured the mean lifetime of the hadrons containing b quarks that are produced in ${e}^{+}$${e}^{\mathrm{\ensuremath{-}}}$ annihilation at \ensuremath{\surd}s =29 GeV. We use the full sample of data collected by the MAC detector at the SLAC storage ring, PEP, including those recently acquired with a precision vertex detector. The result is ${\ensuremath{\tau}}_{b}$=[1.29\ifmmode\pm\else\textpm\fi{}0.20(stat) \ifmmode\pm\else\textpm\fi{}0.07(syst) ps]\ifmmode\times\else\texttimes\fi{}(1.00\ifmmode\pm\else\textpm\fi{}0.15), where the last factor is the systematic uncertainty in the scale.