Measurement of the mass difference between t and t quarks

We present a direct measurement of the mass difference between t and t quarks using tt candidate events in the lepton+jets channel, collected with the CDF II detector at Fermilab's 1.96 TeV Tevatron pp Collider. We make an event by event estimate of the mass difference to construct templates for top quark pair signal events and background events. The resulting mass difference distribution of data is compared to templates of signals and background using a maximum likelihood fit. From a sample corresponding to an integrated luminosity of 5.6  fb(-1), we measure a mass difference, ΔM(top) = M(t) - M(t) = -3.3 ± 1.4(stat) ± 1.0(syst)  GeV/c2, approximately 2 standard deviations away from the CPT hypothesis of zero mass difference.

Search for heavy bottomlike quarks decaying to an electron or muon and jets in pp collisions at √s = 1.96 TeV

We report the most sensitive direct search for pair production of fourth-generation bottomlike chiral quarks (b') each decaying promptly to tW. We search for an excess of events with an electron or muon, at least five jets (one identified as due to a b or c quark), and an imbalance of transverse momentum by using data from pp collisions collected by the CDF II detector at Fermilab with an integrated luminosity of 4.8  fb(-1). We observe events consistent with background expectation, calculate upper limits on the b' pair-production cross section (σ(bb')) ≲30  fb for m(b') > 375  GeV/c2), and exclude m(b') < 372  GeV/c2 at 95% confidence level assuming a 100% branching ratio of b' to tW.

Measurement of b hadron lifetimes in exclusive decays containing a J/ψ in pp collisions at √s=1.96 TeV

We report on a measurement of b-hadron lifetimes in the fully reconstructed decay modes B(+)→J/ψK(+), B⁰→J/ψK*(892)⁰, B⁰→J/ψK(s)⁰, and Λ(b)⁰→J/ψΛ⁰ using data corresponding to an integrated luminosity of 4.3 fb⁻¹, collected by the CDF II detector at the Fermilab Tevatron. The measured lifetimes are τ(B(+))=[1.639±0.009(stat)±0.009(syst)] ps, τ(B⁰)=[1.507±0.010(stat)±0.008(syst)] ps, and τ(Λ(b)⁰)=[1.537±0.045(stat)±0.014(syst)] ps. The lifetime ratios are τ(B(+))/τ(B⁰)=[1.088±0.009(stat)±0.004(syst)] and τ(Λ(b)⁰)/τ(B⁰)=[1.020±0.030(stat)±0.008(syst)]. These are the most precise determinations of these quantities from a single experiment.

Search for high mass resonances decaying to muon pairs in √s=1.96 TeV pp collisions

We present a search for a new narrow, spin-1, high mass resonance decaying to μ(+)μ⁻+X, using a matrix-element-based likelihood and a simultaneous measurement of the resonance mass and production rate. In data with 4.6 fb⁻¹ of integrated luminosity collected by the CDF detector in pp collisions at √s=1960 GeV, the most likely signal cross section is consistent with zero at 16% confidence level. We therefore do not observe evidence for a high mass resonance and place limits on models predicting spin-1 resonances, including M>1071 GeV/c² at 95% confidence level for a Z' boson with the same couplings to fermions as the Z boson.

Association of Rex-1 to target genes supports its interaction with Polycomb function

Rex-1/Zfp42 displays a remarkably restricted pattern of expression in preimplantation embryos, primary spermatocytes, and undifferentiated mouse embryonic stem (ES) cells and is frequently used as a marker gene for pluripotent stem cells. To understand the role of Rex-1 in selfrenewal and pluripotency, we used Rex-1 association as a measure to identify potential target genes, and carried out chromatin-immunoprecipitation assays in combination with gene specific primers to identify genomic targets Rex-1 associates with. We find association of Rex-1 to several genes described previously as bivalently marked regulators of differentiation and development, whose repression in mouse embryonic stem (ES) cells is Polycomb Group-mediated, and controlled directly by Ring1A/B. To substantiate the hypothesis that Rex-1 contributes to gene regulation by PcG, we demonstrate interactions of Rex-1 and YY2 (a close relative of YY1) with Ring1 proteins and the PcG-associated proteins RYBP and YAF2, in line with interactions reported previously for YY1. We also demonstrate the presence of Rex-1 protein in both trophectoderm and Inner Cell Mass of the mouse blastocyst and in both ES and in trophectoderm stem (TS) cells. In TS cells, we were unable to demonstrate association of Rex-1 to the genes it associates with in ES cells, suggesting that association may be cell-type specific. Rex-1 might fine-tune pluripotency in ES cells by modulating Polycomb-mediated gene regulation.

Top quark mass measurement in the lepton + jets channel using a matrix element method and in situ jet energy calibration

A precision measurement of the top quark mass m(t) is obtained using a sample of tt events from pp collisions at the Fermilab Tevatron with the CDF II detector. Selected events require an electron or muon, large missing transverse energy, and exactly four high-energy jets, at least one of which is tagged as coming from a b quark. A likelihood is calculated using a matrix element method with quasi-Monte Carlo integration taking into account finite detector resolution and jet mass effects. The event likelihood is a function of m(t) and a parameter Δ(JES) used to calibrate the jet energy scale in situ. Using a total of 1087 events in 5.6 fb(-1) of integrated luminosity, a value of m(t)=173.0 ± 1.2 GeV/c(2) is measured.

Improved search for a Higgs boson produced in association with Z → l+ l- in pp collisions sqrt[s] = 1.96 TeV

We search for the standard model Higgs boson produced with a Z boson in 4.1 fb(-1) of integrated luminosity collected with the CDF II detector at the Tevatron. In events consistent with the decay of the Higgs boson to a bottom-quark pair and the Z boson to electrons or muons, we set 95% credibility level upper limits on the ZH production cross section multiplied by the H → bb branching ratio. Improved analysis methods enhance signal sensitivity by 20% relative to previous searches. At a Higgs boson mass of 115 GeV/c2 we set a limit of 5.9 times the standard model cross section.

Abstract P2-09-27: Predictive Factors of Complete Axillary Downstaging after Neoadjuvant Chemotherapy in Breast Cancer Patients

Background: The axillary status after neoadjuvant chemotherapy (NACT) is an important prognostic factor. Complete axillary downstaging (CAD) occurs in up to 20-30% of the patients, however, sentinel node biopsy after NACT is not recommended in patients with initial axillary nodal involvement and complete axillary response after NACT. Our aim was to investigate predictive factors of CAD after NACT to identify patients who could avoid an unnecessary axillary dissection. Patients and methods: From January 2004 to December 2008, 256 consecutive patients were diagnosed with invasive breast cancer and received NACT and breast surgery at our institution. Patients were eligible for this analysis if they met the following inclusion criteria: clinically and/or cytologically proven metastatic axillary nodes; complete axillary response after NACT; and complete axillary dissection after systemic treatment. CAD was defined as pN0 (isolated tumor cells and micrometastasis were excluded). Univariate and multivariate analyses were performed to assess the association between CAD and either tumor characteristics or intrinsic cancer subtypes.

Results: 84 patients were included. Median age was 51.64 years. 75 (89,3%) received anthracyclines-and taxanes-based CT and 11 (13%). 38 (45,2%) had cytologically proven metastatic axillary nodes at diagnosis. According to intrinsic cancer subtypes, 22 (26%) were classified as HER2 positive, 17 (20,2%) as triple negative (ER, PR, and HER2 -), 6 (7,1%) as luminal A [estrogen receptor positive and/or progesterone receptor positive and (Ki67 &lt; 20% and histological grade 1 or 2)], and 23 (27,4%) as luminal B [estrogen receptor positive and/or progesterone receptor positive and (Ki67 ≥20% or histological grade 3)]. In the univariate analysis, HER2 positivity (p=0,002) and neoadjuvant treatment with trastuzumab (p=0,019) were significantly associated with CAD. In the multivariate analysis only HER2 status maintained statistical significance (p=0,003). Among luminal A, luminal B, and triple negative tumors, complete axillary response after NACT did not significantly predict CAD.

Conclusions: In our cohort of breast cancer patients, HER2 status is an independent predictive factor of CAD after NACT. Clinical trials, probably according to specific breast cancer subtypes, are required to identify patients with initial axillary metastatic involvement who could avoid an axillary dissection after systemic therapy.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P2-09-27.

Abstract P4-03-04: Body Mass Index as a Predictive Factor of Pathological Complete Response to Neoadjuvant Chemotherapy in Breast Cancer Patients

Background: Obesity has been associated with worse pathological complete response (pCR) to neoadjuvant chemotherapy (NACT) and overall outcome in breast cancer patients (pts). Our aim was to retrospectively evaluate body mass index (BMI) as a predictive factor of pCR to NACT in pts treated at our institution, taking into account tumor HER2 status and CT dose adjustment.

Pts and methods: Pts with invasive breast cancer who received NACT followed by surgery at Vall d'Hebron University Hospital from January 2004 to December 2008 were analyzed. Pts were categorized as normal/underweight (BMI &lt; 25 kg/m2), overweight (BMI of 25 to &lt; 30 kg/m2), and obese (BMI ≥30 kg/m2). The overweight and obese groups were combined (BMI-high) and then compared with the normal/underweight group. Univariate and multivariate analyses were performed to assess the association between BMI and pCR (no invasive tumor in breast and nodes).

Results: 256 consecutive pts were included. Median age was 52.5 years. According to BMI, 38.7% were normal/underweight and 59.4% were BMI-high. 23.4% of the pts had HER2 positive tumors (n=60), 84% received anthracyclines-and taxanes-based CT, and 46.6% of the HER2 positive pts were treated with trastuzumab. Drug dose was reduced in only five pts with a body surface area &gt; 2m2. No statistically significant association was found between BMI and any tumor characteristics. In the univariate analysis, BMI-high was associated with worse pCR in the whole population (p=0.017), as well as in HER2 positive pts (p=0.013). In the multivariate analysis, BMI did not significantly predict pCR in the total population, although a trend was observed (p=0.098). In the HER2 positive subgroup, however, BMI was an independent predictive factor of pCR (p=0.001). Among luminal A [estrogen receptor positive and/or progesterone receptor positive and (Ki67 &lt; 20% and histological grade 1 or 2)], luminal B [estrogen receptor positive and/or progesterone receptor positive and (Ki67 ≥20% or histological grade 3)], and triple negative tumors, BMI was not a predictive factor of pCR.

Conclusions: Our results suggest that higher BMI is likely associated with worse pCR, particularly in HER2 positive pts. A better understanding of the molecular links between obesity and breast cancer is necessary to identify new predictive factors of pCR to NACT.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P4-03-04.

Direct top-quark width measurement at CDF

We present a measurement of the top-quark width in the lepton+jets decay channel of tt events produced in p p collisions at Fermilab's Tevatron collider and collected by the CDF II detector. From a data sample corresponding to 4.3 fb(-1) of integrated luminosity, we identify 756 candidate events. The top-quark mass and the mass of the hadronically decaying W boson that comes from the top-quark decay are reconstructed for each event and compared with templates of different top-quark widths (Γ(t)) and deviations from nominal jet energy scale (Δ(JES)) to perform a simultaneous fit for both parameters, where Δ(JES) is used for the in situ calibration of the jet energy scale. By applying a Feldman-Cousins approach, we establish an upper limit at 95% confidence level (CL) of Γ(t) <7.6 GeV and a two-sided 68% CL interval of 0.3 GeV <Γ(t) <4.4  GeV for a top-quark mass of 172.5 GeV/c(2), which are consistent with the standard model prediction.

Search for R-parity violating decays of sneutrinos to eμ, μτ, and eτ pairs in pp collisions at square root s = 1.96 TeV

We present a search for supersymmetric neutrino ν production using the Tevatron pp collision data collected with the CDF II detector and corresponding to an integrated luminosity of 1 fb-1. We focus on the scenarios predicted by the R-parity violating (RPV) supersymmetric models in which sneutrinos decay to two charged leptons of different flavor. With the data consistent with the standard model expectations, we set upper limits on σ(pp→ν)×BR(ν→eμ,μτ,eτ) and use these results to constrain the RPV couplings as a function of the sneutrino mass.

Multidimensional analysis of treatment adherence in patients with multiple chronic conditions. A cross-sectional study in a tertiary hospital

OBJECTIVE

Determine treatment adherence in patients with multiple chronic conditions (MCC).

METHODS

A random patient sample ≥ 15 years, discharged from hospital with ≥1 chronic conditions (CC) was interviewed after 6-12 months. Analysis included variables in 5 dimensions (WHO): socio-demographics, disease, treatment, patient and health system characteristics. Morisky-Green adherence questionnaire was used. High chronic treatment complexity was defined as: >3 pills/day, >6 inhalations/day, >1 injection/day, pharmacological treatment plus diet or self-monitoring techniques.

RESULTS

301 patients were interviewed (62 ± 15 years, 59% males). Despite good treatment information perception (79%), only 3% followed the patient education programme. Poor adherents (82%) were older (64 ± 14 years vs. 55 ± 16 years), had more CC (3.25 ± 2.02 vs. 2.62 ± 2.72), a higher frequency of hypertension (44% vs. 15%), ischaemic heart diseases: (21% vs. 4%), hyperlipidaemia (19% vs. 6%), more pills/day (5.78 ± 4.14 vs. 3.20 ± 4.70) and more complex treatments (95% vs. 70%) (p<0.05). On multivariate analysis number of CC [3.68 (0.75-18.15)], pills/day [2.23 (1.02-4.84)], treatment complexity [4.00 (1.45-11.04)], and hypertension [2.57 (1.06-6.25)] were predictive of poor adherence (OR 95% CI p<0.05).

CONCLUSION

The WHO conceptual framework allows the construction of poor adherence risk profiles in patients with MCC after hospital discharge.

PRACTICE IMPLICATIONS

Predictive variables of poor adherence could help clinicians detect patients with MCC most likely to present poor adherence.

Comparison of laboratory methodologies for evaluating radiostrontium diffusion in soils: planar-source versus half-cell methods

A planar-source method, initially designed to obtain diffusion coefficients in compacted clay, is adapted here to determine the apparent diffusion coefficient (D(a)) of radiostrontium in soils representative of the Spanish territory. Experiments were carried out by varying the moisture content (F(moist)), and bulk dry density (ρ(bulk)) of the soil samples, in order to study the influence of these soil packing parameters on D(a) values. The moisture in the soil samples was established as the percentage of occupancy of each soil's field capacity (OFC). For a similar OFC, D(a) values in the examined soils ranged by approximately one order of magnitude (e.g. from 6.2 × 10(-)(11) to 6.5 × 10(-)(12)m(2)s(-)(1), at 100% of OFC; from 3.0 × 10(-)(11) to 3.8 × 10(-)(12)m(2)s(-)(1), at 60% of OFC). For a given soil, D(a) values increased when water content was increased. F(moist), and tortuosity (τ) explained D(a) variability, with R(2) values usually over 0.9. However, no good simple or multiple regressions between the soil packing parameters and D(a) were obtained with the whole dataset of all soils, which indicated that soil sorption capacity affects the diffusion of reactive radionuclides in soils. The inclusion of calculated K(d) values in the multiple regressions improved the correlations in all cases. Finally, D(a) values were compared with those obtained by the application of a half-cell method. The values of D(a) obtained by the planar-source methods were systematically lower than the half-cell ones, with a good correlation between the D(a) derived from both methods (R(2)=0.98).

Search for new physics with a dijet plus missing E(T) signature in pp collisions at √s=1.96 TeV

We present results of a signature-based search for new physics using a dijet plus missing transverse energy (E(T)) data sample collected in 2  fb⁻¹ of pp collisions at √s=1.96  TeV with the CDF II detector at the Fermilab Tevatron. We observe no significant event excess with respect to the standard model prediction and extract a 95% C.L. upper limit on the cross section times acceptance for a potential contribution from a nonstandard model process. The search is made by using novel, data-driven techniques for estimating backgrounds that are applicable to first searches at the LHC.

Diffusion experiments for estimating radiocesium and radiostrontium sorption in unsaturated soils from Spain: comparison with batch sorption data

As sorption data obtained from batch tests are often used to estimate pollutant transport in unsaturated soils, comparison between sorption data obtained in the two conditions is required to ensure a correct risk assessment. With this aim, radiostrontium and radiocesium apparent diffusion coefficients (D(a)) were quantified in nine unsaturated soils, and the derived distribution coefficients (K(d)) were compared with K(d) data from batch experiments. The D(a)(Sr) and the D(a)(Cs) ranged from 1.8x10(-11) to 1.5x10(-10) m(2) s(-1), and from 1.0x10(-13) to 5.9x10(-11) m(2) s(-1), respectively. The D(a)(Sr) varied according to both soil packing parameters and properties governing Sr interaction. For Cs, the soil sorption properties explained the variation on D(a)(Cs). The K(d) values derived from D(a) (from 0.014 to 1.8 L kg(-1) for Sr; from 0.55 to 942 L kg(-1) for Cs) were lower than from batch tests (from 1 to 97 L kg(-1) for Sr; from 10 to 14,600 L kg(-1) for Cs), thus indicating that batch data may not accurately describe radionuclide transport in unsaturated soils. However, the two sets of data correlated well, thus suggesting that radionuclide transport can be estimated from batch tests, which are faster than diffusion experiments.

Exclusion of an exotic top quark with -4/3 electric charge using soft lepton tagging

We present a measurement of the electric charge of the top quark using pp collisions corresponding to an integrated luminosity of 2.7 fb(-1) at the CDF II detector. We reconstruct tt events in the lepton + jets final state. We use soft lepton taggers to determine the flavor of the b jets, which we use to reconstruct the top quark's electric charge and exclude an exotic top quark with -4/3 charge at 95% confidence level. This is the strongest exclusion of the exotic charge scenario and the first to use soft leptons for this purpose.

Search for the production of scalar bottom quarks in pp collisions at square root(s) = 1.96 TeV

We report on a search for direct scalar bottom quark (sbottom) pair production in pp collisions at square root(s) = 1.96 TeV, in events with large missing transverse energy and two jets of hadrons in the final state, where at least one of the jets is required to be identified as originating from a b quark. The study uses a collider detector at Fermilab Run II data sample corresponding to 2.65 fb(-1) of integrated luminosity. The data are in agreement with the standard model. In an R-parity conserving minimal supersymmetric scenario, and assuming that the sbottom decays exclusively into a bottom quark and a neutralino, 95% confidence-level upper limits on the sbottom pair production cross section of 0.1 pb are obtained. For neutralino masses below 70 GeV/c2, sbottom masses up to 230 GeV/c2 are excluded at 95% confidence level.

Measurement of W-boson polarization in Top-Quark Decay in pp collisions at sqrt[s]=1.96 TeV

We report measurements of the polarization of W bosons from top-quark decays using 2.7 fb{-1} of pp collisions collected by the CDF II detector. Assuming a top-quark mass of 175  GeV/c{2}, three measurements are performed. A simultaneous measurement of the fraction of longitudinal (f{0}) and right-handed (f{+}) W bosons yields the model-independent results f{0}=0.88±0.11(stat)±0.06(syst) and f{+}=-0.15±0.07(stat)±0.06(syst) with a correlation coefficient of -0.59. A measurement of f{0} [f{+}] constraining f{+} [f{0}] to its standard model value of 0.0 [0.7] yields f{0}=0.70±0.07(stat)±0.04(syst) [f{+}=-0.01±0.02(stat)±0.05(syst)]. All these results are consistent with standard model expectations. We achieve the single most precise measurements of f{0} for both the model-independent and model-dependent determinations.

Exosomes in erythropoiesis

Multivesicular endosomes contain membrane vesicles which can be released into the extracellular environment as exosomes. This review describes the role of exosome secretion in the remodeling of the red cell plasma membrane during the last stage of erythropoietic differentiation. Herein, we propose that the exosome biogenesis involves several mechanisms of protein sorting and leads to partial or complete loss of membrane activities, in some cases in a regulated way.

Measurement of the ratio σ{tt}/σ{Z/γ{*}→ll} and precise extraction of the tt cross section

We report a measurement of the ratio of the tt to Z/γ{*} production cross sections in sqrt[s]=1.96  TeV pp collisions using data corresponding to an integrated luminosity of up to 4.6  fb{-1}, collected by the CDF II detector. The tt cross section ratio is measured using two complementary methods, a b-jet tagging measurement and a topological approach. By multiplying the ratios by the well-known theoretical Z/γ{*}→ll cross section predicted by the standard model, the extracted tt cross sections are effectively insensitive to the uncertainty on luminosity. A best linear unbiased estimate is used to combine both measurements with the result σ{tt}=7.70±0.52  pb, for a top-quark mass of 172.5  GeV/c{2}.

Search for pair production of supersymmetric top quarks in dilepton events from pp collisions at sqrt[s]=1.96 TeV

We present the results of a search for pair production of the supersymmetric partner of the top quark (the top squark t{1}) decaying to a b quark and a chargino χ{1}{±} with a subsequent χ{1}{±} decay into a neutralino χ{1}{0}, lepton ℓ, and neutrino ν. Using a data sample corresponding to 2.7  fb{-1} of integrated luminosity of pp collisions at sqrt[s]=1.96  TeV collected by the CDF II detector, we reconstruct the mass of top squark candidate events and fit the observed mass spectrum to a combination of standard model processes and t{1}t{1} signal. We find no evidence for t{1}t{1} production and set 95% C.L. limits on the masses of the top squark and the neutralino for several values of the chargino mass and the branching ratio B(χ{1}{±}→χ{1}{0}ℓ{±}ν).