1,177 research outputs found
Supramolecularly directed rotary motion in a photoresponsive receptor
Stimuli-controlled motion at the molecular level has fascinated chemists already for several decades. Taking inspiration from the myriad of dynamic and machine-like functions in nature, a number of strategies have been developed to control motion in purely synthetic systems. Unidirectional rotary motion, such as is observed in ATP synthase and other motor proteins, remains highly challenging to achieve. Current artificial molecular motor systems rely on intrinsic asymmetry or a specific sequence of chemical transformations. Here, we present an alternative design in which the rotation is directed by a chiral guest molecule, which is able to bind non-covalently to a light-responsive receptor. It is demonstrated that the rotary direction is governed by the guest chirality and hence, can be selected and changed at will. This feature offers unique control of directional rotation and will prove highly important in the further development of molecular machinery
Search for rare quark-annihilation decays, B --> Ds(*) Phi
We report on searches for B- --> Ds- Phi and B- --> Ds*- Phi. In the context
of the Standard Model, these decays are expected to be highly suppressed since
they proceed through annihilation of the b and u-bar quarks in the B- meson.
Our results are based on 234 million Upsilon(4S) --> B Bbar decays collected
with the BABAR detector at SLAC. We find no evidence for these decays, and we
set Bayesian 90% confidence level upper limits on the branching fractions BF(B-
--> Ds- Phi) Ds*- Phi)<1.2x10^(-5). These results
are consistent with Standard Model expectations.Comment: 8 pages, 3 postscript figues, submitted to Phys. Rev. D (Rapid
Communications
Measurement of the branching fraction for
We present a measurement of the branching fraction for the decay B- --> D0 K*- using a sample of approximately 86 million BBbar pairs collected by the BaBar detector from e+e- collisions near the Y(4S) resonance. The D0 is detected through its decays to K- pi+, K- pi+ pi0 and K- pi+ pi- pi+, and the K*- through its decay to K0S pi-. We measure the branching fraction to be B.F.(B- --> D0 K*-)= (6.3 +/- 0.7(stat.) +/- 0.5(syst.)) x 10^{-4}
Observation of a significant excess of events in B meson decays
We present an observation of the decay based on a sample of 124 million pairs recorded by the BABAR detector at the PEP-II asymmetric-energy Factory at SLAC. We observe events, where the first error is statistical and the second is systematic, corresponding to a significance of 4.2 standard deviations including systematic uncertainties. We measure the branching fraction \BR(B^{0} \to \pi^{0} \pi^{0}) = (2.1 \pm 0.6 \pm 0.3) \times 10^{-6}, averaged over and decays
Advanced small cell carcinoma of the uterine cervix treated by neoadjuvant chemotherapy with irinotecan and cisplatin followed by radical surgery
Small cell carcinoma of the uterine cervix is a rare form of cervical cancer characterized by extreme aggressiveness and poor prognosis because of its rapid growth, frequent distant metastases, and resistance to conventional treatment modalities. We report here a case of advanced-stage small cell carcinoma of the uterine cervix treated by neoadjuvant chemotherapy, followed by radical surgery, resulting in locoregional disease control. A 39-year-old Japanese woman was diagnosed as having stage IIIb small cell carcinoma of the uterine cervix. She was treated by neoadjuvant chemotherapy with irinotecan/cisplatin, followed by extended radical hysterectomy with pelvic and paraaortic lymphadenectomy. The patient was further treated by adjuvant chemotherapy with irinotecan/cisplatin. Intrapelvic recurrence has not been detected throughout the postoperative course. However, the patient died with distant metastases of the disease, 27 months following the initial treatment. It has been suggested that neoadjuvant chemotherapy therapy followed by radical surgery is a treatment option for advanced-stage small cell carcinoma of the uterine cervix for the locoregional disease control. Further studies are necessary to obtain information regarding multimodal treatment including sequence, duration, frequency, and type of effective chemotherapy agents to be used in the treatment of small cell carcinoma of the uterine cervix
Population growth rate of dry bulb mite, Aceria tulipae (Acariformes: Eriophyidae), on agriculturally important plants and implications for its taxonomic status
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Measurements of Branching Fractions and CP-Violating Asymmetries in B0→π+π-, K+π-, K+K- Decays
We present measurements of branching fractions and CP-violating asymmetries for two-body neutral B meson decays to charged pions and kaons based on a sample of about 88x10(6) Upsilon(4S)-->BB decays. From a time-independent fit we measure the charge-averaged branching fractions B(B0-->pi+pi-)=(4.7+/-0.6+/-0.2)x10(-6), B(B0-->K+pi-)=(17.9+/-0.9+/-0.7)x10(-6), and the direct CP-violating charge asymmetry A(Kpi)=-0.102+/-0.050+/-0.016 [-0.188,-0.016], where the ranges in square brackets indicate the 90% confidence intervals. From a time-dependent fit we measure the B0-->pi+pi- CP-violating parameters S(pipi)=0.02+/-0.34+/-0.05 [-0.54,+0.58] and C(pipi)=-0.30+/-0.25+/-0.04 [-0.72,+0.12]
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Study of the τ-→3h-2h+ντ decay
The branching fraction of the τ-→3h-2h+ντ decay (h=π,K) is measured with the BABAR detector to be (8.56±0.05±0.42) ×10-4, where the first error is statistical and the second systematic. The observed structure of this decay is significantly different from the phase space prediction, with the ρ resonance playing a strong role. The decay τ-→f1(1285)π-ντ, with the f1(1285) meson decaying to four charged pions, is observed and the branching fraction is measured to be (3.9±0.7±0.5)×10-4. © 2005 The American Physical Society
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Measurement of the branching fraction and decay rate asymmetry of B-→Dπ+π-π0K-
We report the observation of the decay B-→Dπ+π-π0K-, where Dπ+π-π0 indicates a neutral D meson detected in the final state π+π-π0, excluding KS0π0. This doubly Cabibbo-suppressed decay chain can be used to measure the CKM phase γ. Using about 229×106 e+e-→BB̄ events recorded by the BABAR experiment at the PEP-II e+e- storage ring, we measure the branching fraction B(B-→Dπ+π-π0K-)= (5.5±1.0(stat.)±0.7(syst.))×10-6 and the decay rate asymmetry A(B-→Dπ+π-π0K-)=-0.02±0.16(stat.)±0. 03(syst.) for the full decay chain. © 2005 The American Physical Society
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