A regioselectivity switch in Pd-catalyzed hydroallylation of alkynes.

By exploiting the reactivity of a vinyl-Pd species, we control the regioselectivity in hydroallylation of alkynes under Pd-hydride catalysis. A monophosphine ligand and carboxylic acid combination promotes 1,5-dienes through a pathway involving isomerization of alkynes to allenes. In contrast, a bisphosphine ligand and copper cocatalyst favor 1,4-dienes via a mechanism that involves transmetalation. Our study highlights how to access different isomers by diverting a common organometallic intermediate

Active optical clock based on four-level quantum system

Active optical clock, a new conception of atomic clock, has been proposed recently. In this report, we propose a scheme of active optical clock based on four-level quantum system. The final accuracy and stability of two-level quantum system are limited by second-order Doppler shift of thermal atomic beam. To three-level quantum system, they are mainly limited by light shift of pumping laser field. These limitations can be avoided effectively by applying the scheme proposed here. Rubidium atom four-level quantum system, as a typical example, is discussed in this paper. The population inversion between $6S_{1/2}$ and $5P_{3/2}$ states can be built up at a time scale of $10^{-6}$s. With the mechanism of active optical clock, in which the cavity mode linewidth is much wider than that of the laser gain profile, it can output a laser with quantum-limited linewidth narrower than 1 Hz in theory. An experimental configuration is designed to realize this active optical clock.Comment: 5 page

First results of the new endcap TOF commissioning at BESIII

The upgrade of the current BESIII Endcap TOF (ETOF) is carried out with the Multi-gap Resistive Plate Chamber (MRPC) technology. The installation of the new ETOF has been finished in October 2015. The first results of the MRPCs commissioning at BESIII are reported in this paper.Comment: 7 pages,8 figures,conferenc

Strangeness in the proton and N*(1535)

The newest progress on the study of the strangeness in the proton and in the lowest negative parity nucleon excited state $N^*(1535)$ is reviewed. Implications on the internal quark structure of the proton, $N^*(1535)$ and other baryons are discussed. The diquark cluster picture for the 5-quark components in baryons gives a natural explanation not only to the empirical indications for a positive strangeness magnetic moment $\mu_s$ and positive strangeness radius of the proton but also the longstanding mass-reverse problem of $N^*(1535)$, $N^*(1440)$ and $\Lambda^*(1405)$ resonances as well as the unusual decay pattern of the $N^*(1535)$ resonance. Evidence for possible existence of $N^*(1535)$'s ${1/2}^-$ SU(3) nonet partners in this picture is pointed out, and suggestion is made to search for these $1/2^-$ hyperon excited states under the well known $\Sigma^*(1385)$, $\Lambda^*(1520)$ and $\Xi^*(1530)$ peaks in various reactions.Comment: 6 pages, 2 figures, Plenary talk at 18th International IUPAP Conference on Few-Body Problems in Physics August 21-26. 2006 Santos SP Brazil; to be published in Nuclear Physics

Small inhibitor of Bcl-2, HA14-1, selectively enhanced the apoptotic effect of cisplatin by modulating Bcl-2 family members in MDA-MB-231 breast cancer cells

Inhibition or downregulation of Bcl-2 represents a new therapeutic approach to by-pass chemoresistance in cancer cells. Therefore, we explored the potential of this approach in breast cancer cells. Cisplatin and paclitaxel induced apoptosis in a dose-dependent manner in MCF-7 (drug-sensitive) and MDA-MB-231 (drug-insensitive) cells. Furthermore, when we transiently silenced Bcl-2, both cisplatin and paclitaxel induced apoptosis more than parental cells. Dose dependent induction of apoptosis by drugs was enhanced by the pre-treatment of these cells with HA14-1, a Bcl-2 inhibitor. Although the effect of cisplatin was significant on both cell lines, the effect of paclitaxel was much less potent only in MDA-MB-231 cells. To further understand the distinct role of drugs in MDA-MB-231 cells pretreated with HA14-1, caspases and Bcl-2 family proteins were studied. The apoptotic effect of cisplatin with or without HA14-1 pre-treatment is shown to be caspase-dependent. Among pro-apoptotic Bcl-2 proteins, Bax and Puma were found to be up-regulated whereas Bcl-2 and Bcl-x(L) were down-regulated when cells were pretreated with HA14-1 followed by paclitaxel or cisplatin. Enforced Bcl-2 expression in MDA-MB-231 cells abrogated the sensitizing effect of HA14-1 in cisplatin induced apoptosis. These results suggest that the potentiating effect of HA14-1 is drug and cell type specific and may not only depend on the inhibition of Bcl-2. Importantly, alteration of other pro-apoptotic or anti-apoptotic Bcl-2 family members may dictate the apoptotic response when HA14-1 is combined with chemotherapeutic drugs

Impact of body-mass factors on setup displacement in patients with head and neck cancer treated with radiotherapy using daily on-line image guidance

BACKGROUND: To determine the impact of body-mass factors (BMF) before radiotherapy and changes during radiotherapy on the magnitude of setup displacement in patients with head and neck cancer (HNC). METHODS: The clinical data of 30 patients with HNC was analyzed using the alignment data from daily on-line on-board imaging from image-guided radiotherapy. BMFs included body weight, body height, and the circumference and bilateral thickness of the neck. Changes in the BMFs during treatment were retrieved from cone beam computed tomography at the 10th and 20th fractions. Setup errors for each patient were assessed by systematic error (SE) and random error (RE) through the superior-inferior (SI), anterior-posterior (AP), and medial-lateral (ML) directions, and couch rotation (CR). Using the median values of the BMFs as a cutoff, the impact of the factors on the magnitude of displacement was assessed by the Mann–Whitney U test. RESULTS: A higher body weight before radiotherapy correlated with a greater AP-SE (p = 0.045), SI-RE (p = 0.023), and CR-SE (p = 0.033). A longer body height was associated with a greater SI-RE (p = 0.002). A performance status score of 1 or 2 was related to a greater AP-SE (p = 0.043), AP-RE (p = 0.015), and SI-RE (p = 0.043). Among the ratios of the BMFs during radiotherapy, the values at the level of mastoid tip at the 20(th) fraction were associated with greater setup errors. CONCLUSIONS: To reduce setup errors in patients with HNC receiving RT, the use of on-line image-guided radiotherapy is recommended for patients with a large body weight or height, and a performance status score of 1–2. In addition, adaptive planning should be considered for those who have a large reduction ratio in the circumference (<1) and thickness (<0.94) over the level of the mastoid tip during the 20(th) fraction of treatment

Improved Constraints on Sterile Neutrino Mixing from Disappearance Searches in the MINOS, MINOS+, Daya Bay, and Bugey-3 Experiments.

Searches for electron antineutrino, muon neutrino, and muon antineutrino disappearance driven by sterile neutrino mixing have been carried out by the Daya Bay and MINOS+ collaborations. This Letter presents the combined results of these searches, along with exclusion results from the Bugey-3 reactor experiment, framed in a minimally extended four-neutrino scenario. Significantly improved constraints on the θ_{μe} mixing angle are derived that constitute the most constraining limits to date over five orders of magnitude in the mass-squared splitting Δm_{41}^{2}, excluding the 90%&nbsp;C.L. sterile-neutrino parameter space allowed by the LSND and MiniBooNE observations at 90%&nbsp;CL_{s} for Δm_{41}^{2}&lt;13  eV^{2}. Furthermore, the LSND and MiniBooNE 99%&nbsp;C.L. allowed regions are excluded at 99% CL_{s} for Δm_{41}^{2}&lt;1.6 eV^{2}

General CP Violation in Minimal Left-Right Symmetric Model and Constraints on the Right-Handed Scale

In minimal left-right symmetric theories, the requirement of parity invariance allows only one complex phase in the Higgs potential and one in the Yukawa couplings, leading to a two-phase theory with both spontaneous and explicit CP violations. We present a systematic way to solve the right-handed quark mixing matrix analytically in this model and find that the leading order solution has the same hierarchical structure as the left-handed CKM matrix with one more CP-violating phase coming from the complex Higgs vev. Armed with this explicit right-handed mixing matrix, we explore its implications for flavor changing and conserving processes in detail, low-energy CP-violating observables in particular. We report an improved lower bound on the $W_R$ mass of 2.5 TeV from $\Delta M_K$ and $\Delta M_{B}$, and a somewhat higher bound (4 TeV) from kaon decay parameters $\epsilon$, $\epsilon'$, and neutron electric dipole moment. The new bound on the flavor-changing neutral Higgs mass is 25 TeV.Comment: 35 pages, 14 figure

Reconstruction and measurement of (100) MeV energy electromagnetic activity from π0 arrow γγ decays in the MicroBooNE LArTPC

We present results on the reconstruction of electromagnetic (EM) activity from photons produced in charged current νμ interactions with final state π0s. We employ a fully-automated reconstruction chain capable of identifying EM showers of (100) MeV energy, relying on a combination of traditional reconstruction techniques together with novel machine-learning approaches. These studies demonstrate good energy resolution, and good agreement between data and simulation, relying on the reconstructed invariant π0 mass and other photon distributions for validation. The reconstruction techniques developed are applied to a selection of νμ + Ar → μ + π0 + X candidate events to demonstrate the potential for calorimetric separation of photons from electrons and reconstruction of π0 kinematics

Neutron Electric Dipole Moment Constraint on Scale of Minimal Left-Right Symmetric Model

Using an effective theory approach, we calculate the neutron electric dipole moment (nEDM) in the minimal left-right symmetric model with both explicit and spontaneous CP violations. We integrate out heavy particles to obtain flavor-neutral CP-violating effective Lagrangian. We run the Wilson coefficients from the electroweak scale to the hadronic scale using one-loop renormalization group equations. Using the state-of-the-art hadronic matrix elements, we obtain the nEDM as a function of right-handed W-boson mass and CP-violating parameters. We use the current limit on nEDM combined with the kaon-decay parameter $\epsilon$ to provide the most stringent constraint yet on the left-right symmetric scale $M_{W_R} > (10 \pm 3)$ TeV.Comment: 20 pages and 8 figure