Explicitly correlated trial wave functions in Quantum Monte Carlo calculations of excited states of Be and Be-

We present a new form of explicitly correlated wave function whose parameters are mainly linear, to circumvent the problem of the optimization of a large number of non-linear parameters usually encountered with basis sets of explicitly correlated wave functions. With this trial wave function we succeeded in minimizing the energy instead of the variance of the local energy, as is more common in quantum Monte Carlo methods. We applied this wave function to the calculation of the energies of Be 3P (1s22p2) and Be- 4So (1s22p3) by variational and diffusion Monte Carlo methods. The results compare favorably with those obtained by different types of explicitly correlated trial wave functions already described in the literature. The energies obtained are improved with respect to the best variational ones found in literature, and within one standard deviation from the estimated non-relativistic limitsComment: 19 pages, no figures, submitted to J. Phys.

Nonstomatal limitations are responsible for drought-induced photosynthetic inhibition in four C4 grasses

Here, the contribution of stomatal and nonstomatal factors to photosynthetic inhibition under water stress in four tropical C(4) grasses was investigated (Panicum coloratum, Bothriochloa bladhii, Cenchrus ciliaris and Astrebla lappacea ). Plants were grown in well watered soil, and then the effects of soil drying were measured on leaf gas exchange, chlorophyll a fluorescence and water relations. During the drying cycle, leaf water potential (Psi(leaf)) and relative water content (RWC) decreased from c. -0.4 to -2.8 MPa and 100-40%, respectively. The CO(2) assimilation rates (A) and quantum yield of PSII (Phi(PSII)) of all four grasses decreased rapidly with declining RWC. High CO(2) concentration (2500 mul l(-1)) had no effect on A or Phi(PSII) at any stage of the drying cycle. Electron transport capacity and dark respiration rates were unaltered by drought. The CO(2) compensation concentrations of P. coloratum and C. ciliaris rose sharply when leaf RWC fell below 70%. In P. coloratum, 5% CO(2) did not prevent the decline of O(2) evolution rates under water stress. We conclude that inhibition of photosynthesis in the four C(4) grasses under water stress is dependent mainly on biochemical limitations

Monte Carlo energy and variance minimization techniques for optimizing many-body wave functions

We investigate Monte Carlo energy and variance minimization techniques for optimizing many-body wave functions. Several variants of the basic techniques are studied, including limiting the variations in the weighting factors which arise in correlated sampling estimations of the energy and its variance. We investigate the numerical stability of the techniques and identify two reasons why variance minimization exhibits superior numerical stability to energy minimization. The characteristics of each method are studied using a non-interacting 64-electron model of crystalline silicon. While our main interest is in solid state systems, the issues investigated are relevant to Monte Carlo studies of atoms, molecules and solids. We identify a robust and efficient variance minimization scheme for optimizing wave functions for large systems.Comment: 14 pages, including 7 figures. To appear in Phys. Rev. B. For related publications see http://www.tcm.phy.cam.ac.uk/Publications/many_body.htm

Perfectionism and achievement goals in young Finnish ice-hockey players aspiring to make the Under-16 national team

Research on perfectionism suggests that is it useful to differentiate between perfectionistic strivings and perfectionistic concerns. Regarding the 2 x 2 achievement goal framework, the usefulness of this differentiation was recently demonstrated in a study with university student athletes (Stoeber, Stoll, Pescheck, & Otto, 2008, Study 2), in which it was found that perfectionistic strivings were associated with mastery-approach and performance-approach goals and perfectionistic concerns with mastery-avoidance, performance-approach, and performance-avoidance goals. Because the study was largely exploratory and only used non-elite athletes, the aim of the present research was to replicate and extend these findings by investigating a sample of 138 young, elite ice-hockey players, while adding further measures of perfectionism and using structural equation modelling (SEM) to confirm the relationships between perfectionistic strivings, perfectionistic concerns,and the 2 x 2 achievement goals. The SEM results showed that, in elite athletes also, perfectionistic strivings are associated with mastery-approach and performance-approach goals, whereas perfectionistic concerns are associated with masteryavoidance, performance-approach, and performance-avoidance goals. Our findings corroborate the importance of differentiating between perfectionistic strivings and perfectionistic concerns when studying perfectionism in sports, because only perfectionistic concerns (and not perfectionistic strivings) are associated with maladaptive patterns of achievement goals

Site controlled red-yellow-green light emitting InGaN quantum discs on nano-tipped GaN rods

We report a method of growing site controlled InGaN multiple quantum discs (QDs) at uniform wafer scale on coalescence free ultra-high density (>80%) nanorod templates by metal organic chemical vapour deposition (MOCVD). The dislocation and coalescence free nature of the GaN space filling nanorod arrays eliminates the well-known emission problems seen in InGaN based visible light sources that these types of crystallographic defects cause. Correlative scanning transmission electron microscopy (STEM), energy-dispersive X-ray (EDX) mapping and cathodoluminescence (CL) hyperspectral imaging illustrates the controlled site selection of the red, yellow and green (RYG) emission at these nano tips. This article reveals that the nanorod tips’ broad emission in the RYG visible range is in fact achieved by manipulating the InGaN QD’s confinement dimensions, rather than significantly increasing the In%. This article details the easily controlled method of manipulating the QDs dimensions producing high crystal quality InGaN without complicated growth conditions needed for strain relaxation and alloy compositional changes seen for bulk planar GaN templates

Correction: Site controlled red-yellow-green light emitting InGaN quantum discs on nano-tipped GaN rods

Correction for 'Site controlled red-yellow-green light emitting InGaN quantum discs on nano-tipped GaN rods' by M. Conroy et al., Nanoscale, 2016, 8 , 11019-11026

The growth and assembly of a massive galaxy at z ~ 2

We study the stellar mass assembly of the Spiderweb Galaxy (MRC 1138-262), a massive z = 2.2 radio galaxy in a protocluster and the probable progenitor of a brightest cluster galaxy. Nearby protocluster galaxies are identified and their properties are determined by fitting stellar population models to their rest-frame ultraviolet to optical spectral energy distributions. We find that within 150 kpc of the radio galaxy the stellar mass is centrally concentrated in the radio galaxy, yet most of the dust-uncorrected, instantaneous star formation occurs in the surrounding low-mass satellite galaxies. We predict that most of the galaxies within 150 kpc of the radio galaxy will merge with the central radio galaxy by z = 0, increasing its stellar mass by up to a factor of ~ 2. However, it will take several hundred Myr for the first mergers to occur, by which time the large star formation rates are likely to have exhausted the gas reservoirs in the satellite galaxies. The tidal radii of the satellite galaxies are small, suggesting that stars and gas are being stripped and deposited at distances of tens of kpc from the central radio galaxy. These stripped stars may become intracluster stars or form an extended stellar halo around the radio galaxy, such as those observed around cD galaxies in cluster cores.Comment: 12 pages, accepted for publication in MNRA

Epidemiology and natural history of central venous access device use and infusion pump function in the NO16966 trial

Background: Central venous access devices in fluoropyrimidine therapy are associated with complications; however, reliable data are lacking regarding their natural history, associated complications and infusion pump performance in patients with metastatic colorectal cancer.<p></p> Methods: We assessed device placement, use during treatment, associated clinical outcomes and infusion pump perfomance in the NO16966 trial.<p></p> Results: Device replacement was more common with FOLFOX-4 (5-fluorouracil (5-FU)+oxaliplatin) than XELOX (capecitabine+oxaliplatin) (14.1% vs 5.1%). Baseline device-associated events and post-baseline removal-/placement-related events occurred more frequently with FOLFOX-4 than XELOX (11.5% vs 2.4% and 8.5% vs 2.1%). Pump malfunctions, primarily infusion accelerations in 16% of patients, occurred within 1.6–4.3% of cycles. Fluoropyrimidine-associated grade 3/4 toxicity was increased in FOLFOX-4-treated patients experiencing a malfunction compared with those who did not (97 out of 155 vs 452 out of 825 patients), predominantly with increased grade 3/4 neutropenia (53.5% vs 39.8%). Febrile neutropenia rates were comparable between patient cohorts±malfunction. Efficacy outcomes were similar in patient cohorts±malfunction.<p></p> Conclusions: Central venous access device removal or replacement was common and more frequent in patients receiving FOLFOX-4. Pump malfunctions were also common and were associated with increased rates of grade 3/4 haematological adverse events. Oral fluoropyrimidine-based regimens may be preferable to infusional 5-FU based on these findings

The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/VIRGO GW170817. VII. Properties of the Host Galaxy and Constraints on the Merger Timescale

We present the properties of NGC 4993, the host galaxy of GW170817, the first gravitational wave (GW) event from the merger of a binary neutron star (BNS) system and the first with an electromagnetic (EM) counterpart. We use both archival photometry and new optical/near-IR imaging and spectroscopy, together with stellar population synthesis models to infer the global properties of the host galaxy. We infer a star formation history peaked at $\gtrsim 10$ Gyr ago, with subsequent exponential decline leading to a low current star formation rate of 0.01 M$_{\odot}$ yr$^{-1}$, which we convert into a binary merger timescale probability distribution. We find a median merger timescale of $11.2^{+0.7}_{-1.4}$ Gyr, with a 90% confidence range of $6.8-13.6$ Gyr. This in turn indicates an initial binary separation of $\approx 4.5$ R$_{\odot}$, comparable to the inferred values for Galactic BNS systems. We also use new and archival $Hubble$ $Space$ $Telescope$ images to measure a projected offset of the optical counterpart of $2.1$ kpc (0.64$r_{e}$) from the center of NGC 4993 and to place a limit of $M_{r} \gtrsim -7.2$ mag on any pre-existing emission, which rules out the brighter half of the globular cluster luminosity function. Finally, the age and offset of the system indicates it experienced a modest natal kick with an upper limit of $\sim 200$ km s$^{-1}$. Future GW$-$EM observations of BNS mergers will enable measurement of their population delay time distribution, which will directly inform their viability as the dominant source of $r$-process enrichment in the Universe.Comment: 9 Pages, 3 Figures, 2 Tables, ApJL, In Press. Keywords: GW170817, LV