Critically phase-matched Ti:sapphire-laserpumped deep-infrared femtosecond optical parametric oscillator based on CdSiP2

We report a high-repetition-rate femtosecond optical parametric oscillator (OPO) for the deep-infrared (deep-IR) based on type-I critical phase-matching in CdSiP2 (CSP), pumped directly by a Ti:sapphire laser. Using angle-tuning in the CSP crystal, the OPO can be continuously tuned across 7306–8329 nm (1201–1369  cm−1) in the deep-IR. It delivers up to 18 mW of idler average power at 7306 nm and >7  mW beyond 8000 nm at 80.5 MHz repetition rate, with the spectra exhibiting bandwidths of >150  nm across the tuning range. Moreover, the signal is tunable across 1128–1150 nm in the near-infrared, providing up to 35 mW of average power in ∼266  fs pulses at 1150 nm. Both beams exhibit single-peak Gaussian distribution in TEM00 spatial profile. With an equivalent spectral brightness of ∼5.6×1020photons s−1 mm−2 sr−10.1% BW−1, this OPO represents a viable alternative to synchrotron and supercontinuum sources for deep-IR applications in spectroscopy, metrology, and medical diagnostics.Peer ReviewedPostprint (author's final draft

Reconsidering laminate nonsymmetry

Nonsymmetric laminates are commonly precluded from composite design due to perceptions of reduced performance arising from in- and out-of-plane coupling. This coupling introduces warpage during cure—leading to raised stresses, together with diminished buckling and load carrying capacity. However, these reduced performance characteristics are rarely quantified and included in the design process; instead the symmetric-only paradigm remains pervasive at the cost of a significantly reduced design space. Warpage is largely driven by mismatch in the coefficients of thermal expansion between sublaminates located above and below the midplane and can be predicted by the classical laminate theory. Acknowledging that all symmetric laminates in multipart structures have build stresses from assembly, it is proposed that subsets of nonsymmetric laminates that translate to similar raised stress levels be considered for design. Challenging this symmetric-only design paradigm would permit greater design freedom and offer new routes to elastically tailor composite structures. Further analysis of structural performance is assessed in terms of reduced loading and buckling capacity

Fiber-Flux Diffusion Density for White Matter Tracts Analysis: Application to Mild Anomalies Localization in Contact Sports Players

We present the concept of fiber-flux density for locally quantifying white matter (WM) fiber bundles. By combining scalar diffusivity measures (e.g., fractional anisotropy) with fiber-flux measurements, we define new local descriptors called Fiber-Flux Diffusion Density (FFDD) vectors. Applying each descriptor throughout fiber bundles allows along-tract coupling of a specific diffusion measure with geometrical properties, such as fiber orientation and coherence. A key step in the proposed framework is the construction of an FFDD dissimilarity measure for sub-voxel alignment of fiber bundles, based on the fast marching method (FMM). The obtained aligned WM tract-profiles enable meaningful inter-subject comparisons and group-wise statistical analysis. We demonstrate our method using two different datasets of contact sports players. Along-tract pairwise comparison as well as group-wise analysis, with respect to non-player healthy controls, reveal significant and spatially-consistent FFDD anomalies. Comparing our method with along-tract FA analysis shows improved sensitivity to subtle structural anomalies in football players over standard FA measurements

A Fast and Accessible Methodology for Micro-Patterning Cells on Standard Culture Substrates Using Parafilm™ Inserts

Micropatterning techniques provide direct control over the spatial organization of cells at the sub-mm scale. Regulation of these spatial parameters is important for controlling cell fate and cell function. While micropatterning has proved a powerful technique for understanding the impact of cell organization on cell behaviour, current methods for micropatterning cells require complex, specialized equipment that is not readily accessible in most biological and bioengineering laboratories. In addition, currently available methods require significant protocol optimization to ensure reliable and reproducible patterning. The inaccessibility of current methods has severely limited the widespread use of micropatterning as a tool in both biology and tissue engineering laboratories. Here we present a simple, cheap, and fast method to micropattern mammalian cells into stripes and circular patterns using Parafilm™, a common material found in most biology and bioengineering laboratories. Our method does not require any specialized equipment and does not require significant method optimization to ensure reproducible patterning. Although our method is limited to simple patterns, these geometries are sufficient for addressing a wide range of biological problems. Specifically, we demonstrate i) that using our Parafilm™ insert method we can pattern and co-pattern ARPE-19 and MDCK epithelial cells into circular and stripe micropatterns in tissue culture polystyrene (TCPS) wells and on glass slides, ii) that we can contain cells in the desired patterns for more than one month and iii) that upon removal of the Parafilm™ insert we can release the cells from the containment pattern and allow cell migration outward from the original pattern. We also demonstrate that we can exploit this confinement release feature to conduct an epithelial cell wound healing assay. This novel micropatterning method provides a reliable and accessible tool with the flexibility to address a wide range of biological and engineering problems that require control over the spatial and temporal organization of cells

Priming reveals attentional modulation of human motion sensitivity

AbstractAlthough recent fMRI and single unit recording studies have shown that attention modulates neural activity in motion sensitive areas of extrastriate cortex, these approaches cannot reveal qualitative or quantitative effects of attention on perception of motion. To investigate this, we asked observers to select one of two orthogonal directions in a brief, transparent dot display (prime) and then measured their sensitivity to global directional motion in a second uni-directional dot display (probe) presented a short time later. When probe direction matched the attended prime direction, sensitivity was degraded. But, when probe direction matched the ignored prime direction, sensitivity was enhanced, even though both components were of equal physical strength. Sensitivity was unchanged for directions opposite to either previously seen direction. Neither sensory adaptation nor opponent direction mechanisms can account for these data. Rather, processes initiated by visual selection must underlie these dramatic changes in motion sensitivity

Re-circumscription of the mimosoid genus Entada including new combinations for all species of the phylogenetically nested Elephantorrhiza (Leguminosae, Caesalpinioideae, mimosoid clade)

Recent phylogenomic analyses of 997 nuclear genes support the long-held view that the genus Entada is congeneric with Elephantorrhiza. Entada is resolved as monophyletic only if the genus Elephantorrhiza is subsumed within it. The two genera were distinguished solely by relatively minor differences in the mode of dehiscence of the fruits (a craspedium separating into one-seeded endocarp segments in Entada versus a craspedium with the whole fruit valve breaking away from the persistent replum in Elephantorrhiza) and the craspedial fruit type itself provides a shared synapomorphy for the re-circumscribed Entada. Here, we provide a synopsis of Entada, including 11 new combinations in total, for the eight species, one subspecies and one variety previously placed in Elephantorrhiza, as well as a new combination for a subspecies of Entada rheedei Spreng. not previously dealt with when Entada pursaetha DC. was placed in synonymy. These new combinations are: Entada burkei (Benth.) S.A. O’Donnell & G.P. Lewis, comb. nov.; Entada elephantina (Burch.) S.A. O’Donnell & G.P. Lewis, comb. nov.; Entada goetzei (Harms) S.A. O’Donnell & G.P. Lewis, comb. nov.; Entada goetzei subsp. lata (Brenan & Brummitt) S.A. O’Donnell & G.P. Lewis, comb. nov.; Entada obliqua (Burtt Davy) S.A. O’Donnell & G.P. Lewis, comb. nov.; Entada praetermissa (J.H. Ross) S.A. O’Donnell & G.P. Lewis, comb. nov.; Entada rangei (Harms) S.A. O’Donnell & G.P. Lewis, comb. nov.; Entada rheedei subsp. sinohimalensis (Grierson & D.G. Long) S.A. O’Donnell & G.P. Lewis, comb. nov.; Entada schinziana (Dinter) S.A. O’Donnell & G.P. Lewis, comb. nov.; Entada woodii (E. Phillips) S.A. O’Donnell & G.P. Lewis, comb. nov.; and Entada woodii var. pubescens (E. Phillips) S.A. O’Donnell & G.P. Lewis, comb. nov. We provide a revised circumscription of the genus Entada which now comprises 40 species distributed pantropically, with the greatest diversity of species in tropical Africa. We present a complete taxonomic synopsis, including a map showing the global distribution of the genus and photographs showing variation amongst species in habit, foliage, flowers and fruits. A short discussion about extrafloral nectaries, mainly observed in the Madagascan species, is presented

Charm and Bottom Semileptonic Decays

We review the present status of theoretical attempts to calculate the semileptonic charm and bottom decays and then present a calculation of these decays in the light--front frame at the kinematic point $q^2=0$. This allows us to evaluate the form factors at the same value of $q^2$, even though the allowed kinematic ranges for charm and bottom decays are very different. Also, at this kinematic point the decay is given in terms of only one form factor $A_{0}(0)$. For the ratio of the decay rates given by the E653 collaboration we show that the determination of the ratio of the Cabibbo--Kobayashi--Maskawa (CKM) matrix elements is consistent with that obtained from the unitarity constraint. At present, though, the unitarity method still has greater accuracy. Since comparisons of the semileptonic decays into $\rho$ and either electrons or muons will be available soon from the E791 Fermilab experiment, we also look at the massive muon case. We show that for a range of $q^2$ the $SU(3)_F$ symmetry breaking is small even though the contributions of the various helicity amplitudes becomes more complicated. For $B$ decays, the decay $B \rightarrow K^{*} \ell \bar{\ell}$ at $q^2=0$ involves an extra form factor coming from the photon contribution and so is not amenable to the same kind of analysis, leaving only the decay $B \rightarrow K^{*}\nu \bar{\nu}$ as a possibility. As the mass of the decaying particle increases we note that the $SU(3)$ symmetry becomes badly broken at $q^2=0$.Comment: Latex, 19 pages, two figures are attached, a minor change in the manuscript related to thi