281 research outputs found
Implications of the Recommendations of the Expert Panel on Federal Support to Research and Development
Canada lags behind many of its First World counterparts when it comes to business innovation, and urgently needs to improve its performance if it is to remain competitive and attractive to investment. The Expert Panel Report on Federal Support to Research and Development has recommended several policy initiatives that governments need to enact to close the gap. This paper reviews all six major recommendations made by the Expert Panel and provides thorough assessments of each, with ample consideration given to their implications for the private sector. The two most promising are: (1) the consolidation of research and development spending programs at the federal level and (2) the adoption of smart procurement as a means of spurring innovation in the non-government sector. While some of the other recommendations need refinement and raise concerns about their impact on the economy, the message for government and business is clear: the former can and should facilitate Canadian business innovation by removing tax and regulatory burdens and facilitating better public-private cooperation, while the latter must make innovation a major part of corporate culture. This paper explains the consequences of the Panelβs recommendations for both sectors, identifies the deficiencies, and offers clear-eyed guidance for ameliorating them
Oxytocin regulates the expression of aquaporin 5 in the late-pregnant rat uterus
Aquaporins (AQPs) are integral membrane channels responsible for the transport of water across a cell membrane. Based on reports that AQPs are present and
accumulate in the female reproductive tract late in pregnancy, our aim was to study the expression of AQP isoforms (AQP1, 2, 3, 5, 8, and 9) at the end of pregnancy in rat in order to determine if they play a role in parturition. Reverse-transcriptase PCR revealed that specific Aqp mRNAs were detectable in the myometrium of nonpregnant and late-pregnancy (Days 18, 20, 21, and 22 of pregnancy) rat uteri. The expression of Aqp5 mRNA and protein were most pronounced on Days 18-21, and were dramatically decreased on Day 22 of pregnancy. In contrast, a significant increase was found in the level of Aqp5 transcript in whole-blood samples on the last day of pregnancy. The effect of oxytocin on myometrial Aqp5 expression in an organ bath was also investigated. The level of Aqp5 mRNA significantly decreased 5 min after oxytocin (10-8 M) administration, similarly to its profile on the day of delivery; this effect was sensitive to the oxytocin antagonist atosiban. The vasopressin analog desmopressin (3.7x10-8 M), on the other hand, did not alter the expression of Aqp5, but did increased the amount of Aqp2 mRNA, an effect that was atosiban-resistant. These results lead us to propose that oxytocin selectively influences the expression of Aqp5 at the end of pregnancy, and may participate in events that lead to parturition in the rat. The sudden increase of AQP5 in the blood on the last dayof pregnancymayserve as a marker that indicates the initiation of delivery
Possible origins of macroscopic left-right asymmetry in organisms
I consider the microscopic mechanisms by which a particular left-right (L/R)
asymmetry is generated at the organism level from the microscopic handedness of
cytoskeletal molecules. In light of a fundamental symmetry principle, the
typical pattern-formation mechanisms of diffusion plus regulation cannot
implement the "right-hand rule"; at the microscopic level, the cell's
cytoskeleton of chiral filaments seems always to be involved, usually in
collective states driven by polymerization forces or molecular motors. It seems
particularly easy for handedness to emerge in a shear or rotation in the
background of an effectively two-dimensional system, such as the cell membrane
or a layer of cells, as this requires no pre-existing axis apart from the layer
normal. I detail a scenario involving actin/myosin layers in snails and in C.
elegans, and also one about the microtubule layer in plant cells. I also survey
the other examples that I am aware of, such as the emergence of handedness such
as the emergence of handedness in neurons, in eukaryote cell motility, and in
non-flagellated bacteria.Comment: 42 pages, 6 figures, resubmitted to J. Stat. Phys. special issue.
Major rewrite, rearranged sections/subsections, new Fig 3 + 6, new physics in
Sec 2.4 and 3.4.1, added Sec 5 and subsections of Sec
More lead stars
The standard model for the operation of the s-process in asymptotic giant
branch (AGB) stars predicts that low-metallicity ([Fe/H] <= -1) AGB stars
should exhibit large overabundances of Pb and Bi as compared to other
s-elements. Eight CH stars (with [Fe/H] ranging from -1.5 to -2.5) are studied
in the present paper using high-resolution spectra (R = lambda/Delta lambda =
135 000), and five of them appear to be enriched in lead (with [Pb/Ce] ~ 0.7).
Abundances of heavy elements in these `lead stars' (defined as stars enriched
in s-elements and with [Pb/hs] >= 1, hs being any of Ba, La or Ce) are
consistent with the predictions for the s-process operating in low-metallicity
AGB stars as a consequence of the `partial mixing' of protons below the
convective hydrogen envelope. Two among the studied stars (HD 189711 and V Ari)
add to a growing number of low-metallicity stars which do not conform to these
predictions, however. Variations on the canonical proton-mixing scenario for
the operation of the s-process in low-metallicity stars, that could account for
these discrepant stars, are briefly discussed.Comment: 9 pages, 6 figures, accepted for publication in Astronomy &
Astrophysics. Also available at http://www-astro.ulb.ac.be/Html/ps.html#PR
The design and testing of a dual fiber textile matrix for accelerating surface hemostasis
The standard treatment for severe traumatic injury is frequently compression and application of gauze dressing to the site of hemorrhage. However, while able to rapidly absorb pools of shed blood, gauze fails to provide strong surface (topical) hemostasis. The result can be excess hemorrhage-related morbidity and mortality. We hypothesized that cost-effective materials (based on widespread availability of bulk fibers for other commercial uses) could be designed based on fundamental hemostatic principles to partially emulate the wicking properties of gauze while concurrently stimulating superior hemostasis. A panel of readily available textile fibers was screened for the ability to activate platelets and the intrinsic coagulation cascade in vitro. Type E continuous filament glass and a specialty rayon fiber were identified from the material panel as accelerators of hemostatic reactions and were custom woven to produce a dual fiber textile bandage. The glass component strongly activated platelets while the specialty rayon agglutinated red blood cells. In comparison with gauze in vitro, the dual fiber textile significantly enhanced the rate of thrombin generation, clot generation as measured by thromboelastography, adhesive protein adsorption and cellular attachment and activation. These results indicate that hemostatic textiles can be designed that mimic gauze in form but surpass gauze in ability to accelerate hemostatic reactions
Biological flora of Central europe: Baldellia ranunculoides (Alismataceae)
Baldellia ranunculoides (L.) Parl. (Alismataceae) is a taxonomically problematic aquatic plant with an historically ill-defined distribution and global conservation status. This paper finds morphological, ecological and molecular evidence for two distinct taxa, probably best described as subspecies: (1) B. ranunculoides subsp. ranunculoides and (2) B. ranunculoides subsp. repens and provides detailed distribution data on their overlapping range, in different habitats, across the cool, high rainfall areas of western Europe and west Mediterranean. The two subspecies are amongst the relatively large number of threatened European and north Africa aquatic plants and this paper provides a systematic review of their relative conservation pressures and management needs, with particular emphasis on the status of both taxa in central Europe. Other observations indicate probable evolutionary relationships within B. ranunculoides s.l. and its associated taxa and the review points out where these and other research topics could potentially be pursued
The Hamburg/ESO R-process Enhanced Star survey (HERES) III. HE 0338-3945 and the formation of the r+s stars
We have derived abundances of 33 elements and upper limits for 6 additional
elements for the metal-poor ([Fe/H] = -2.42) turn-off star HE 0338-3945 from
high-quality VLT-UVES spectra. The star is heavily enriched, by about a factor
of 100 relative to iron and the Sun, in the heavy s-elements (Ba, La, ..). It
is also heavily enriched in Eu, which is generally considered an r-element, and
in other similar elements. It is less enriched, by about a factor of 10, in the
lighter s-elements (Sr, Y and Zr). C is also strongly enhanced and, to a
somewhat lesser degree, N and O. These abundance estimates are subject to
severe uncertainties due to NLTE and thermal inhomogeneities which are not
taken into detailed consideration. However, an interesting result, which is
most probably robust in spite of these uncertainties, emerges: the abundances
derived for this star are very similar to those of other stars with an overall
enhancement of all elements beyond the iron peak.
We have defined criteria for this class of stars, r+s stars, and discuss nine
different scenarios to explain their origin. None of these explanations is
found to be entirely convincing. The most plausible hypotheses involve a binary
system in which the primary component goes through its giant branch and
asymptotic giant branch phases and produces CNO and s-elements which are dumped
onto the observed star. Whether the r-element Eu is produced by supernovae
before the star was formed (perhaps triggering the formation of a low-mass
binary), by a companion as it explodes as a supernova (possibly triggered by
mass transfer), or whether it is possibly produced in a high-neutron-density
version of the s-process is still unclear. Several suggestions are made on how
to clarify this situation.Comment: Accepted for A&A; 22 pages, 9 figures, 2 tables. Table 2 is in
electronic form and available at http://www.astro.uu.se/~karin/table2.dat
with description at http://www.astro.uu.se/~karin/jonsellReadMe
Molecular Motor Proteins and Amyotrophic Lateral Sclerosis
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder affecting motor neurons in the brain, brainstem and spinal cord, which is characterized by motor dysfunction, muscle dystrophy and progressive paralysis. Both inherited and sporadic forms of ALS share common pathological features, however, the initial trigger of neurodegeneration remains unknown. Motor neurons are uniquely targeted by ubiquitously expressed proteins in ALS but the reason for this selectively vulnerability is unclear. However motor neurons have unique characteristics such as very long axons, large cell bodies and high energetic metabolism, therefore placing high demands on cellular transport processes. Defects in cellular trafficking are now widely reported in ALS, including dysfunction to the molecular motors dynein and kinesin. Abnormalities to dynein in particular are linked to ALS, and defects in dynein-mediated axonal transport processes have been reported as one of the earliest pathologies in transgenic SOD1 mice. Furthermore, dynein is very highly expressed in neurons and neurons are particularly sensitive to dynein dysfunction. Hence, unravelling cellular transport processes mediated by molecular motor proteins may help shed light on motor neuron loss in ALS
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