Coherent x-ray generation at 2.7nm using 25fs laser pulses

We demonstrate for the first time that coherent soft-x-ray pulses at wavelengths of 2.7nm can be generated using 25fs driving pulses. High-order harmonic generation in He is used to produce the femtosecond x-ray harmonics, which exhibit discrete individual orders up to 221, followed by a continuum of unresolved harmonics which extend up to at least the 299th order, corresponding to a wavelength of 2.7nm, or an energy of 450eV. The large ionization potential of He, together with the ultrashort nature of the driving field, results in this dramatic extension of the harmonic plateau, by approximately 200 orders more than has been observed previously. We also obtain excellent agreement with theoretical predictions. © 1998 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87449/2/296_1.pd

An Extension of the Direct Method for Verifying Programs

A direct method based on a finite set of path formulas which describe the input-output relations of a given program can be used to verify programs containing no overlapping loops. One major difficulty in verifying programs with overlapping loops using the above method is that too many path formulas (possibly infinite) needed to be considered. In this paper, we circumvent the above difficulty by applying the concept of modularity. The idea is to divide a program with overlapping loops into several small modules so that each module contains no overlapping loop. This can always be achieved if the program is in structured form. Then the path formulas will be derived for each module. By combining the path formulas for the modules, one can further obtain the path formulas for the given program and then use them to verify the program

Tricin Biosynthesis and Bioengineering

Tricin (3', 5'-dimethoxyflavone) is a specialized metabolite which not only confers stress tolerance and involves in defense responses in plants but also represents a promising nutraceutical. Tricin-type metabolites are widely present as soluble tricin O-glycosides and tricin-oligolignols in all grass species examined, but only show patchy occurrences in unrelated lineages in dicots. More strikingly, tricin is a lignin monomer in grasses and several other angiosperm species, representing one of the “non-monolignol” lignin monomers identified in nature. The unique biological functions of tricin especially as a lignin monomer have driven the identification and characterization of tricin biosynthetic enzymes in the past decade. This review summarizes the current understanding of tricin biosynthetic pathway in grasses and tricin-accumulating dicots. The characterized and potential enzymes involved in tricin biosynthesis are highlighted along with discussion on the debatable and uncharacterized steps. Finally, current developments of bioengineering on manipulating tricin biosynthesis toward the generation of functional food as well as modifications of lignin for improving biorefinery applications are summarized

Rapid and accurate broadband absorption cross-section measurement of human bodies in a reverberation chamber

A measurement methodology for polarization and angle of incidence averaged electromagnetic absorption cross-section using a reverberation chamber is presented. The method is optimized for simultaneous rapid and accurate determination of average absorption cross-section over the frequency range 1–15 GHz, making it suitable for use in human absorption and exposure studies. The typical measurement time of the subject is about 8 min with a corresponding statistical uncertainty of about 3% in the measured absorption cross-section. The method is validated by comparing measurements on a spherical phantom with Mie series calculations. The efficacy of the method is demonstrated with measurements of the posture dependence of the absorption cross-section of a human subject and an investigation of the effects of clothing on the measured absorption which are important considerations for the practical design of experiments for studies on human subjects

Analysis of retinal cell development in chick embryo by immunohistochemistry and in ovo electroporation techniques

<p>Abstract</p> <p>Background</p> <p>Retinal cell development has been extensively investigated; however, the current knowledge of dynamic morphological and molecular changes is not yet complete.</p> <p>Results</p> <p>This study was aimed at revealing the dynamic morphological and molecular changes in retinal cell development during the embryonic stages using a new method of targeted retinal injection, <it>in ovo </it>electroporation, and immunohistochemistry techniques. A plasmid DNA that expresses the green fluorescent protein (GFP) as a marker was delivered into the sub-retinal space to transfect the chick retinal stem/progenitor cells at embryonic day 3 (E3) or E4 with the aid of pulses of electric current. The transfected retinal tissues were analyzed at various stages during chick development from near the start of neurogenesis at E4 to near the end of neurogenesis at E18. The expression of GFP allowed for clear visualization of cell morphologies and retinal laminar locations for the indication of retinal cell identity. Immunohistochemistry using cell type-specific markers (e.g., Visinin, Xap-1, Lim1+2, Pkcα, NeuN, Pax6, Brn3a, Vimentin, etc.) allowed further confirmation of retinal cell types. The composition of retinal cell types was then determined over time by counting the number of GFP-expressing cells observed with morphological characteristics specific to the various retinal cell types.</p> <p>Conclusion</p> <p>The new method of retinal injection and electroporation at E3 - E4 allows the visualization of all retinal cell types, including the late-born neurons, e.g., bipolar cells at a level of single cells, which has been difficult with a conventional method with injection and electroporation at E1.5. Based on data collected from analyses of cell morphology, laminar locations in the retina, immunohistochemistry, and cell counts of GFP-expressing cells, the time-line and dynamic morphological and molecular changes of retinal cell development were determined. These data provide more complete information on retinal cell development, and they can serve as a reference for the investigations in normal retinal development and diseases.</p

Oedema extension distance in intracerebral haemorrhage: Association with baseline characteristics and long-term outcome

Introduction: Oedema extension distance is a derived parameter that may reduce sample size requirements to demonstrate reduction in perihaematomal oedema in early phase acute intracerebral haemorrhage trials. We aimed to identify baseline predictors of oedema extension distance and its association with clinical outcomes. Patients and methods: Using Virtual International Stroke Trials Archive-Intracerebral Haemorrhage, first Intensive Blood Pressure Reduction in Acute Cerebral Hemorrhage Trial, and Minimally Invasive Surgery and rtPA for Intracerebral Hemorrhage Evacuation II datasets, we calculated oedema extension distance at baseline and at 72 h measured using computed tomography. Using linear regression, we tested for associations between baseline characteristics and oedema extension distance at 72 h. Ordinal regression (underlying assumptions validated) was used to test for associations between oedema extension distance at baseline and 72 h and oedema extension distance change between baseline and 72 h, and modified Rankin scale scores at 90 days, adjusted for baseline and 72 h prognostic factors. Results: There were 1028 intracerebral haemorrhage cases with outcome data for analyses. Mean (standard deviation, SD) oedema extension distance at 72 h was 0.54 (0.26) cm, and mean oedema extension distance difference from baseline (EED72–0) was 0.24 (0.18) cm. Oedema extension distance at 72 h was greater with increasing baseline haematoma volume and baseline oedema extension distance. Increasing age, lobar haemorrhage, and intraventricular haemorrhage were independently associated with EED72–0. In multifactorial ordinal regression analysis, EED72–0 was associated with worse modified Rankin scale scores at 90 days (odds ratio 1.96, 95% confidence interval 1.00–3.82). Discussion: Increase in oedema extension distance over 72 h is independently associated with decreasing functional outcome at 90 days. Oedema extension distance may be a useful surrogate outcome measure in early phase trials of anti-oedema or anti-inflammatory treatments in intracerebral haemorrhage

On the Long-Term Hydroclimatic Sustainability of Perennial Bioenergy Crop Expansion over the United States

Large-scale cultivation of perennial bioenergy crops (e.g., miscanthus and switchgrass) offers unique opportunities to mitigate climate change through avoided fossil fuel use and associated greenhouse gas reduction. Although conversion of existing agriculturally intensive lands (e.g., maize and soy) to perennial bioenergy cropping systems has been shown to reduce near-surface temperatures, unintended consequences on natural water resources via depletion of soil moisture may offset these benefits. The hydroclimatic impacts associated with perennial bioenergy crop expansion over the contiguous United States are quantified using the Weather Research and Forecasting Model dynamically coupled to a land surface model (LSM). A suite of continuous (2000–09) medium-range resolution (20-km grid spacing) ensemble-based simulations is conducted using seasonally evolving biophysical representation of perennial bioenergy cropping systems within the LSM based on observational data. Deployment is carried out only over suitable abandoned and degraded farmlands to avoid competition with existing food cropping systems. Results show that near-surface cooling (locally, up to 5°C) is greatest during the growing season over portions of the central United States. For some regions, principal impacts are restricted to a reduction in near-surface temperature (e.g., eastern portions of the United States), whereas for other regions deployment leads to soil moisture reduction in excess of 0.15–0.2 m3 m−3 during the simulated 10-yr period (e.g., western Great Plains). This reduction (~25%–30% of available soil moisture) manifests as a progressively decreasing trend over time. The large-scale focus of this research demonstrates the long-term hydroclimatic sustainability of large-scale deployment of perennial bioenergy crops across the continental United States, revealing potential hot spots of suitable deployment and regions to avoid

A genetic variation map for chicken with 2.8 million single-nucleotide polymorphisms

We describe a genetic variation map for the chicken genome containing 2.8 million single-nucleotide polymorphisms ( SNPs). This map is based on a comparison of the sequences of three domestic chicken breeds ( a broiler, a layer and a Chinese silkie) with that of their wild ancestor, red jungle fowl. Subsequent experiments indicate that at least 90% of the variant sites are true SNPs, and at least 70% are common SNPs that segregate in many domestic breeds. Mean nucleotide diversity is about five SNPs per kilobase for almost every possible comparison between red jungle fowl and domestic lines, between two different domestic lines, and within domestic lines - in contrast to the notion that domestic animals are highly inbred relative to their wild ancestors. In fact, most of the SNPs originated before domestication, and there is little evidence of selective sweeps for adaptive alleles on length scales greater than 100 kilobases