Automatic holographic droplet analysis for liquid fuel sprays

The basic scheme for automated holographic analysis involves an optical system for reconstruction of the three dimensional real image of the droplet field, a spatial scanning system to transport a digitizing X-y image sensor through the real image, and processing algorithms for droplet recognition which establish the droplet sizes and positions. The hardware for system demonstrated includes the expanded and collimated beam from a 5 mW helium-neon laser for hologram reconstruction, an imaging lens for magnification of the real image field, and a video camera and digitizer providing 512-by-512 pixel resolution with 8-bit digitization. A mechanical stage is used to scan the hologram in three dimensional space, maintaining constant image magnification. A test droplet hologram is used for development and testing of the image processing algorithms

Carrier dynamics and coherent acoustic phonons in nitride heterostructures

We model generation and propagation of coherent acoustic phonons in piezoelectric InGaN/GaN multi-quantum wells embedded in a \textit{pin} diode structure and compute the time resolved reflectivity signal in simulated pump-probe experiments. Carriers are created in the InGaN wells by ultrafast pumping below the GaN band gap and the dynamics of the photoexcited carriers is treated in a Boltzmann equation framework. Coherent acoustic phonons are generated in the quantum well via both deformation potential electron-phonon and piezoelectric electron-phonon interaction with photogenerated carriers, with the latter mechanism being the dominant one. Coherent longitudinal acoustic phonons propagate into the structure at the sound speed modifying the optical properties and giving rise to a giant oscillatory differential reflectivity signal. We demonstrate that coherent optical control of the differential reflectivity can be achieved using a delayed control pulse.Comment: 14 pages, 11 figure

Propagating Coherent Acoustic Phonon Wavepackets in InMnAs/GaSb

We observe pronounced oscillations in the differential reflectivity of a ferromagnetic InMnAs/GaSb heterostructure using two-color pump-probe spectroscopy. Although originally thought to be associated with the ferromagnetism, our studies show that the oscillations instead result from changes in the position and frequency-dependent dielectric function due to the generation of coherent acoustic phonons in the ferromagnetic InMnAs layer and their subsequent propagation into the GaSb. Our theory accurately predicts the experimentally measured oscillation period and decay time as a function of probe wavelength.Comment: 4 pages, 4 figure

The radical character of the acenes: A density matrix renormalization group study

We present a detailed investigation of the acene series using high-level wavefunction theory. Our ab-initio Density Matrix Renormalization Group algorithm has enabled us to carry out Complete Active Space calculations on the acenes from napthalene to dodecacene correlating the full pi-valence space. While we find that the ground-state is a singlet for all chain-lengths, examination of several measures of radical character, including the natural orbitals, effective number of unpaired electrons, and various correlation functions, suggests that the longer acene ground-states are polyradical in nature.Comment: 10 pages, 8 figures, supplementary material, to be published in J. Chem. Phys. 127, 200

Quality of life among adults following bariatric and body contouring surgery: a systematic review.

Background: Weight loss following bariatric surgery is associated with significant improvements in obesity-related comorbidities, body satisfaction and psychosocial outcomes, at least in the short term. However, in the context of extreme weight loss, body image and appearance may worsen again because the “excess” or “loose” skin can lead to both functional and profound dissatisfaction with appearance. These concerns have led to an increasing uptake of post-bariatric surgery, “body-contouring” procedures but the implications for quality of life (QoL) have not been thoroughly considered. Objective/purpose: The objective was to identify the best available evidence regarding the QoL outcomes for adults following bariatric and body contouring surgery. Inclusion criteria Types of participants: The review considered studies involving people aged 18 years and beyond who underwent bariatric surgery and body contouring surgery. Types of interventions: The review considered studies that evaluated bariatric surgery as well as body contouring surgery. Types of studies: The review considered both experimental and epidemiological study designs. Outcomes: The primary outcomes were QoL as measured by validated tools at less than two years, two to five years and more than five years following body contouring surgery. The secondary outcomes were adverse events, unsatisfactory aesthetic appearance and weight gain. Search strategy: Six databases were searched, including Cochrane Central, MEDLINE, Embase, Web of Science, PsycINFO and CINAHL. Studies published from 1954 to 2014 were considered. Additional searches for unpublished studies were undertaken in BIOSIS citation index, Register of Current Controlled Trials and Global Health Observatory. Methodological quality: The methodological quality of eligible studies was assessed independently by two reviewers using the Joanna Briggs Institute quality assessment tool. Data extraction: Data extraction from the included studies was undertaken and summarized independently by two reviewers using the standardized Joanna Briggs Institute data extraction tool. Data synthesis: Studies were too heterogeneous and could not be pooled in statistical meta-analysis. Therefore, the data results are presented as a narrative summary in relation to the outcomes of interest. Results: Nine quantitative studies (four comparable cohort studies, including two group design and two four-group designs and five descriptive or case-series studies) were included in the review. The included studies reported significant clinical improvements in appearance, wellbeing and QoL. These included primary outcomes pointing to body image satisfaction, improved self-esteem and confidence, improved physical function/pain and improved social function. The secondary outcomes were related to adverse events in the early postoperative period and reported wound healing problems, including seromas, partial necrosis, dehiscence, hematoma and anemia because of blood loss. Also, some data sets shed light on appearance-related distress and body dysphoria post surgery associated with visible scars and contour deformities. Conclusion: Body contouring surgery has been shown to have positive benefits, especially in relation to improved wellbeing, function and QoL. However, adjustment to changing body image following body contouring is both challenging and empowering and seems to be a transitional process

The calpastatin-derived calpain inhibitor CP1B reduces mRNA expression of matrix metalloproteinase-2 and-9 and invasion by leukemic THP-1 cells

The ubiquitous proteases μ- and m-calpain are Ca2+-dependent cysteine endopeptidases. Besides involvement in a variety of physio(patho)logical processes, recent studies suggest a pivotal role of calpains in differentiation of hematopoietic cells and tumor cell invasion. However, the precise actions of calpains and their endogenous inhibitor, calpastatin, in these processes are only partially understood. Here we have studied the role of the calpain/calpastatin system in the invasion of leukemic cells under basal and differentiationstimulating conditions. To further differentiate the human leukaemic cell line THP-1 (monocytic), the cells were treated for 24 hours with the differentiationstimulating reagents phorbol 12-myristate 13-acetate (PMA) and dimethyl sulfoxide (DMSO). Macrophage and granulocytelike differentiation was confirmed by induction of vimentin expression as well as by microscopic and fluorescence assisted cytometric analysis. Extracellular matrix (ECM) invasion of both the basal and differentiation stimulated cells in a Matrigel assay was inhibited by preincubation of the cells with the specific calpain inhibitor CP1B for 24 hours. Inhibition of invasiveness correlated with decreased mRNA expression and secretion of the matrix metalloproteinases MMP-2 and MMP-9. In contrast, addition of CP1B only during the invasion process did neither influence transmigration nor MMP release. This is the first report showing that the calpain/calpastatin system mediates MMPmRNA expression of the leukemic THP-1 cells and as a consequence their invasiveness

Human cytomegalovirus: taking the strain

In celebrating the 60th anniversary of the first isolation of human cytomegalovirus (HCMV), we reflect on the merits and limitations of the viral strains currently being used to develop urgently needed treatments. HCMV research has been dependent for decades on the high-passage strains AD169 and Towne, heavily exploiting their capacity to replicate efficiently in fibroblasts. However, the genetic integrity of these strains is so severely compromised that great caution needs to be exercised when considering their past and future use. It is now evident that wild-type HCMV strains are not readily propagated in vitro. HCMV mutants are rapidly selected during isolation in fibroblasts, reproducibly affecting gene RL13, the UL128 locus (which includes genes UL128, UL130 and UL131A) and often the UL/b′ region. As a result, the virus becomes less cell associated, altered in tropism and less pathogenic. This problem is not restricted to high-passage strains, as even low-passage strains can harbour biologically significant mutations. Cloning and manipulation of the HCMV genome as a bacterial artificial chromosome (BAC) offers a means of working with stable, genetically defined strains. To this end, the low-passage strain Merlin genome was cloned as a BAC and sequentially repaired to match the viral sequence in the original clinical sample from which Merlin was derived. Restoration of UL128L to wild type was detrimental to growth in fibroblasts, whereas restoration of RL13 impaired growth in all cell types tested. Stable propagation of phenotypically wild-type virus could be achieved only by placing both regions under conditional expression. In addition to the development of these tools, the Merlin transcriptome and proteome have been characterized in unparalleled detail. Although Merlin may be representative of the clinical agent, high-throughput whole-genome deep sequencing studies have highlighted the remarkable high level of interstrain variation present in circulating virus. There is a need to develop systems capable of addressing the significance of this diversity, free from the confounding effects of genetic changes associated with in vitro adaptation. The generation of a set of BAC clones, each containing the genome of a different HCMV strain repaired to match the sequence in the clinical sample, would provide a pathway to address the biological and clinical effects of natural variation in wild-type HCMV

Generalized Involution Models for Wreath Products

We prove that if a finite group $H$ has a generalized involution model, as defined by Bump and Ginzburg, then the wreath product $H \wr S_n$ also has a generalized involution model. This extends the work of Baddeley concerning involution models for wreath products. As an application, we construct a Gelfand model for wreath products of the form $A \wr S_n$ with $A$ abelian, and give an alternate proof of a recent result due to Adin, Postnikov, and Roichman describing a particularly elegant Gelfand model for the wreath product \ZZ_r \wr S_n. We conclude by discussing some notable properties of this representation and its decomposition into irreducible constituents, proving a conjecture of Adin, Roichman, and Postnikov's.Comment: 29 page

Resonant Coherent Phonon Spectroscopy of Single-Walled Carbon Nanotubes

Using femtosecond pump-probe spectroscopy with pulse shaping techniques, one can generate and detect coherent phonons in chirality-specific semiconducting single-walled carbon nanotubes. The signals are resonantly enhanced when the pump photon energy coincides with an interband exciton resonance, and analysis of such data provides a wealth of information on the chirality-dependence of light absorption, phonon generation, and phonon-induced band structure modulations. To explain our experimental results, we have developed a microscopic theory for the generation and detection of coherent phonons in single-walled carbon nanotubes using a tight-binding model for the electronic states and a valence force field model for the phonons. We find that the coherent phonon amplitudes satisfy a driven oscillator equation with the driving term depending on photoexcited carrier density. We compared our theoretical results with experimental results on mod 2 nanotubes and found that our model provides satisfactory overall trends in the relative strengths of the coherent phonon signal both within and between different mod 2 families. We also find that the coherent phonon intensities are considerably weaker in mod 1 nanotubes in comparison with mod~2 nanotubes, which is also in excellent agreement with experiment.Comment: 21 pages, 22 figure