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Background: Procedural analgesia is essential for burn-injured patients. Ketamine is the cornerstone of many procedural analgesia protocols for children as it is safe and effective. However, it requires monitoring and the child may remain sedated for a number of hours. We sought an alternative analgesic option. Methoxyflurane is an inhalational analgesic with rapid onset of action for short term analgesia. There is little literature on the use of this drug in children in South Africa, particularly in burns patients. This paper describes our introduction of methoxyflurane into our procedural analgesia protocols for pain associated with dressing changes for paediatric burns. Methods: We performed a retrospective review of data from the burns database for a two-month period after the addition of methoxyflurane to the paediatric burn outpatient procedural analgesia protocol as the first line analgesia option. Results: Ninety-five children were reviewed in the clinic over the two-month period. Thirty patients did not require analgesia for their dressing changes. Methoxyflurane provided effective analgesia in 49/65 (75%) patients. Conclusion: This study has shown that methoxyflurane is a viable option for analgesia for burns dressing changes in a busy outpatient setting. It is an effective and safe alternative to ketamine. Further research is required into the use of methoxyflurane in other burns settings to clarify predictors of failure, ease of use and possible side effect profiles. The full articles is available at https://doi.org/10.36303/SAJAA.2020.26.5.2311

Stony coral tissue loss disease (SCTLD) is decimating Caribbean corals. Here, through the metatranscriptomic assembly and annotation of two alphaflexivirus-like strains, we provide genomic evidence of filamentous viruses in SCTLD-affected, -exposed, and -unexposed coral colonies. These data will assist in clarifying the roles of viruses in SCTLD.

Erbium-doped gallium nitride (Er:GaN) is a promising gain material for solid-state high-energy lasers operating in the 1.5 μm wavelength window due to the superior optical properties and extremely high thermal conductivity of a GaN host crystal that permit high-power and high-temperature applications. We report the realization of all-crystalline GaN/Er:GaN/GaN embedded waveguide fiber structures using the hydride vapor phase epitaxy growth and re-growth technique, along with chemical–mechanical polishing processes. The Er:GaN core layer possesses an Er doping concentration of [Formula: see text] atoms/cm3, confirmed by secondary ion mass spectrometry measurements. X-ray diffraction measurements confirm, respectively, c-, a-, and m-plane orientations for top/bottom, side, and front/back cross-sectional cladding layers of the fiber structure with good single-crystalline quality. The 1.5 μm Er3+ emission was detected from each surface of the fiber structures via 980 nm resonant excitation. The effect of 1.54 μm light guiding by the fiber structure has been demonstrated. This work laid the foundation toward achieving all-crystalline core-cladding fibers based on GaN wide bandgap semiconductor with potential applications in the harsh environments of high powers, power densities, and temperatures.

Erbium doped GaN (Er:GaN) is a promising candidate as a novel gain medium for solid-state high energy lasers (HELs) due to its superior physical properties over a synthetic garnet such as Nd:YAG. Er:GaN emits in the 1.5 µm region, which is retina-safe and has a high transmission in the air. We report photoluminescence (PL) studies performed on Er:GaN epilayers synthesized by the hydride vapor phase epitaxy (HVPE) technique. The room temperature PL spectra of HVPE grown Er:GaN epilayers resolved as many as 11 and seven emission lines in the 1.5 µm and 1.0 µm wavelength regions, respectively, corresponding to the intra-4f shell transitions between Stark levels from the first (4I13/2) and the second (4I11/2) excited states to the ground state (4I15/2) of Er3+ in GaN. The observed peak positions of these transitions enabled the construction of the detailed energy levels in Er:GaN. The results agree well with those of the calculation based on a crystal field analysis. Precise determination of the detailed energy levels of the Stark levels in the 4I11/2, 4I13/2, and 4I15/5 states is critically important for the realization of HELs based on Er:GaN.

Erbium-doped GaN (Er:GaN) quasi-bulk crystals are emerging as a promising novel gain medium for high energy lasers emitting at the retina-safe wavelength window of 1.5 μm. We report the polarization-resolved photoluminescence (PL) emission spectroscopy studies, which revealed that the pumping efficiency with the excitation polarization parallel to the c-axis of GaN ( E ⇀ | | c ⇀ ) is significantly higher than that with the excitation polarization perpendicular to the c-axis of GaN ( E ⇀ ⊥ c ⇀ ). This phenomenon is a direct consequence of the inherent polar wurtzite GaN lattice, giving rise to a net local field, surrounding each Er ion, along the c-axis of GaN. The temperature dependent behaviors of the PL emission spectra were explained in terms of the Boltzmann population distributions among sublevels within the 4I15/2 ground state and the 4I13/2 first excited state of Er3+ in GaN, thereby providing an improved understanding regarding the origin of the dominant emission lines observed near 1.5 μm. The results suggested that the polarization field in GaN can be exploited to enhance the effective Er excitation cross section by manipulating the polarization of the excitation light source.

The onslaught of foreign antigens carried by spermatozoa into the epididymis, an organ that has not demonstrated immune privilege, a decade or more after the establishment of central immune tolerance presents a unique biological challenge. Historically, the physical confinement of spermatozoa to the epididymal tubule enforced by a tightly interwoven wall of epithelial cells was considered sufficient enough to prevent cross talk between gametes and the immune system and, ultimately, autoimmune destruction. The discovery of an intricate arrangement of mononuclear phagocytes (MPs) comprising dendritic cells and macrophages in the murine epididymis suggests that we may have underestimated the existence of a sophisticated mucosal immune system in the posttesticular environment. This review consolidates our current knowledge of the physiology of MPs in the steady state epididymis and speculates on possible interactions between auto-antigenic spermatozoa, pathogens and the immune system by drawing on what is known about the immune system in the intestinal mucosa. Ultimately, further investigation will provide valuable information regarding the origins of pathologies arising as a result of autoimmune or inflammatory responses in the epididymis, including epididymitis and infertility.

One of the major causes of defective sperm function is oxidative stress, which not only disrupts the integrity of sperm DNA but also limits the fertilizing potential of these cells as a result of collateral damage to proteins and lipids in the sperm plasma membrane. The origins of such oxidative stress appear to involve the sperm mitochondria, which have a tendency to generate high levels of superoxide anion as a prelude to entering the intrinsic apoptotic cascade. Unfortunately, these cells have very little capacity to respond to such an attack because they only possess the first enzyme in the base excision repair (BER) pathway, 8-oxoguanine glycosylase 1 (OGG1). The latter successfully creates an abasic site, but the spermatozoa cannot process the oxidative lesion further because they lack the downstream proteins (APE1, XRCC1) needed to complete the repair process. It is the responsibility of the oocyte to continue the BER pathway prior to initiation of S-phase of the first mitotic division. If a mistake is made by the oocyte at this stage of development, a mutation will be created that will be represented in every cell in the body. Such mechanisms may explain the increase in childhood cancers and other diseases observed in the offspring of males who have suffered oxidative stress in their germ line as a consequence of age, environmental or lifestyle factors. The high prevalence of oxidative DNA damage in the spermatozoa of male infertility patients may have implications for the health of children conceived in vitro and serves as a driver for current research into the origins of free radical generation in the germ line.

Erbium doped gallium nitride (Er:GaN) bulk crystals have emerged as a promising optical gain material for high energy lasers (HELs) operating at the 1.5 μm “retina-safe” spectral region. Among the many designs of HEL gain medium, the core-cladding planar waveguide (PWG) structure is highly desired due to its abilities to provide excellent optical confinement and heat dissipation. We report the realization of a GaN/Er:GaN/GaN core-cladding PWG structure synthesized by hydride vapor phase epitaxy and processed by mechanical and chemical-mechanical polishing. An Er doping concentration of [Er] = 3 × 1019 atoms/cm3 has been attained in the core layer, as confirmed by secondary ion mass spectrometry measurements. A strong 1.54 μm emission line was detected from the structure under 980 nm resonant excitation. It was shown that these PWGs can achieve a 96% optical confinement in the Er:GaN core layer having a thickness of 50 μm and [Er] = 3 × 1019 atoms/cm3. This work represents an important step toward the realization of practical Er:GaN gain medium for retina-safe HEL applications.Erbium doped gallium nitride (Er:GaN) bulk crystals have emerged as a promising optical gain material for high energy lasers (HELs) operating at the 1.5 μm “retina-safe” spectral region. Among the many designs of HEL gain medium, the core-cladding planar waveguide (PWG) structure is highly desired due to its abilities to provide excellent optical confinement and heat dissipation. We report the realization of a GaN/Er:GaN/GaN core-cladding PWG structure synthesized by hydride vapor phase epitaxy and processed by mechanical and chemical-mechanical polishing. An Er doping concentration of [Er] = 3 × 1019 atoms/cm3 has been attained in the core layer, as confirmed by secondary ion mass spectrometry measurements. A strong 1.54 μm emission line was detected from the structure under 980 nm resonant excitation. It was shown that these PWGs can achieve a 96% optical confinement in the Er:GaN core layer having a thickness of 50 μm and [Er] = 3 × 1019 atoms/cm3. This work represents an important step toward the real...

The discovery of a truncated base excision repair pathway in human spermatozoa mediated by OGG1 has raised questions regarding the effect of mutations in critical DNA repair genes on the integrity of the paternal genome. The senescence-accelerated mouse prone 8 (SAMP8) is a mouse model containing a suite of naturally occurring mutations resulting in an accelerated senescence phenotype largely mediated by oxidative stress, which is further enhanced by a mutation in theOgg1gene, greatly reducing the ability of the enzyme to excise 8-hydroxy,2′-deoxyguanosine (8OHdG) adducts. An analysis of the reproductive phenotype of the SAMP8 males revealed a high level of DNA damage in caudal epididymal spermatozoa as measured by the alkaline Comet assay. Furthermore, these lesions were confirmed to be oxidative in nature, as demonstrated by significant increases in 8OHdG adduct formation in the SAMP8 testicular tissue (PPP2O2and Fe2+), the SAMP8 spermatozoa demonstrated a highly increased susceptibility to formation of 8OHdG adducts compared with the controls (P

The NPDGamma experiment measures the parity-violating (PV) gamma asymmetry from polarized cold neutrons captured on protons at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL). The (PV) neutron spin asymmetry A γ of photons from polarized cold neutron capture on protons is proportional to the ΔI=1 long range weak meson coupling $h_{\pi }^{1}$ between nucleons in the hadronic weak interaction (HWI). Liquid para-hydrogen production data taking concluded in April 2014 and once the background aluminum asymmetry measurements are complete, the PV asymmetry A γ can be extracted. Preliminary results of the analysis of A γ are presented.

The NPDGamma collaboration is performing a measurement of the very small parity-violating asymmetry in the angular distribution of the 2.2 MeV γ - rays from the capture of polarized cold neutrons on protons ( A γ ) . The estimated size of A γ is 5 × 10 − 8 , and the measured asymmetry is proportional to the neutron polarization upon capture. Since the interaction of polarized neutrons with one of the two hydrogen molecular states (orthohydrogen) can lead to neutron spin-flip scattering, it is essential that the hydrogen in the target is mostly in the molecular state that will not depolarize the neutrons ( ≥ 99.8 % parahydrogen). For that purpose, in the first stage of the NPDGamma experiment at the Los Alamos Neutron Science Center (LANSCE), we operated a 16-l liquid hydrogen target, which was filled in two different occasions. The parahydrogen fraction in the target was accurately determined in situ by relative neutron transmission measurements. The result of these measurements indicate that the fraction of parahydrogen in equilibrium was 0.9998 ± 0.0002 in the first data taking run and 0.9956 ± 0.0002 in the second. We describe the parahydrogen monitor system, relevant aspects of the hydrogen target, and the procedure to determine the fraction of parahydrogen in the target. Also assuming thermal equilibrium of the target, we extract the scattering cross-section for neutrons on parahydrogen.

The NPDGamma collaboration has recently completed the first phase of a measurement to determine the size of the weak nucleon–nucleon interaction from cold neutron capture on a liquid hydrogen target. In the framework of the nearly 30 year old DDH model [B. Desplanques, J.F. Donoghue, B.R. Holstein, Annals of Physics 124 (1980) 449], the measured process is explained in terms of the weak pion–nucleon coupling, while the framework of modern effective field theory parameterizes the measured process in terms of the S 1 3 - P 1 3 , long range transition (essentially the Danilov parameter ρ t ) [S.L. Zhu et al., Nuclear Physics A 748 (2005) 435; C.-P. Liu, Phys. Rev. C 75 (2007) 065501]. The couplings in terms of either model are directly proportional to the parity violating up-down asymmetry in the angular distribution of gamma rays with respect to the neutron spin direction in the reaction n ⇒ + p → d + γ . The asymmetry has a predicted size of 5 × 10 - 8 and the aim of the NPDGamma collaboration is to measure it to 20%. The first phase of the measurement was completed at the Los Alamos National Laboratory Neutron Science Center Spallation Source with a preliminary result of ( - 1.1 ± 2.1 stat . ± 0.2 sys . ) × 10 - 7 . Here, we report on the measurements and the results obtained so far. The experiment is currently being installed at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory, for the remainder of its run time.

This study reviews the predictive value of maximum oxygen consumption (VO2max) and anaerobic threshold, obtained through cardiopulmonary exercise testing, in calculating peri-operative morbidity and mortality in non-cardiopulmonary thoraco-abdominal surgery. A literature review provided nine studies that investigated either one or both of these two variables across a wide range of surgical procedures. Six of the seven studies that reported sufficiently detailed results on peak oxygen consumption and four of the six studies that reported sufficiently detailed results on anaerobic threshold found them to be significant predictors. We conclude that peak oxygen consumption and possibly anaerobic threshold are valid predictors of peri-operative morbidity and mortality in non-cardiopulmonary thoraco-abdominal surgery. These indicators could potentially provide a means of allocating increased care to high-risk patients.

The mammalian cornea is very nearly transparent to light, a fact that is not obvious from its structure. The explanation lies with the degree of coherence in the scattering of light as it passes through the cornea. This article analyzes this explanation with an approach based on undergraduate electromagnetism concepts.

For the determination of individual errors, methods have been developed which, when applied to a particular kind of mild steel under the usual working conditions, show that at 1300° only about 86% of the total sulphur is liberated as sulphur dioxide. Of the other 14%, the residue retains about 6% and the rest is converted into sulphur trioxide, 3% being absorbed with the sulphur dioxide, 1% escaping absorption, and 4% remaining in the apparatus by condensation. Modifications are suggested by which the total yield could be raised to 92–93%.

A large area polarized 3He neutron spin filter has been developed and tested in long-term operation. The polarizer cells have area 50 cm2 and larger allowing access to a large area neutron beam. Polarization of 3He up to 57 ± 1 % was measured by monitoring the neutron transmission through the 3He. The polarization was maintained over the course of several weeks, but the maximum attainable polarization declined over the course of a year-long run as the cell degraded, possibly due to long-term exposure to the neutron beam at high temperatures. The resulting neutron polarization and transmission are velocity dependent and are optimized for 5 A. Cell construction, polarizer design, performance, and polarimetry are described in this paper.

The modulus squared of a class of wavefunctions defined on phase space is used to define a generalized family of Q or Husimi functions. A parameter lambda specifies orderings in a mapping from the operator psi)(sigma to the corresponding phase space wavefunction, where sigma is a given fiducial vector. The choice lambda = 0 specifies the Weyl mapping and the Q-function so obtained is the usual one when sigma is the vacuum state. More generally, any choice of of lambda in the range (-1,1) corresponds to orderings varying between standard and anti-standard. For all such orderings the generalized Q-functions are non-negative by construction. They are shown to be proportional to expectation of the system state rho with respect to a generalized displaced squeezed state which depends on lambda and position (p,q) in phase space. Thus, when a system has been prepared in the state rho, a generalized Q-function is proportional to the probability of finding it in the generalized squeezed state. Any such Q-function can also be written as the smoothing of the Wigner function for the system state rho by convolution with the Wigner function for the generalized squeezed state.

The NPDGamma γ-ray detector has been built to measure, with high accuracy, the size of the small parity-violating asymmetry in the angular distribution of gamma rays from the capture of polarized cold neutrons by protons. The high cold neutron flux at the Los Alamos Neutron Scattering Center (LANSCE) spallation neutron source and control of systematic errors require the use of current mode detection with vacuum photodiodes and low-noise solid-state preamplifiers. We show that the detector array operates at counting statistics and that the asymmetries due to B4C and (27)Al are zero to with- in 2 × 10(-6) and 7 × 10(-7), respectively. Boron and aluminum are used throughout the experiment. The results presented here are preliminary.

An apparatus for measuring parity-violating asymmetries in gamma-ray emission following polarized cold neutron capture was constructed as a 1/10th scale test of the design for the forthcoming n → + p → d + γ experiment at LANSCE. The elements of the polarized neutron beam, including a polarized 3 He neutron spin filter and a radio frequency neutron spin rotator, are described. Using CsI(Tl) detectors and photodiode current mode readout, measurements were made of asymmetries in gamma-ray emission following neutron capture on 35 Cl , 113 Cd , and 139 La targets. Upper limits on the parity-allowed asymmetry s n ·( k γ × k n ) were set at the level of 7×10 −6 for all three targets. Parity-violating asymmetries s n · k γ were observed in 35 Cl , A γ =(−29.1±6.7)×10 −6 , and 139 La , A γ =(−15.5±7.1)×10 −6 , values consistent with previous measurements.

We have produced 70%–75% 3He polarization by spin-exchange optical pumping in cells ≈100 cm3 in volume. The polarization achieved is consistent with known spin-exchange and spin-relaxation rates, but only when the recently discovered temperature dependence of 3He relaxation is included. Absolute 3He polarization measurements were performed using two different methods in two different laboratories. The results were obtained with either a spectrally narrowed laser or one type of broadband laser. Based on tests of several larger cells at pressures near 1 bar, we find that the power required to reach the same polarization is typically three times lower for the spectrally narrowed laser. This last result indicates that spectrally narrowed lasers will be important for obtaining the highest polarization in large volume neutron spin filters. Polarization in excess of 55% as obtained in cells up to 640 cm3 in volume and 70% polarization is anticipated with available increases in spectrally narrowed laser power.

An experiment to measure γ-ray asymmetry A γ with a high precision in neutron-proton radiative capture is under construction at LANSCE. The experiment will determine the weak pion-nucleon coupling constant H π 1 ,, 30% of its predicted value.

Ordinary chondrite finds, terrestrial age dated using 14C analyses, from different meteorite accumulation sites, have been examined by Mossbauer spectroscopy to quantitatively determine terrestrial oxidation. We observe differences in weathering rates between sites, and also between different chondrite groups. A comparison of weathering over time, and its effect in ‘eroding’ meteorites, together with the number and mass distribution of meteorites in each region, enables us to derive estimates of the number of meteorite falls over a given mass per year. Studies of how the oxygen isotopic composition of samples varies with weathering indicate that incipient alteration may occur without a pronounced isotopic effect, possibly due to weathering of silicates to topotactically oriented smectite confined spaces where the water volume is limited. This finding has profound implications for the use of oxygen isotopes as a tool in understanding water–rock interaction. It also may reconcile previously contradictory data regarding the nebular or asteroidal location of pre-terrestrial aqueous alteration. Finally, Mossbauer spectroscopy is also found to be a useful tool in determining mineral abundance in carbonaceous chondrites, where a fine-grained matrix makes traditional approaches inapplicable. Again, the results have implications for the modification of chondritic materials in the early solar system.

The initial segment (IS) of the epididymis plays an essential role in male fertility. The IS epithelium is undifferentiated and nonfunctional at birth. Prior to puberty, the epithelium undergoes differentiation that leads to the formation of a fully functional organ. However, the mechanistic details of this program are not well understood. To explore this further, we used genetic engineering to create a kinase dead allele of the ROS1 receptor tyrosine kinase in mice and studied the effects of ROS1 tyrosine kinase activity on the differentiation of the IS epithelium. We show that the expression and activation of ROS1 coincides with the onset of differentiation and is exclusively located in the IS of the maturing and adult mouse epididymides. Here we demonstrate that the differentiation of the IS is dependent on the kinase activity of ROS1 and its downstream effector MEK1/2-ERK1/2 signaling axis. Using genetic engineering, we show that germ line ablation of ROS1 kinase activity leads to a failure of the IS epithelium to differentiate, and as a consequence sperm maturation and infertility were dramatically perturbed. Pharmacological inhibition of ROS1 kinase activity in the developing epididymis, however, only delayed differentiation transiently and did not result in infertility. Our results demonstrate that ROS1 kinase activity and the ensuing MEK1/2-ERK1/2 signaling are necessary for the postnatal development of the IS epithelium and that a sustained ablation of ROS1 kinase activity within the critical window of terminal differentiation abrogate the function of the epididymis and leads to sterility.

The epithelium that lines the epididymal duct establishes the optimal milieu in which spermatozoa mature, acquire motility, and are stored. This finely tuned environment also protects antigenic sperm against pathogens and autoimmunity, which are potential causes of transient or permanent infertility. The epididymal epithelium is pseudostratified and contains basal cells (BCs) that are located beneath other epithelial cells. Previous studies showed that in the mouse epididymis, BCs possess macrophage-like characteristics. However, we previously identified a dense population of cells belonging to the mononuclear phagocyte (MP) system (comprised of macrophages and dendritic cells) in the basal compartment of the mouse epididymis and showed that a subset of MPs express the macrophage marker F4/80. In the present study, we evaluate the distribution of BCs and MPs in the epididymis of transgenic CD11c-EYFP mice, in which EYFP is expressed exclusively in MPs, using antibodies against the BC marker keratin 5 (KRT5) and the macrophage marker F4/80. Immunofluorescence labeling for laminin, a basement membrane marker, showed that BCs and most MPs are located in the basal region of the epithelium. Confocal microscopy showed that in the initial segment, both BCs and MPs project intraepithelial extensions and establish a very intricate network. Flow cytometry experiments demonstrated that epididymal MPs and BCs are phenotypically distinct. BCs do not express F4/80, and MPs do not express KRT5. Therefore, despite their proximity and some morphological similarities with peritubular macrophages and dendritic cells, BCs do not belong to the MP system.

It has been reported (Chapman et al. 1989, in Asteroids II, edited by R. P. Binzel, T. Gehrels, and M. S. Matthews, Univ. of Arizona Press, Tucson, p. 386) that the shapes of asteroid families tend to be asymmetric, with a relative flattening along the line toward the Sun. This article addresses that observation. We develop a simple model for this, with an initially localized cluster circularly orbiting the Sun in the ecliptic plane, and acted upon by a background of weak stochastic forces. The model's linearized equations of motion are such that a component of random force, perpendicular to the radius, acts back to affect the radial motion. The result is a flattening, over time, toward the Sun.

We have modeled single-body meteoroid atmospheric entry speeds at Mars and the effect of drag and ablation, and identify a narrow range of small masses (10–50 g) that should impact Mars at survivable speeds. The rate of oxidative weathering is much lower than that on Earth, so this small flux of meteorites could give rise to significant accumulations: ca. 5×10 2 to 5×10 5 meteorites greater than 10 g in mass per square kilometer. Given that extremely large numbers of meteorites may be present on Mars, future sample-return missions should consider the real possibility that they may recover meteoritic material. Due to the low weathering rate, meteorites may survive on the surface of Mars for more than 10 9 years, preserving a record of the temporal variability of the meteoroid flux and the compositional evolution of the meteoroid complex. Intact carbonaceous chondrites may also preserve organic compounds from degradation by ultraviolet radiation. Terrestrial meteorites may be present, but would probably be sterile.

The weak interaction between neutrons and protons has never been resolved experimentally. In analogy with the strong NN interaction, the weak NN interaction at low energy can be parametrized in terms of a meson exchange model with parity violating meson–nucleon couplings. Unlike the measured proton–proton weak interaction, the neutron–proton weak interaction is sensitive to the weak pion–nucleon coupling constant Hπ1. This coupling, which is responsible for the longest-ranged part of the weak NN interaction and is therefore an essential part of any description of weak interactions in nuclei, remains undetermined despite many years of effort. A measurement of the gamma ray directional asymmetry Aγ in the capture of polarized neutrons by parahydrogen has been proposed at Los Alamos National Laboratory. The goal of this experiment is to determine Aγ with a relative standard uncertainty of

We consider some mathematical properties of Weyl-like quantizations based on two families of orderings of e : the first family, WW interpolates between Wick U = 1) and antiWick (/I = — 1) ordering, while the second family, Wco,^, interpolates between the Q-(//=!) and P-(fj.= — 1) orderings. The ordering W(o, and for Wu.o with — l

We find that of three phase operator models, only the Weyl quantization of the classical phase angle relates directly to the statistical mechanics treatment of a basic laser model.

This article considers the origins of DNA damage in human spermatozoa, the methods that are available to monitor this aspect of semen quality and the clinical significance of such measurements. DNA damage in spermatozoa appears to be largely oxidative in nature, inversely correlated with levels of nuclear protamination and frequently associated with the activation of a truncated apoptotic pathway. DNA base adducts formed as a result of oxidative attack are released from the spermatozoa into the extracellular space through the action of a glycosylase, OGG1. This creates an abasic site, which is not resolved until fertilization because spermatozoa do not possess the molecular machinery needed to continue the base excision repair pathway. The abasic sites so generated in human spermatozoa are readily detected by SCSA or the Comet assay; however, no signal is detectable with TUNEL. This is because spermatozoa lack the enzyme (APE1) needed to create the free 3' hydroxyl groups required by this detection system. Nevertheless, spermatozoa do eventually become TUNEL positive as they enter the perimortem. The American Society of Reproductive Medicine Practice Committee has suggested that DNA damage in spermatozoa should not be assessed because the correlation with pregnancy is inconsistent across independent studies. However, this is a straw man argument. The reason why such assays should be undertaken is not just that they reflect the underlying quality of spermatogenesis but, more importantly, that the DNA damage they reveal may have detrimental effects on the developmental normality of the embryo and the health of possible future children.

DNA repair has long been considered impossible in human spermatozoa due to the high level of DNA compaction observed in these cells. However, detailed examination of the base excision repair pathway in human spermatozoa has revealed the presence of an enzyme critical to this pathway, 8-oxoguanine DNA glycosylase 1 (OGG1). This glycosylase was associated with the sperm nucleus and mitochondria and could actively excise 8-hydroxy-2'-deoxyguanosine (8OHdG), releasing this adduct into the extracellular space. This activity was significantly reduced in the presence of cadmium (II), a recognized inhibitor of OGG1, in a time- and dose-dependent manner (P

The abundance of ferric iron, produced by weathering in ordinary chondrites collected from hot desert regions, is related to their terrestrial age, enabling a variety of processes involved in meteorite weathering to be deduced. Fe0/Fe2+/Fe3+ content was measured quantitatively by 57Fe Mossbauer spectroscopy. It is observed that meteorites from different regions are oxidised at different rates. We also propose the tentative hypothesis that one source of scatter in total oxidation versus terrestrial age for a region is climatic change. A mechanism to explain the variable response to climatic conditions involves the high initial porosity of samples being reduced as ferric oxides and other alteration products are produced. Reliable recovery data from a meteorite accumulation site (Roosevelt County, New Mexico, USA) and a quantitative measure of weathering and terrestrial age permit an estimate of the flux of meteorites to the Earth's surface. Having established a decay constant for meteorites, and accounting for the area of searches and pairing, we estimate an accumulation rate of 159 falls of mass greater than 20 g per 106 km2 per yr. This calculation is distinct from, but in broad agreement with, previous estimates from camera observations, suggesting that the accumulation rate of meteorite falls to the Earth's surface has remained essentially unchanged over the last 50,000 years at between 59 and 159 falls of mass exceeding 20 g per 106 km2 per yr. The error for both methods is approximately a factor of 2.

Endproducts of anaerobic fermentation, volatile fatty acids (VFAs), occur in the intestines of fish but no direct comparisons exist between VFA levels in fish with differing feeding ecologies during different seasons. We measured intestinal concentrations of six types of VFA in the upper and lower intestines of two freshwater omnivores (Cyprinus carpioi and Dorosoma cepedianum), and one piscivore (Micropterus salmoides) during the spring, summer and autumn. Acetate occurred in all species, and was highest in M. salmoides. In all species, concentrations were similar between upper and lower guts and higher during the summer. All three species contained anerobic bacteria and C. carpio and D. cepedianum contained cellulolytic types. Scanning electron microscopy revealed extensive colonization and suggested microbial breakdown of digesta in M. salmoides. In radio-tracer experiments, C. carpio dosed orally with [2–14C] acetate contained label in liver, muscle and blood tissues. Amounts of intestinal VFA did not appear to increase in species with refractile diets, and low VFA in D. cepedianum suggests fermentation plays a minimal role in the nutrition of this species. Low levels of intestinal VFA during cool seasons are consistent with the hypothesis that temperature limits fermentation in these Species.

In a previous paper, we considered Weyl quantization of functions of the angle in phase space, in particular a phase operator Delta ( phi ) and the quantized exponentials Delta (e+or-1 phi ). In this paper we consider the first and second moments of these operators with respect to the harmonic oscillator Hermite states hn and the coherent states Phi alpha . Taking asymptotic limits we find, for example, that var[ Delta ( phi ); hn]= pi 2/3+O(log n/n) (n to infinity ) for the variance of Delta ( phi ) in the Hermite states. For the second moment of the phase operator in ||[ Delta ( phi )- theta ] Phi alpha ||2=O(1/| alpha |) as | alpha | tends to infinity, amongst other results.

In a series of papers, Barnett, Pegg (1986, 1988, 1989, 1992) and various co-authors have proposed a description of quantum phase by means of a collection of s-dimensional states and operators, s>or=1. We analyse the limiting procedure they employ for large s, which is known not to be compatible with quantum mechanics in the usual sense. Further, we supply a rigorous demonstration of the asymptotic limits of the `mean` and `variance` of their system of operators in coherent states. These values had previously been given but not justified mathematically. Our analysis, based on the asymptotic analysis of certain random variables, shows that the physical deductions that can be drawn from these limits are limited. We also prove that the (s+1)-dimensional `pure phase` LHW-states they consider form a sequence of approximate eigenvectors for the Weyl-quantized angle operator Delta ( phi ) and the Toeplitz phase operator X proposed by Garrison and Wong (1970), Popov and Yarunin (1992), and others. These states Xs( theta ), to our knowledge first introduced by Lerner, Huang and Waiters (1970), can be used to construct a system of measurement as in the usual quantum theory, sensitive to certain qualities of phase, but not all. Indeed, a feature of the Barnett-Pegg method, when it gives finite answers, is the construction of associated measurement systems for different observables. We give examples of sequences of (s+1)-dimensional devices which represent measurements significantly closer to ideal for X. This serves as a model for corresponding devices for Delta ( phi ), or indeed, any observable with a continuous spectrum, contingent on its spectral decomposition being obtained explicitly.

We consider the current state of the quest for a quantum phase operator, which started in the earliest days of quantum mechanics.4–7 Particular emphasis has been placed on analysis of the structure of the several distinct theories, both physical and mathematical, which has led us from classical function theory to the quantum theory of measurement.

Oxidative stress in the male germ line is known to be a key factor in both the etiology of male infertility and the high levels of DNA damage encountered in human spermatozoa. Because the latter has been associated with a variety of adverse clinical outcomes, including miscarriage and developmental abnormalities in the offspring, the mechanisms that spermatozoa use to defend themselves against oxidative stress are of great interest. In this context, the male germ line expresses three unique forms of thioredoxin, known as thioredoxin domain-containing proteins (Txndc2, Txndc3, and Txndc8). Two of these proteins, Txndc2 and Txndc3, retain association with the spermatozoa after spermiation and potentially play an important role in regulating the redox status of the mature gamete. To address this area, we have functionally deleted the sperm-specific thioredoxins from the male germ line of mice by either exon deletion (Txndc2) or mutation of the bioactive cysteines (Txndc3). The combined inactivation of these Txndc isoforms did not have an overall impact on spermatogenesis, epididymal sperm maturation, or fertility. However, Txndc deficiency in spermatozoa did lead to age-dependent changes in these cells as reflected by accelerated motility loss, high rates of DNA damage, increases in reactive oxygen species generation, enhanced formation of lipid aldehyde–protein adducts, and impaired protamination of the sperm chromatin. These results suggest that although there is considerable redundancy in the systems employed by spermatozoa to defend themselves against oxidative stress, the sperm-specific thioredoxins, Txndc2 and Txndc3, are critically important in protecting these cells against the increases in oxidative stress associated with paternal age.

The faunas associated with oceanic islands provide exceptional examples with which to examine the dispersal abilities of different taxa and test the relative contribution of selective and neutral processes in evolution. We examine the patterns of recent differentiation and the relative roles of gene flow and selection in genetic and morphological variation in the yellow warbler (Dendroica petechia aureola) from the Galápagos and Cocos Islands. Our analyses suggest aureola diverged from Central American lineages colonizing the Galápagos and Cocos Islands recently, likely less than 300 000 years ago. Within the Galápagos, patterns of genetic variation in microsatellite and mitochondrial markers suggest early stages of diversification. No intra-island patterns of morphological variation were found, even across steep ecological gradients, suggesting that either (i) high levels of gene flow may be homogenizing the effects of selection, (ii) populations may not have had enough time to accumulate the differences in morphological traits, or (iii) yellow warblers show lower levels of 'evolvability' than some other Galápagos species. By examining genetic data and morphological variation, our results provide new insight into the microevolutionary processes driving the patterns of variation.

We review some of the difficulties previously encountered in defining the phase operator for finite quantum systems. We then propose the Wigner-Weyl quantization of the angle function q> on phase space as the phase operator, and derive a closed expression for its matrix elements with respect to the Hermite functions. We also determine the quantization of el, which turns out to be a weighted shift operator, its spectrum and that of its adjoint. This is done in the framework of quantization of a certain symbol class of phase space distributions, specialized to those which depend on one variable only. After recalling some results for the position and momentum variables, we apply the scheme to functions of radius or angle. We give necessary and sufficient conditions for operators obtained by quantizing functions of the angle to be elements of ^ + [^(R)] and ^+ [^(R), L2(R)], and a sufficient condition for boundedness. We then consider the associated questions of commutation relations and uncertainties for operators in J^ + [5^(R), L2(R)], which we define as bilinear forms. As must be the case, the commutator between our phase operator and the number operator exhibits noncanonical terms. Not surprisingly, the Poisson bracket of their phase space symbols also exhibits a noncanonical term.

Motivated by applications to neutron spin filters and recent advances in spectrally narrowed laser diode arrays (LDAs), we are exploring spin exchange optical pumping of 3He at pressures near 1 bar. Among our more interesting results has been the production of glass cells with extremely long relaxation times. The best of these has a lifetime of T1=840 h [where the polarization decays versus time, t, as exp(−t/T1)], dominated by the dipole–dipole contribution of 950 h at a 3He partial pressure of 0.85 bar. Using a broadband LDA, we have obtained 55% 3He nuclear polarization in this cell. These results are particularly relevant to the application of 3He-based neutron spin filters to neutron scattering and weak interaction experiments. Applications to magnetometry and polarized gas magnetic resonance imaging are also possible.

The NPDGamma collaboration reports results from the first phase of a measurement of the parity violating up-down asymmetry ${A}_{\ensuremath{\gamma}}$ with respect to the neutron spin direction of $\ensuremath{\gamma}$ rays emitted in the reaction $\mathrm{nP\vec}+p\ensuremath{\rightarrow}d+\ensuremath{\gamma}$ using the capture of polarized cold neutrons on the protons in a liquid parahydrogen target. One expects parity-odd effects in the hadronic weak interaction between nucleons to be induced by the weak interaction between quarks. ${A}_{\ensuremath{\gamma}}$ in $\mathrm{nP\vec}+p\ensuremath{\rightarrow}d+\ensuremath{\gamma}$ is dominated by a $\ensuremath{\Delta}I=1$, ${}^{3}{S}_{1}$-${}^{3}{P}_{1}$ parity-odd transition amplitude in the n-p system. The first phase of the measurement was completed at the Los Alamos Neutron Science Center spallation source (LANSCE), with the result ${A}_{\ensuremath{\gamma}}=[\ensuremath{-}1.2\ifmmode\pm\else\textpm\fi{}2.1 (\mathrm{stat}.)\ifmmode\pm\else\textpm\fi{}0.2 (\mathrm{sys}.)]\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}7}$. We also report the first measurement of an upper limit for the parity-allowed left-right asymmetry in this reaction, with the result ${A}_{\ensuremath{\gamma},\mathrm{LR}}=[\ensuremath{-}1.8\ifmmode\pm\else\textpm\fi{}1.9 (\mathrm{stat}.)\ifmmode\pm\else\textpm\fi{}0.2 (\mathrm{sys}.)]\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}7}$. In this paper we give a detailed report on the theoretical background, experimental setup, measurements, extraction of parity-odd and parity-allowed asymmetries, analysis of potential systematic effects, and LANSCE results. The asymmetry has an estimated size of $5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}8}$ and the aim of the NPDGamma collaboration is to measure it to $1\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}8}$. The second phase of the measurement will be performed at the Spallation Neutron Source at Oak Ridge National Laboratory.

A Raman luminescence microscope has been used to determine the residual stresses around Vickers diamond indentations in a relatively large, well-polished, R-cut (102) ruby single crystal. The principle of the method is based on the fact that the frequencies of the luminescence R lines of the ruby shift in a systematic manner with applied stress. It is shown that the hydrostatic component of the residual stress around a 25 N Vickers indentation can be as high as about 2 GPa, and that its magnitude decreases as A/r3, where r is the distance from the centre of indentation and A is a constant. These measurements are shown to be in qualitative agreement with the predictions of the current analytical models, although the magnitudes of the measured residual stresses are an order of magnitude smaller than those predicted by theory. Possible reasons for these differences are discussed.

Malaria parasites use vertebrate hosts for asexual multiplication and Culicidae mosquitoes for sexual and asexual development, yet the literature on avian malaria remains biased towards examining the asexual stages of the life cycle in birds. To fully understand parasite evolution and mechanism of malaria transmission, knowledge of all three components of the vector-host-parasite system is essential. Little is known about avian parasite-vector associations in African rainforests where numerous species of birds are infected with avian haemosporidians of the genera Plasmodium and Haemoproteus. Here we applied high resolution melt qPCR-based techniques and nested PCR to examine the occurrence and diversity of mitochondrial cytochrome b gene sequences of haemosporidian parasites in wild-caught mosquitoes sampled across 12 sites in Cameroon. In all, 3134 mosquitoes representing 27 species were screened. Mosquitoes belonging to four genera (Aedes, Coquillettidia, Culex, and Mansonia) were infected with twenty-two parasite lineages (18 Plasmodium spp. and 4 Haemoproteus spp.). Presence of Plasmodium sporozoites in salivary glands of Coquillettidia aurites further established these mosquitoes as likely vectors. Occurrence of parasite lineages differed significantly among genera, as well as their probability of being infected with malaria across species and sites. Approximately one-third of these lineages were previously detected in other avian host species from the region, indicating that vertebrate host sharing is a common feature and that avian Plasmodium spp. vector breadth does not always accompany vertebrate-host breadth. This study suggests extensive invertebrate host shifts in mosquito-parasite interactions and that avian Plasmodium species are most likely not tightly coevolved with vector species.