Detecting Stealth Dark Matter Directly through Electromagnetic Polarizability.

We calculate the spin-independent scattering cross section for direct detection that results from the electromagnetic polarizability of a composite scalar "stealth baryon" dark matter candidate, arising from a dark SU(4) confining gauge theory-"stealth dark matter." In the nonrelativistic limit, electromagnetic polarizability proceeds through a dimension-7 interaction leading to a very small scattering cross section for dark matter with weak-scale masses. This represents a lower bound on the scattering cross section for composite dark matter theories with electromagnetically charged constituents. We carry out lattice calculations of the polarizability for the lightest "baryon" states in SU(3) and SU(4) gauge theories using the background field method on quenched configurations. We find the polarizabilities of SU(3) and SU(4) to be comparable (within about 50%) normalized to the stealth baryon mass, which is suggestive for extensions to larger SU(N) groups. The resulting scattering cross sections with a xenon target are shown to be potentially detectable in the dark matter mass range of about 200-700 GeV, where the lower bound is from the existing LUX constraint while the upper bound is the coherent neutrino background. Significant uncertainties in the cross section remain due to the more complicated interaction of the polarizablity operator with nuclear structure; however, the steep dependence on the dark matter mass, 1/m(B)(6), suggests the observable dark matter mass range is not appreciably modified. We briefly highlight collider searches for the mesons in the theory as well as the indirect astrophysical effects that may also provide excellent probes of stealth dark matter.

Two-color gauge theory with novel infrared behavior.

Using lattice simulations, we study the infrared behavior of a particularly interesting SU(2) gauge theory, with six massless Dirac fermions in the fundamental representation. We compute the running gauge coupling derived nonperturbatively from the Schrödinger functional of the theory, finding no evidence for an infrared fixed point up through gauge couplings g(2) of order 20. This implies that the theory either is governed in the infrared by a fixed point of considerable strength, unseen so far in nonsupersymmetric gauge theories, or breaks its global chiral symmetries producing a large number of composite Nambu-Goldstone bosons relative to the number of underlying degrees of freedom. Thus either of these phases exhibits novel behavior.

Parity doubling and the S parameter below the conformal window.

We describe a lattice simulation of the masses and decay constants of the lowest-lying vector and axial resonances, and the electroweak S parameter, in an SU(3) gauge theory with N(f)=2 and 6 fermions in the fundamental representation. The spectrum becomes more parity doubled and the S parameter per electroweak doublet decreases when N(f) is increased from 2 to 6, motivating study of these trends as N(f) is increased further, toward the critical value for transition from confinement to infrared conformality.

Adaptive multigrid algorithm for the lattice Wilson-Dirac operator.

We present an adaptive multigrid solver for application to the non-Hermitian Wilson-Dirac system of QCD. The key components leading to the success of our proposed algorithm are the use of an adaptive projection onto coarse grids that preserves the near null space of the system matrix together with a simplified form of the correction based on the so-called γ5-Hermitian symmetry of the Dirac operator. We demonstrate that the algorithm nearly eliminates critical slowing down in the chiral limit and that it has weak dependence on the lattice volume.

Toward TeV conformality.

We study the chiral properties of an SU(3) gauge theory with N{f} massless Dirac fermions in the fundamental representation when N{f} is increased from 2 to 6. For N{f}=2, our lattice simulations lead to a value of psi psi/F{3}, where F is the Nambu-Goldstone-boson decay constant and psi psi is the chiral condensate, which agrees with the measured QCD value. For N{f}=6, this ratio shows significant enhancement, presaging an even larger enhancement anticipated as N{f} increases further, toward the critical value for transition from confinement to infrared conformality.

Role of calcium ions in the control of embryogenesis of Xenopus. Changes in the subcellular distribution of calcium in early cleavage embryos after treatment with the ionophore A23187.

Treatment of stage 5 Xenopus embryos with the ionophore A23187 for only 10 min, in the absence of extracellular Mg2+ and Ca2+, causes cortical contractions and a high incidence of abnormal embryos during subsequent development. Cation analysis shows that divalent ions are not lost from the embryos, but that Ca2+ is redistributed within the subcellular fractions. Ca2+ is probably released from yolk platelets and/or pigment granules by the action of A23187, [Ca2+] rises in the cytosol, and the mitochondria attempt to take up this free Ca2+. The mitochondria concomitantly undergo characteristic ultrastructural transformations, changing towards energized-twisted and energized-zigzag conformations. A23187 allows these changes to be demonstrated in situ. Extracellular divalent cations (10(-4) M) interfere with this intracellular action of A23187. Intracellular accumulation of Na+ (by treatment with ouabain) or Li+ also causes abnormal development, probably by promoting a release of Ca2+ from the mitochondria. It is suggested (a) that all these treatments cause a rise in [Ca2+]i which interferes with normal, integrated cell division, so causing, in turn, abnormal embryogenesis, (b) that levels of [Ca2+]i are of importance in regulating cleavage, (c) that the mitochondria could well have a function in regulating [Ca2+]i during embryogenesis in Xenopus, and (d) that vegetalizing agents may well act by promoting a rise in [Ca2+]i in specific cells in the amphibian embryo.

Inability of the activated partial thromboplastin time to predict heparin levels. Time to reassess guidelines for heparin assays.

BACKGROUND: In treating venous thromboembolic disorders, patient outcomes appear to correlate with heparin levels. Due to pharmacokinetic and pharmacodynamic variations, a relationship between heparin dose and level cannot be reliably predicted in individual patients. Some patients have low heparin levels despite therapeutic activated partial thromboplastin times (aPTTs), which may increase their risk for recurrent thromboembolism. Patients with high heparin requirements appear to have fewer bleeding episodes with heparin level-guided therapy. The aPTT does not reliably correlate with heparin blood concentrations or antithrombotic effects. Consequently, heparin therapy monitored with heparin levels may be more effective and safer. OBJECTIVES: To prospectively determine whether (1) the aPTT therapeutic range adequately predicts heparin levels in 38 patients used to establish the therapeutic aPTT range as is currently recommended and (2) whether 3 paired sets of aPTT-antifactor Xa levels provide the basis for using aPTTs to predict subsequent heparin levels in individual patients (n = 27) receiving intravenous heparin for coronary artery disease or venous thromboembolic disease. RESULTS: In the therapeutic aPTT range established, the R2 value for the relationship was 0.4. Prediction intervals were wide. For an aPTT of 60 seconds, the 95% prediction interval estimates were heparin levels of 0.05 to 1.0 U/mL. In individual patients, the aPTT-antifactor Xa relationship had an average R2 value of 0.75. There was no consistent relationship between the aPTT and anti-factor Xa level in a significant number of patients. CONCLUSIONS: The aPTT does not appear to be a useful surrogate for heparin levels. These findings suggest that the current recommendations on the use of heparin levels should be expanded.

Ultrasound-guided embryo transfer: a controlled trial.

Embryo transfer (ET) was performed in 94 patients using transvaginal ultrasound guidance. Pregnancy rates were increased over a control group of 246 patients, although statistical significance was reached only in the subgroup of single ETs. Advantages over the traditional blind technique of ET were observed. Acceptance of the procedure by both clinicians and patients was high.

Drug-nitrite interactions in human saliva: effects of food constituents on carcinogenic N-nitrosamine formation.

A simple and rapid high-pressure liquid chromatographic assay for monitoring N-nitrosodimethylamine (NDMA) in human saliva was developed. The method was used to study in vitro the effects of common food constituents on NDMA formation in saliva from the interaction of salivary nitrite with aminopyrine and oxytetracycline. Natural phenolic compounds, caffeic acid, and tannic acid, and synthetic additives, erythorbic acid, sorbic acid, propyl gallate, and butylated hydroxytoluene--all inhibited NDMA formation (20-80%). With ascorbic acid, up to 90% inhibition of NDMA synthesis in saliva was observed. In contrast, chlorogenic acid (a phenolic component of coffee) acted as a catalyst (up to 48% increase) of the nitrosamine formation under identical experimental conditions.

Modification of food cariogenicity in rats by mineral-rich concentrates from milk.

Dairy products, including milk, cheese, and casein, can reduce the caries-causing potential of cariogenic substrates as measured in various animal, plaque acidity, and in vitro systems. Although the mechanisms responsible for protection are not completely identified, substances containing Ca and P may contribute to the protective potential by reducing demineralization and/or promoting remineralization of enamel. Casein may reduce demineralization by forming a protective coat on the enamel surface. By means of a rat model, this study evaluated the ability of three casein-free milk mineral concentrates with various levels of whey protein, calcium, and phosphate to modify the cariogenicity of a powdered diet containing 20% sucrose. Analysis of these data indicates that there were no significant differences among groups for weight gain, total food consumption, or feeding frequency, as monitored by a computer-based infrared activity monitor. All three mineral concentrates significantly reduced buccal caries, and two of the three reduced sulcal caries by from 10 to 30%. The analysis further shows that casein-free milk mineral fractions can modify the cariogenicity of sucrose-containing foods in a rat model.

The application of molecular modelling to the interpretation of inverse gas chromatography data.

The use of molecular modelling in the interpretation of inverse gas chromatography data is discussed. Crystal faces can be visualised and likely cleavage planes calculated using the surface attachment energies. Assuming that the preferred cleavage plane is the crystal face with the smallest attachment energy then the predominant crystal faces of a crystalline particle can be predicted. Surface adsorption can be modelled using Van der Waals and electrostatic interactions to evaluate the interaction energies between individual atoms of the probe molecule and atoms of the test molecule orientated as in the surface. Using examples of pharmaceutical materials, modelling has been shown to be successful in the understanding of changes in the surface energetics.

Luteinizing hormone and follicle stimulating hormone induce premature condensation of chromatin in goat (Capra hircus) oocytes.

This study tested the hypothesis that premature condensation of chromatin in goat oocytes following superovulation with 1200 i.u. pregnant mare serum gonadotrophin (PMSG) is mediated by the high luteinizing hormone (LH) activity inherent in this gonadotrophin. Goats were treated with either a standard (3.95 mL) or high (7.90 mL) dose of a highly purified follicle-stimulating hormone (FSH) preparation (Ovagen), and different doses of human chorionic gonadotrophin (hCG) were added to increase the level of LH bioactivity during superovulation. The meiotic status of oocytes obtained at sponge withdrawal was compared between different treatments and correlated with profiles of LH bioactivity in peripheral plasma. Injection of 100 i.u. hCG (which gave a plasma LH profile comparable to 1200 i.u. PMSG) or 200 i.u. hCG resulted in significantly more oocytes showing premature condensation of chromatin without germinal vesicle breakdown than with 25 i.u. hCG or treatment with FSH alone. Nevertheless, nuclear maturation was also prematurely activated in a significant number of oocytes with a high dose of FSH alone, even though LH bioactivity was not detected in plasma. It is concluded that high LH bioactivity during superovulation of goats with gonadotrophins activates the initial stages of nuclear maturation in oocytes. However, highly purified FSH preparations in high doses can also induce this apparent abnormality in the timing of oocyte maturation through mechanisms unrelated to any LH contamination.

Premature condensation of chromatin induced in goat (Capra hircus) oocytes after gonadotrophin treatment.

In comparison with ovine follicle stimulating hormone (FSH), superovulation of goats with pregnant mare serum gonadotrophin (PMSG) produced premature ovulations within 48 h of drug administration. To test the hypothesis that this may be associated with a differential effect of the two drugs on oocyte maturation, we have compared the meiotic status of oocytes obtained at three different time intervals from animals treated with 1200 i.u. PMSG or 12 mg ovine FSH and from untreated control animals. Significantly more oocytes from PMSG-treated, compared with control and FSH-treated, animals showed premature condensation of chromatin at both the time of sponge withdrawal and 20 h later. The chromatin condensation was, however, not associated with germinal vesicle breakdown. In contrast, when oocytes were examined 6 h before the expected time of ovulation following human chorionic gonadotrophin (hCG) injection, no significant difference was found in the proportion of oocytes undergoing germinal vesicle breakdown between the three treatment groups, with most oocytes being at the metaphase I or II stage of meiosis. We conclude that superovulation of goats with PMSG at a dose resulting in a high incidence of premature ovulations is associated with premature activation of the initial stages of nuclear maturation in oocytes. In contrast, although treatment with 12 mg ovine FSH did not cause premature ovulations, it was not totally devoid of premature chromatin-condensing activity in oocytes.

The changes in surface energetics with relative humidity of carbamazepine and paracetamol as measured by inverse gas chromatography.

The surface energetic parameters of carbamazepine and paracetamol have been studied using inverse gas chromatography modified to produce dry and ambient conditions within the column. The values of the dispersive component of the surface free energy (gamma(S)D) do not change significantly at the increased relative humidity. In contrast the specific component of the free energy of adsorption (-DeltaG(A)SP) as measured by polar probes, can either remain constant or decrease by up to 10%, depending on the material and the probe. This indicates that an increase in the relative humidity causes a decrease in the surface energetics of the powder surface. It is proposed that where the water molecules are adsorbing to the same sites as the polar probes, the interaction of these probes with the surface is decreased. To identify these sites, the preferential interaction of each probe, including water, with the drug molecule has been modelled.

Dental cariogenic evaluation of foods using human plaque pH and an experimental rat-caries model.

Five well-characterized foods were used to compare two systems for estimating the cariogenic potential of food: human plaque-acidity using interdental metallic touch electrodes, and cariogenicity testing in rats. Both systems identified the same food as the least cariogenic or acidogenic food and identified the same three foods as being both cariogenic in rats and acidogenic in man, although the ranking of these foods differed. The systems differed in their assessment of potato chips, a food high in cooked starch and low in free sugars. The results confirmed that non-acidogenic foods are non-cariogenic, but that foods acidogenic in man may exhibit a greater range of cariogenicity in rats. Data from both human plaque pH studies and rat caries models may permit better assessment of cariogenic potential of foods containing fermentable carbohydrates.

Interpretation of the differences in the surface energetics of two optical forms of mannitol by inverse gas chromatography and molecular modelling.

Inverse gas chromatography (IGC) has been successfully used to characterise the nature of the surface of two optical forms of mannitol, DL and betaD. This has shown that the surface energetics of the two forms are significantly different with the DL form having higher values for the interactions with the dispersive and basic probes. Molecular modelling was used to predict the slip planes by utilising attachment energy calculations and so the dominant faces exposed upon milling could be predicted. Imaging these faces showed that the orientation of the molecules at these surfaces differed between the two forms. A visual comparison of the faces indicated that the DL form had a higher density of acidic and dispersive sites exposed at the surfaces than the betaD form. The results from the modelling agreed with the trends seen in the changes in surface energetics as measured by IGC. This suggests that the components of the surface energetic terms reflect the density of exposed groups at the particle surfaces.

Adaptive multigrid algorithm for lattice QCD.

We present a new multigrid solver that is suitable for the Dirac operator in the presence of disordered gauge fields. The key behind the success of the algorithm is an adaptive projection onto the coarse grids that preserves the near null space. The resulting algorithm has weak dependence on the gauge coupling and exhibits very little critical slowing down in the chiral limit. Results are presented for the Wilson-Dirac operator of the 2D U(1) Schwinger model.