Standard Model Prediction for Direct CP Violation in K→ππ Decay.

We report the first lattice QCD calculation of the complex kaon decay amplitude A_{0} with physical kinematics, using a 32³×64 lattice volume and a single lattice spacing a, with 1/a=1.3784(68) GeV. We find Re(A_{0})=4.66(1.00)(1.26)×10(-7) GeV and Im(A_{0})=-1.90(1.23)(1.08)×10(-11) GeV, where the first error is statistical and the second systematic. The first value is in approximate agreement with the experimental result: Re(A_{0})=3.3201(18)×10(-7) GeV, while the second can be used to compute the direct CP-violating ratio Re(ϵ^{'}/ϵ)=1.38(5.15)(4.59)×10^{-4}, which is 2.1σ below the experimental value 16.6(2.3)×10(-4). The real part of A_{0} is CP conserving and serves as a test of our method while the result for Re(ϵ^{'}/ϵ) provides a new test of the standard model theory of CP violation, one which can be made more accurate with increasing computer capability.

QCD phase transition with chiral quarks and physical quark masses.

We report on the first lattice calculation of the QCD phase transition using chiral fermions with physical quark masses. This calculation uses 2+1 quark flavors, spatial volumes between (4 fm)(3) and (11 fm)(3) and temperatures between 139 and 196 MeV. Each temperature is calculated at a single lattice spacing corresponding to a temporal Euclidean extent of N(t) = 8. The disconnected chiral susceptibility, χ(disc) shows a pronounced peak whose position and height depend sensitively on the quark mass. We find no metastability near the peak and a peak height which does not change when a 5 fm spatial extent is increased to 10 fm. Each result is strong evidence that the QCD "phase transition" is not first order but a continuous crossover for m(π) = 135 MeV. The peak location determines a pseudocritical temperature T(c) = 155(1)(8) MeV, in agreement with earlier staggered fermion results. However, the peak height is 50% greater than that suggested by previous staggered results. Chiral SU(2)(L) × SU(2)(R) symmetry is fully restored above 164 MeV, but anomalous U(1)(A) symmetry breaking is nonzero above T(c) and vanishes as T is increased to 196 MeV.

An atomic charge model for graphene oxide for exploring its bioadhesive properties in explicit water.

Graphene Oxide (GO) has been shown to exhibit properties that are useful in applications such as biomedical imaging, biological sensors, and drug delivery. The binding properties of biomolecules at the surface of GO can provide insight into the potential biocompatibility of GO. Here we assess the intrinsic affinity of amino acids to GO by simulating their adsorption onto a GO surface. The simulation is done using Amber03 force-field molecular dynamics in explicit water. The emphasis is placed on developing an atomic charge model for GO. The adsorption energies are computed using atomic charges obtained from an ab initio electrostatic potential based method. The charges reported here are suitable for simulating peptide adsorption to GO.

Favorable adsorption of capped amino acids on graphene substrate driven by desolvation effect.

The use of graphene-based nanomaterials is being explored in the context of various biomedical applications. Here, we performed a molecular dynamics simulation of individual amino acids on graphene utilizing an empirical force field potential (Amber03). The accuracy of our force field method was verified by modeling the adsorption of amino acids on graphene in vacuum. These results are in excellent agreement with those calculated using ab initio methods. Our study shows that graphene exhibits bioactive properties in spite of the fact that the interaction between graphene and amino acids in a water environment is significantly weaker as compared to that in vacuum. Furthermore, the adsorption characteristics of capped and uncapped amino acids are significantly different from each other due to the desolvation effect. Finally, we conclude that when assessing protein-surface interactions based on adsorption of single amino acids, the minimum requirement is to use capped amino acids as they mimic residues as part of a peptide chain.

K→(ππ)(I=2) decay amplitude from lattice QCD.

We report on the first realistic ab initio calculation of a hadronic weak decay, that of the amplitude A(2) for a kaon to decay into two π mesons with isospin 2. We find ReA(2)=(1.436±0.063(stat)±0.258(syst))10(-8) GeV in good agreement with the experimental result and for the hitherto unknown imaginary part we find ImA(2)=-(6.83±0.51(stat)±1.30(syst))10(-13) GeV. Moreover combining our result for ImA(2) with experimental values of ReA(2), ReA(0), and ε'/ε, we obtain the following value for the unknown ratio ImA(0)/ReA(0) within the standard model: ImA(0)/ReA(0)=-1.63(19)(stat)(20(syst)×10(-4). One consequence of these results is that the contribution from ImA(2) to the direct CP violation parameter ε' (the so-called Electroweak Penguin contribution) is Re(ε'/ε)(EWP)=-(6.52±0.49(stat)±1.24(syst))×10(-4). We explain why this calculation of A(2) represents a major milestone for lattice QCD and discuss the exciting prospects for a full quantitative understanding of CP violation in kaon decays.

Expression of GFP can influence aging and climbing ability in Drosophila.

Green fluorescent protein (GFP) is widely used as a reporter transgene in a variety of organisms. Some of the advantages of using GFP include non-invasive visualization of biological events and/or tissues in live specimens and its benign nature. When GFP is expressed throughout the organism, in neurons and eyes, lifespan and climbing ability of flies are significantly decreased compared to similar crosses with a lacZ reporter. Also, GFP expression can have subtle effects on eye morphology, with neural and ubiquitous expression. Since GAL4/UAS expression of GFP can influence aging and climbing ability in the Drosophila system of directed gene expression, we found that the latter of these advantages, namely its harmless, non-toxic nature, can be conditional, depending upon the mode of expression and the biological endpoint. We suggest that caution should be used when using GFP to visualize cellular events, especially in long-term assays.

η and η' mesons from lattice QCD.

The large mass of the ninth pseudoscalar meson, the η', is believed to arise from the combined effects of the axial anomaly and the gauge field topology present in QCD. We report a realistic, 2+1-flavor, lattice QCD calculation of the η and η' masses and mixing which confirms this picture. The physical eigenstates show small octet-singlet mixing with a mixing angle of θ=-14.1(2.8)°. Extrapolation to the physical light quark mass gives, with statistical errors only, mη=573(6) MeV and mη'=947(142) MeV, consistent with the experimental values of 548 and 958 MeV.

Review of lattice results concerning low-energy particle physics: Flavour Lattice Averaging Group (FLAG).

We review lattice results related to pion, kaon, D- and B-meson physics with the aim of making them easily accessible to the particle-physics community. More specifically, we report on the determination of the light-quark masses, the form factor [Formula: see text], arising in the semileptonic [Formula: see text] transition at zero momentum transfer, as well as the decay constant ratio [Formula: see text] and its consequences for the CKM matrix elements [Formula: see text] and [Formula: see text]. Furthermore, we describe the results obtained on the lattice for some of the low-energy constants of [Formula: see text] and [Formula: see text] Chiral Perturbation Theory. We review the determination of the [Formula: see text] parameter of neutral kaon mixing as well as the additional four B parameters that arise in theories of physics beyond the Standard Model. The latter quantities are an addition compared to the previous review. For the heavy-quark sector, we provide results for [Formula: see text] and [Formula: see text] (also new compared to the previous review), as well as those for D- and B-meson-decay constants, form factors, and mixing parameters. These are the heavy-quark quantities most relevant for the determination of CKM matrix elements and the global CKM unitarity-triangle fit. Finally, we review the status of lattice determinations of the strong coupling constant [Formula: see text].

The prevention of infection in open fractures. An experimental study of the effect of antibiotic therapy.

Using an experimental rabbit model of a contaminated open fracture of the tibia that was fixed with an intramedullary pin, we assessed the effect of a single dose of cephradine in preventing post-traumatic osteomyelitis in which the infecting organism was Staphylococcus aureus. We paid particular attention to the effect of a delay in giving the antibiotic. The frequency of osteomyelitis in the animals in a control group (no antibiotic) was 91 per cent. When a single injection of cephradine was given one hour before inoculation with the bacteria, the rate was 30 per cent, a statistically significant reduction (p less than 0.01). When cephradine was not administered until one to four hours after inoculation with the bacteria, the average rate of osteomyelitis was 51 per cent, a 40 per cent reduction compared with the rate for the control group. The effect of the antibiotic therefore persisted even when the initial dose was delayed for four hours after bacterial inoculation.

Magnetic resonance imaging of the cerebello-pontine angle.

A variety of extra-axial lesions occurring at the cerebello-pontine angle was examined by magnetic resonance imaging (MRI). Differences in spin sequence characteristics were found between neurilemmomas and meningiomas, with neurilemmomas exhibiting a greater increase in T2 than meningiomas. The T1 images were of less value in differentiating between neurilemmomas and meningiomas but were of value in the diagnosis of vascular lesions, due to the decreased T1 of blood clot. The T1 images were also of value in the assessment of tumour size and in the diagnosis of an epidermoid cyst. Extension of tumour into the internal auditory meatus was seen on MRI with acoustic neuromas and with one other lesion. The transverse perspective was of greatest value in lesion assessment. The coronal perspective was useful in certain situations but the sagittal perspective was of minimal clinical value.

Magnetic resonance imaging of benign ovarian masses.

Forty-one patients with 45 pelvic mass lesions were assessed by magnetic resonance imaging (MRI). All lesions were initially considered to be benign ovarian masses with this diagnosis confirmed in 36 lesions. The characteristics on MRI are analysed and features useful in predicting histological type identified. Our results indicate that a high, though not absolute, level of diagnostic specificity should be obtainable in identification of ovarian pathology.

Magnetic resonance imaging and discography in the diagnosis of disc degeneration. A comparative study of 50 discs.

The lumbar spines of 22 patients were examined for disc degeneration by magnetic resonance imaging (MRI) and by discography. The results from 50 intervertebral discs visualised by both techniques were independently assessed and graded on a five-point scale from normality to gross degeneration and then compared. In 44 discs the results agreed. Of the six discs which gave differing results, four discrepancies were due to observer error and two to incorrect placement of the discographic needle. MRI was shown to be more accurate than discography in the diagnosis of disc degeneration. It has several major advantages, which should make it the investigation of choice.

Neutral-kaon mixing from (2+1)-flavor domain-wall QCD.

We present the first results for neutral-kaon mixing using (2+1)-flavors of domain-wall fermions. A new approach is used to extrapolate to the physical up and down quark masses from our numerical studies with pion masses in the range 240-420 MeV; only SU(2)_{L}xSU(2)_{R} chiral symmetry is assumed and the kaon is not assumed to be light. Our main result is B_{K};{MS[over ]}(2 GeV)=0.524(10)(28) where the first error is statistical and the second incorporates estimates for all systematic errors.

Is ureteric compression still necessary?

A prospective randomised trial was performed to examine the value of ureteric compression in intravenous urography. Calyceal distension improved during the urogram in 68% of kidneys when compression was used, in contrast to an improvement of 43% in patients not receiving compression. In both heavy patients and those with a large girth a trend towards improved distension was shown but was significant only in the former group.

An experimental model of post-traumatic osteomyelitis in rabbits.

An experimental model of a contaminated open fracture, using the tibia of male New Zealand white rabbits, is described. Post-traumatic osteomyelitis can be reliably induced in this model, with no systemic ill-effects. The characteristic bacteriological, radiological and histological findings are described. Inoculation of the fracture site with Staphylococcus aureus in a concentration of 10(6) bacteria caused osteomyelitis in two out of five rabbits. When the concentration of inoculum was increased to 10(7) organisms, osteomyelitis was seen in four out of five rabbits. No cases of infection were seen in the control animals. This is a simple and reliable model for studies into the prevention and treatment of post-traumatic osteomyelitis.

The prevention of infection in open fractures: an experimental study of the effect of fracture stability.

An experimental model of a contaminated open fracture has been developed. This model has been used to test the hypothesis that stable fixation of a contaminated open fracture will reduce its susceptibility to infection. The tibiae of male New Zealand white rabbits were fractured and then fixed with either a dynamic compression plate (stable group) or a loose-fitting intramedullary rod (unstable group). The fracture site was then inoculated with a standard inoculum of Staphylococcus aureus. There were 20 rabbits in the stable group and osteomyelitis developed in seven (35 per cent); in the unstable group 15 (71 per cent) out of 21 animals developed osteomyelitis. This difference in infection rates was statistically significant (P < 0.02). This experimental study supports the concept of stabilization of open fractures in man.

Computed tomography scan scout film for measurement of femoral axis in knee replacement.

We conclude that the CT scout film is a more accurate and reproducible method for FAA measurement. The cost difference is minimal and might be expected to lessen as overheads are reduced for the CT scanner.

The value of magnetic resonance imaging in the diagnosis of intracranial meningiomas.

Thirty-two patients suspected by Computed Tomography (CT) of having a meningioma were additionally imaged by Magnetic Resonance. Of these, seven patients had an eventual diagnosis other than meningioma. This represents a positive value of 76% for the diagnosis of meningioma by CT. Magnetic resonance imaging (MRI) improved positive predictive value to 86%. A diagnosis other than meningioma was made by MRI with greatest confidence when tumour signal intensity was either much greater or much less than that of grey matter. Comparison of Inversion Recovery (IR) and spin echo (SE) sequences showed IR to be superior for demonstration of supratentorial meningiomas. SE images were superior to IR in demonstrating calcification. MRI was of value in showing anatomical relationships, due to its multiplanar capacity and in demonstrating vessel patency. CT was generally superior in defining meningiomas and in demonstrating calcification.

The relative contribution of magnetic resonance imaging to the assessment and differential diagnosis of cerebellopontine angle mass lesions.

Forty-nine patients with a space occupying lesion in the cerebellopontine angle cistern were examined by computed tomography (CT), magnetic imaging (MRI) and, where appropriate, conventional neuroradiologic techniques. The presence of an intracanalicular extension and a high signal on T2 weighted sequences were typical of acoustic neuroma and allowed separation from meningioma. Contrast enhancement with gadolinium DTPA was particularly valuable in recurrent acoustic neuroma. Typically epidermoids had long T1 and T2 values. Sequences which highlight flow allow vascular lesions to be identified without the use of contrast media. In separating the several pathologies MRI was superior to CT and also gave information on tissue composition in acoustic neuroma.