Electroweak Baryogenesis and Colored Scalars

We consider the 2-loop finite temperature effective potential for a Standard Model-like Higgs boson, allowing Higgs boson couplings to additional scalars. If the scalars transform under color, they contribute 2-loop diagrams to the effective potential that include gluons. These 2-loop effects are perhaps stronger than previously appreciated. For a Higgs boson mass of 115 GeV, they can increase the strength of the phase transition by as much as a factor of 3.5. It is the analogue of this effect that is responsible for the survival of the tenuous electroweak baryogenesis window of the Minimal Supersymmetric Standard Model. We further illuminate the importance of these 2-loop diagrams by contrasting models with colored scalars to models with singlet scalars. We conclude that baryogenesis favors models with light colored scalars. This motivates searches for pair-produced di-jet resonances or jet(s) + missing energy.Comment: 12 pages, 5 figures; v2: minor changes, journal versio

Antifungal Activity Assessment of Selected Locally Sold Over-The-Counter Azole against Candida Isolates from Hospital and Community Settings of Rivers State, Nigeria

There seems to be multiple factors that could affect the performance of a drug which may range widely from measurements to packaging, storage, handling and standardization. Candida species are ubiquitous in nature and are found at different parts of the body, with some present as normal flora. However, drug abuse as mostly associated with the conscious intake of drugs without the guide or prescription of a physician, poses enormous challenge to personal and public health. Hence, this study was designed for comparative analysis of the antifungal activity of over the counter azole and standardized fluconazole disc on the Candida species isolated from community and hospital settings in Rivers State. All Candida isolates were inoculated onto a Sarbouraud dextrose agar plate to obtain a pure culture and then used for normal saline microscopy, germ tube test and carbohydrate assimilation tests to confirm Candida species. Antifungal susceptibility testing using the Kirby Bauer disc diffusion method was carried out and the data generated were type-set in Microsoft Excel version 2003, and transferred into statistical package for social sciences (SPSS), IBM version 21 for statistical analysis. The study results showed 59 Candida isolates with 11.9% Candida isolated testing negative to germ tube test while 88.1% of the tested positive to germ tube test. However, distribution of germ tube positive Candida species from hospital and community settings showed that the community setting had 90.6% germ tube positive Candida isolates and 9.4% germ tube negative Candida isolates while hospital settings showed 85.2% germ tube positive isolates and 14% germ tube negative isolates. In this study, 28.6% Non-albicans Candida (NAC) were susceptible to clotrimazole, 14.3% NAC were susceptible dose dependent while 57.1% were resistant to clotrimazole. However, fluconazole recorded 0% susceptibility dose dependence by Non-albicans Candida, 42.9% susceptibility and 57.1% resistance. Similarly, 63.5%, 15.4%, and 21.2% of Candida albicans were susceptible, susceptibility dose dependent and resistant respectively to fluconazole. While, 30.8%, 34.6% and 34.6% of Candida albicans were susceptible, susceptibility dose dependent and resistant to itraconazole. In conlusion, fluconazole had the best efficacy on non-albicans Candida while clotrimazole was best for killing Candida albicans It is believed that a change in attitude from self medication is very crucial as it remains a key factor that could be responsible for increased incidence of Candida species’ resistance to azole therapy. Furthermore, change towards adherence to antifungal drug regimes when encouraged and cultivated as a positive habit for all patients, could enhance monitoring of drug efficacy and clinical/treatment outcomes

Harnessing Wastewater for Renewable Energy (2013-2)

This case study explores the options for using wastewater to produce renewable energy in the context of a public wastewater treatment plant. It provides an opportunity for students to synthesize knowledge from resource economics, engineering, environmental science, agriculture, and public policy to develop a transdisciplinary approach to a socio-environmental issue. The case is designed for upper division undergraduate courses in resource economics or environmental engineering, but several modifications are provided graduate course applications. Students assume the role of a newly hired analyst at a consulting firm in Washington, DC, that specializes in renewable energy solutions. They are charged with proposing a system that uses wastewater to produce energy, while accounting for multiple constraints across disciplines. Students are provided with economic, political, environmental, and engineering data on four different solid waste disposal options and work in small groups to develop a proposed solution that balances these factors. They present and justify their suggested solutions in small-group presentations, and the case concludes with an instructor-led discussion of the relevant considerations

How Do Quasicrystals Grow?

Using molecular simulations, we show that the aperiodic growth of quasicrystals is controlled by the ability of the growing quasicrystal `nucleus' to incorporate kinetically trapped atoms into the solid phase with minimal rearrangement. In the system under investigation, which forms a dodecagonal quasicrystal, we show that this process occurs through the assimilation of stable icosahedral clusters by the growing quasicrystal. Our results demonstrate how local atomic interactions give rise to the long-range aperiodicity of quasicrystals.Comment: 4 pages, 4 figures. Figures and text have been updated to the final version of the articl

Van der Waals density functional: Self-consistent potential and the nature of the van der Waals bond

We derive the exchange-correlation potential corresponding to the nonlocal van der Waals density functional [M. Dion, H. Rydberg, E. Schroder, D. C. Langreth, and B. I. Lundqvist, Phys. Rev. Lett. 92, 246401 (2004)]. We use this potential for a self-consistent calculation of the ground state properties of a number of van der Waals complexes as well as crystalline silicon. For the latter, where little or no van der Waals interaction is expected, we find that the results are mostly determined by semilocal exchange and correlation as in standard generalized gradient approximations (GGA), with the fully nonlocal term giving little effect. On the other hand, our results for the van der Waals complexes show that the self-consistency has little effect at equilibrium separations. This finding validates previous calculations with the same functional that treated the fully nonlocal term as a post GGA perturbation. A comparison of our results with wave-function calculations demonstrates the usefulness of our approach. The exchange-correlation potential also allows us to calculate Hellmann-Feynman forces, hence providing the means for efficient geometry relaxations as well as unleashing the potential use of other standard techniques that depend on the self-consistent charge distribution. The nature of the van der Waals bond is discussed in terms of the self-consistent bonding charge.Comment: submitted to Phys. Rev.

Modified Higgs Boson Phenomenology from Gauge or Gaugino Mediation in the NMSSM

In the Next-to-Minimal Supersymmetric Standard Model (NMSSM), the presence of light pseudoscalars can have a dramatic effect on the decays of the Standard Model-like Higgs boson. These pseudoscalars are naturally light if supersymmetry breaking preserves an approximate U(1)_R symmetry, spontaneously broken when the Higgs bosons take on their expectation values. We investigate two classes of theories that possess such an approximate U(1)_R at the mediation scale: deformations of gauge and gaugino mediation. In the models we consider, we find two disjoint classes of phenomenologically allowed parameter regions. One of these regions corresponds to a limit where the singlet of the NMSSM largely decouples. The other can give rise to a Standard Model-like Higgs boson with a dominant branching into light pseudoscalars.Comment: 35 pages, 10 figure

Pancreatic Divisum: An Unusual Cause of Chronic Pancreatitis in a Young Patient

Pancreatic divisum is a condition that occurs in 4-14% of the population. Pancreatic divisum occurs in development when the ventral bud and dorsal bud of the pancreas fail to fuse. Patients with this condition are usually asymptomatic, however, 25-38% of these patients experience recurrent pancreatitis that may further progress to chronic pancreatitis. This case is of a 20-year-old female presenting with abdominal pain in the left and right upper quadrants of the abdomen with a significant history of recurrent pancreatitis since the age of seven. The patient was examined with computed tomography (CT), which identified pancreatitis. Further magnetic resonance cholangiopancreatography (MRCP) assisted in the diagnosis of a type III pancreatic divisum, given the remnant of short communication between the dorsal and ventral duct