Structural and electronic properties of silver/silicon interfaces and implications for solar cell performance

We present the results of an experimental and atomistic modelling investigation of the Sili- con/Silver (Si/Ag) interfaces found in industrial solar cells. We use small ab initio calculations to parameterize a new interatomic potential for the Si/Ag interaction. This interatomic potential is then validated against larger ab initio calculations as well as the results of previous experimental and theoretical studies of Si/Ag systems. The interatomic potential allows us to perform a large- scale search of the conformational space of Si/Ag interfaces identified from transmission electron microscopy (TEM) studies. The most favourable geometries thus identified are then used as the input for more accurate ab initio calculations. We demonstrate that the two interfaces which we identify experimentally have significantly different geometric and electronic structures. We also demonstrate how these different structures result in significantly different Schottky barriers at the interfaces

Decolonize this art history: Imagining a decolonial art history programme at Kalamazoo College

This article presents a case study of a decolonized curriculum development in the Art History programme at the small liberal arts institution Kalamazoo College (Michigan, USA). It discusses the curriculum plan, methods for learning, assessment and potential applications for this approach beyond the case study. Paying attention to questions about the origins of art history, and its long-established methods and canon within the Western academy, this article proposes that any approach to decolonizing an art history curriculum must take into account the frameworks and methods of the knowledge systems it employs, must continually assess, reflect and hold accountable those who participate in its implementation and maintenance, and, importantly, must recognize that decolonization work is a necessarily messy and ongoing process

The Microwave Response of Square Mesh Metamaterials

Metamaterials are a class of artificial material, known to produce electromagnetic (EM) responses not found in nature due to their engineered subwavelength structure. In this thesis very thin subwavelength meshes are utilised to form layered metamaterials. The EM characteristics of the transmission and reflection response from these materials, including the polarisation converting behaviour, are explored to further understanding and develop structures to exploit and control the propagation of microwave radiation. Original experimental studies are presented across two sections; the first examines the response of stacks assembled from metallic meshes and dielectric plates; the second explores a rotated layered structure formed of square symmetric elements in a square subwavelength array that demonstrates chirality through evanescent coupling of the near fields. When metallic meshes are excited with EM radiation below the cut off frequency, only evanescently decaying fields are supported in the holes. By combining these subwavelength metallic meshes with dielectric plates in different arrangements, remarkably wide bands of high transmission and low reflection may be observed. The non-interacting resonant modes allow the response to be tuned through a suitable choice of the metallic mesh geometry and the properties of the dielectric. Further the low frequency band edge and the bandwidth are not dependent on the number of unit cells in the stack; but are dependent on the properties of the unit cell. The second section demonstrates ``evanescent handedness'' proposed as a new type of chirality. Two subwavelength square arrays of square elements are rotated with respect to one another. When the rotated arrays are positioned far from one another in the propagation direction, each acts as an effective medium layer. However when placed in close proximity the structure is shown to rotate the plane of polarisation of the incident radiation. All these mesh based structures share the property of producing an EM response that is tunable by design, allowing a structure to be tailored to a specific application.EPSRC Industrial CASE award, Qineti

Metamaterial tunnel barrier gives broad band microwave transmission

© 2011 American Institute of PhysicsA simple structure comprising a metal mesh, symmetrically surrounded by subwavelength thickness dielectric layers, is shown to give near total microwave transmission over a broad frequency range. The mesh may be considered to be a tunnel barrier since it behaves as an ideal plasmonic metamaterial with a negative effective permittivity and no loss. The introduction of the mesh into the dielectric cavity imposes a finite gradient on the electromagnetic fields at the two mesh-dielectric interfaces. This defines a finite wavelength of the zeroth order Fabry-Pérot-type mode, which would otherwise be infinite. Suitable choice of the mesh parameters yields a broad band of near total transmission associated with the overlap of this zeroth order mode with that of the first order half-wavelength Fabry-Pérot-type resonanceQinetiQEngineering and Physical Sciences Research Council (EPSRC

The management of acne vulgaris in primary care: a cohort study of consulting and prescribing patterns using CPRD

Background Effective management of acne vulgaris in primary care involves support (usually provided over a number of consultations) and prescribing effective treatments. However, consulting and prescribing patterns for acne in primary care are not well described. Objective To describe the rate of primary care consultations and follow-up consultations; prescribing patterns, including overall use of acne related medications (ARM) and initial and follow-up prescribing, for acne vulgaris in the UK. Methods UK primary care acne consultations and prescriptions for ARMs were identified in the Clinical Practice Research Datalink (CPRD). Annual consultation rates (between 2004 and 2013) by age and gender, new consultations and consultations in the subsequent year; prescribing trends, prescribing during a new consultation and over the subsequent 90 days and year were calculated, using number of registered patients as the denominator. Results 65.9% of patients who had a new acne consultation had no further acne consultations in the subsequent year. 26.6%, 25.2%, 23.5% and 2.8% of patients were prescribed no ARM, an oral antibiotic, a topical antibiotic, or an oral plus topical antibiotic respectively during a new acne consultation. 59.9% and 38.5% of patients prescribed an ARM received no further ARM prescriptions in the following 90 days and one year respectively, despite most prescriptions being for 2 months or less. Prescribing rates for lymecycline and topical combined clindamycin/benzoyl peroxide increased substantially between 2004 and 2013. There were no important changes in consultation rates between 2004 and 2013. Conclusion These data suggest that patients with acne are receiving sub-optimal initial choice of ARMs, longitudinal care and prescribing

Targeted Gene Repression Using Novel Bifunctional Molecules to Harness Endogenous Histone Deacetylation Activity

Epigenome editing is a powerful method for life science research and could give rise to new therapies for diseases initiated or maintained by epigenetic dysregulation, including several types of cancers and autoimmune disorders. In addition, much is still unknown about the mechanisms by which histone-modifying proteins work in concert to properly regulate gene expression. To investigate and manipulate complex epigenetic interactions in live cells, we have developed a small molecule platform for specifically inducing gene repression and histone deacetylation at a reporter gene. We synthesized bifunctional ligands, or chemical epigenetic modifiers (CEMs), that contain two functional groups: a FK506 derivative capable of binding to a FKBP-Gal4 fusion transcription factor, and a histone deacetylase (HDAC) inhibitor that recruits HDAC-containing corepressor complexes. In our reporter cell line, which contains a GFP reporter allele upstream of a Gal4 DNA binding array in the murine Oct4 locus, our lead CEM repressed GFP expression by 50%. We also show that CEM recruitment of deacetylation activity causes marked deacetylation along our target loci. This system allowed us to detail the direct results of deacetylation to chromatin and measure the resulting gene expression in a chemically dependent and reversible manner. The CEMs system provides new insights into epigenetic gene regulation and has the potential to control disease-relevant gene regulation. The CEMs are derived from FDA-approved epigenetic modulator drugs, and use their pharmacology in a gene-specific way that avoids the toxicities and off-target effects caused by whole-cell application of these drugs

An Up-to-date Assessment of US Prostate Cancer Incidence Rates by Stage and Race: A Novel Approach Combining Multiple Imputation with Age and Delay Adjustment

Background: In the USA, it is unknown whether metastatic prostate cancer incidence has continued to increase and whether racial differences have persisted. Objective: Combining multiple imputation with age and delay adjustment, we provide an up-to-date, comprehensive assessment of US prostate cancer incidence trends by stage and race. Design, setting, and participants: From Surveillance Epidemiology and End Results (SEER)-18, 774 240 prostate cancer cases were diagnosed during 2004–2017. Outcome measurements and statistical analysis: Multiple imputation assigned prostate cancer stage to the 4.7% of cases with missing stage, which varied by year and race-ethnicity. SEER delay factors adjusted case counts to anticipated future data corrections. Twenty datasets were imputed, and Rubin's rules were used for summary estimation. Overall and stage-specific rates were estimated and stratified by race and age group. Joinpoint software identified significant temporal changes and estimated annual percentage changes. We compared these estimates without multiple imputation and delay adjustment. Results and limitations: Metastatic prostate cancer incidence increased during 2011–2017, with an annual percentage change of 5.5. This was followed by increases in localized and regional disease since 2014. Non-Hispanic black men continued to have the highest incidence, especially for metastatic disease. The increasing rate of metastatic prostate cancer in non-Hispanic white men aged 50–74 yr accelerated recently, and the incidence was 56% higher in 2017 than in 2004. Rates without multiple imputation and delay adjustment were quantitatively and qualitatively different. This observational study is unable to assign causes to observed changes in prostate cancer incidence. Conclusions: Multiple imputation and delay adjustment are essential for portraying accurately stage- and race-specific prostate cancer incidence as clinical practice evolves. Patient summary: In the USA, diagnosis of prostate cancer that has spread to distant sites (metastatic disease) continues to increase. Black men continue to have higher risks of being diagnosed with metastatic prostate cancer than other race-ethnicities. In the USA, metastatic prostate cancer incidence rates have continued to increase through 2017, and local and regional disease rates have also increased since 2014. Racial differences persist, with non-Hispanic Black men being at the highest risk

Thinking political sociology: beyond the limits of post-Marxism

This article is concerned with post-Marxism and materialism in the work of Judith Butler, Ernesto Laclau and Chantal Mouffe. As ‘post-Marxists’ these writers use ‘material’ in a variety of ways, all of which indicate limits and constraints. The article focuses on one version of ‘materialism’ in this work, a version that is more implied than elaborated, in which ‘material’ is equivalent to institutionalized performativity or sedimented discourse: to ‘objective’ social structures and institutions. Post-Marxists often use ‘the social’ as equivalent to ‘material’ in this sense, to gesture towards the context in which politics succeeds or fails. I argue that the specificities of ‘the social’ cannot be theorized from within the terms of post-Marxism itself and that Butler and Laclau acknowledge this limitation in their most recent work. I therefore conclude that post-Marxism needs a supplement that I call political sociology. This is a dangerous supplement in the Derridean sense: a necessary addition that destabilizes the value post-Marxism gives to the distinction between ‘social’ and ‘political’ in which the latter is the privileged term

Repressing gene transcription by redirecting cellular machinery with chemical epigenetic modifiers

Regulation of chromatin compaction is an important process that governs gene expression in higher eukaryotes. Although chromatin compaction and gene expression regulation are commonly disrupted in many diseases, a locus-specific, endogenous, and reversible method to study and control these mechanisms of action has been lacking. To address this issue, we have developed and characterized novel gene-regulating bifunctional molecules. One component of the bifunctional molecule binds to a DNA-protein anchor so that it will be recruited to an allele-specific locus. The other component engages endogenous cellular chromatin-modifying machinery, recruiting these proteins to a gene of interest. These small molecules, called chemical epigenetic modifiers (CEMs), are capable of controlling gene expression and the chromatin environment in a dose-dependent and reversible manner. Here, we detail a CEM approach and its application to decrease gene expression and histone tail acetylation at a Green Fluorescent Protein (GFP) reporter located at the Oct4 locus in mouse embryonic stem cells (mESCs). We characterize the lead CEM (CEM23) using fluorescent microscopy, flow cytometry, and chromatin immunoprecipitation (ChIP), followed by a quantitative polymerase chain reaction (qPCR). While the power of this system is demonstrated at the Oct4 locus, conceptually, the CEM technology is modular and can be applied in other cell types and at other genomic loci