8,427 research outputs found

    Thermodynamics of relativistic quantum fields confined in cavities

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    We investigate the quantum thermodynamical properties of localised relativistic quantum fields, and how they can be used as quantum thermal machines. We study the efficiency and power of energy transfer between the classical gravitational degrees of freedom, such as the energy input due to the motion of boundaries or an impinging gravitational wave, and the excitations of a confined quantum field. We find that the efficiency of energy transfer depends dramatically on the input initial state of the system. Furthermore, we investigate the ability of the system to extract energy from a gravitational wave and store it in a battery. This process is inefficient in optical cavities but is significantly enhanced when employing trapped Bose Einstein condensates. We also employ standard fluctuation results to obtain the work probability distribution, which allows us to understand how the efficiency is related to the dissipation of work. Finally, we apply our techniques to a setup where an impinging gravitational wave excites the phononic modes of a Bose Einstein condensate. We find that, in this case, the percentage of energy transferred to the phonons approaches unity after a suitable amount of time. These results give a quantitative insight into the thermodynamic behaviour of relativistic quantum fields confined in cavities.Comment: 35 pages, 3 figures. Manuscript substantially updated. I. Fuentes also published as I. Fuentes-Guridi and I. Fuentes-Schulle

    Depending On The Weather And Other Stories

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    ABSTRACT Depending on the Weather and Other Stories is a collection of short stories set in the rural and small town communities of contemporary America. The problem my characters address is their changing relationship with the American Dream. While my baby boomer characters tend to believe the Dream is alive and achievable, their children are growing more disenchanted and skeptical of the Dream. The disconnections between these generations are largely due to a credibility gap and a shifting set of generational values. These values have shifted for the younger generation because of an evolving (or devolving) American culture. My stories are written in what Iâm calling the âdirty domestic,â a subgenre of dirty realism. This is an appropriate style of writing for my content because the genre is traditionally used to depict bleak worlds and discontented characters. Another traditional tenet of dirty realism is the use of violence. My work shows how violence plays a pivotal role in both the romantic and familial relationships within the genre. While communication isnât always easy for these types of characters, violence sometimes speaks the loudest. I anticipate Depending on the Weather and Other Stories being published and entering into the contemporary dialogue of American letters. I see this collection expressing similar concerns with American culture as other writers of my generation. Lastly, I view this collection as a finger on the pulse of the American discontent. The characters in this collection are ready for a better shake in life, even if they know one isnât coming

    Nigerian science teachers\u27 beliefs about effective science teaching, their pedagogical content knowledge, and how these influence science teaching

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    This study investigated Nigerian junior secondary science teachers\u27 beliefs about effective science teaching, their pedagogical content knowledge and how these influence their classroom teaching behaviour. The research is underpinned by a conceptual framework, which establishes a strong relationship between teachers\u27 beliefs about teaching, teachers\u27 pedagogical content knowledge and classroom teaching practices. The study was carried out in two phases. The first phase involved a survey of all junior secondary science teachers (N=70) from the 30 secondary schools in two Local Education Districts of Lagos State, Nigeria. The second phase involved in-depth case studies of three science teachers who were purposively selected. The case study data were collected through interviews, classroom observation sessions and document analysis. Findings from the study revealed that the teachers hold narrow, objectivist or realist views of the nature of science, and narrow and elitist views of the purpose of science teaching in schools. They also espoused beliefs consistent with knowledge transmission, teacher-centred, teacher-dominated classrooms in which students should play mainly passive roles of listening, observing the teacher and copying notes whilst under strict supervision of the teacher so as to maintain a quiet classroom for science teaching. Assessment practices are based on short paper and pencil periodic tests and terminal examinations, which are mainly for summative purposes. The teachers\u27 classroom behaviour reflected accurate knowledge of science content and an understanding of the social and physical environment in which their students are learning. However, their teaching practices reflected pedagogical knowledge and skills, and knowledge of student learning derived from the traditional knowledge transmission pedagogy, which is not consistent with current understanding, and best practices in science teaching and learning. Their teacher-centred practices are consistent with their knowledge transmission beliefs and their pedagogical content knowledge in relation to pedagogical strategies and how students learn in science. The study revealed that shortages of science textbooks, insufficient teaching facilities and large classes, limit teachers’ effectiveness in science teaching. More contemporary approaches that actively engage students in learning and develop scientific literacy in the Nigerian context have been recommended. The implications of these findings for initial teacher education, professional development, science curriculum and science teaching have been outlined

    Understanding and targeting the C-terminal Binding Protein (CtBP) substrate-binding domain for cancer therapeutic development

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    Cancer involves the dysregulated proliferation and growth of cells throughout the body. C-terminal binding proteins (CtBP) 1 and 2 are transcriptional co-regulators upregulated in several cancers, including breast, colorectal, and ovarian tumors. CtBPs drive oncogenic properties, including migration, invasion, proliferation, and survival, in part through repression of tumor suppressor genes. CtBPs encode an intrinsic dehydrogenase activity, utilizing intracellular NADH concentrations and the substrate 4-methylthio-2-oxobutyric acid (MTOB), to regulate the recruitment of transcriptional regulatory complexes. High levels of MTOB inhibit CtBP dehydrogenase function and induce cytotoxicity among cancer cells in a CtBP-dependent manner. While encouraging, a good therapeutic would utilize \u3e100-fold lower concentrations. Therefore, we endeavored to design better CtBP-specific therapeutics. The best of these drugs, 3-Cl and 4-Cl HIPP, exhibit nanomolar enzymatic inhibition and micromolar cytotoxicity and showed that CtBP enzymatic function is subject to allosteric interactions. Additionally, the function of the substrate-binding domain has yet to be examined in context of CtBP’s oncogenic activity. To this end, we created several point mutations in the CtBP substrate-binding pocket and determined key residues for CtBP’s enzymatic activity. We found that a conserved tryptophan in the catalytic domain is imperative for function and unique to CtBPs among dehydrogenases. Knowledge of this and other residues allows the directed synthesis of drugs with increased potency and higher CtBP specificity. Early work interrogated the importance of these residues in cell migration. Taken together, this work addresses the utility of the CtBP substrate-binding domain as a target for cancer therapeutics

    William Arbuthnot Lane (1856-1943): Surgical Innovator and His Theory of Autointoxication.

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    William Arbuthnot Lane contributed to the advancement of many fields of orthopedics, otolaryngology, and general surgery. He is credited for his no-touch technique and the invention of long-handled instruments, some of which are still in use today, to minimize tissue handling. He is most well known for his hypothesis that slowing of gastric contents could cause a variety of ailments and this became known as Lane\u27s disease. Although his surgical treatment of Lane\u27s disease is now defunct, it advanced the surgical technique in colorectal surgery. It seems likely that some of Lane\u27s autointoxication patients would be classified today as patients with colonic inertia, diverticulitis, colonic volvulus, and megacolon or, which are all treated with colectomy. Lane was a pioneer in multiple fields and a true general surgeon. He advanced colorectal surgery immensely and propelled the field of surgery into a new era