No-Go Theorems for Generalized Chameleon Field Theories

The chameleon, or generalizations thereof, is a light scalar that couple to matter with gravitational strength, but whose manifestation depends on the ambient matter density. A key feature is that the screening mechanism suppressing its effects in high-density environments is determined by the local scalar field value. Under very general conditions, we prove two theorems limiting its cosmological impact: i) the Compton wavelength of such a scalar can be at most Mpc at present cosmic density, which restricts its impact to non-linear scales; ii) the conformal factor relating Einstein- and Jordan-frame scale factors is essentially constant over the last Hubble time, which precludes the possibility of self-acceleration. These results imply that chameleon-like scalar fields have a negligible effect on the linear-scale growth history; theories that invoke a chameleon-like scalar to explain cosmic acceleration rely on a form of dark energy rather than a genuine modified gravity effect. Our analysis applies to a broad class of chameleon, symmetron and dilaton theories.Comment: 4 page

PRACTICAL SUPERSTITIONS: FENG SHUI IN ARCHITECTURE

China has experienced rapid growth and as China grows, so does its global influence. Chinese culture can be seen in countries all over the world, and its influence is evident in various cuisines, languages, and even architecture. However, despite the global trend towards a more modern style, there are various elements present in Chinese architecture that allow it to stand out from the rest. Various real-life structures embody key beliefs of Feng Shui, which is both a theory and a practice for connecting the mind, body, and spirit to one’s space or environment, anchored on the traditional Chinese worldview on the art of spatial alignment and orientation, and its relationship with humans and their environment. These architectural designs do not merely stem from cultural or ideological bases alone; they have practical, economical, and logical applications as well. These real-life examples highlight the practicality behind the practice of Feng Shui in architecture

Higher Order Anomaly Consistency Conditions: Renormalization and Non-Locality

We study the Slavnov-Taylor Identities (STI) breaking terms, up to the second order in perturbation theory. We investigate which requirements are needed for the first order Wess-Zumino consistency condition to hold true at the next order in perturbation theory. We find that: a) If the cohomologically trivial contributions to the first order ST breaking terms are not removed by a suitable choice of the first order normalization conditions, the Wess-Zumino consistency condition is modified at the second order. b) Moreover, if one fails to recover the cohomologically trivial part of the first order STI breaking local functional, the second order anomaly actually turns out to be a non-local functional of the fields and the external sources. By using the Wess-Zumino consistency condition and the Quantum Action Principle, we show that the cohomological analysis of the first order STI breaking terms can actually be performed also in a model (the massive Abelian Higgs-Kibble one) where the BRST transformations are not nilpotent.Comment: 14 pages, 4 figures, Latex and packages amsfonts, amssymb, amsthm and eps

Atmospheric Water Harvester

Atmospheric water harvesting uses the vapor-compression cycle to collect water from the moisture in the air. The system’s components include an evaporator, condenser, compressor, fan, and several expansion valves. Condensate from the air is then funneled into a receptacle, which determines the efficiency of the water harvesting system. For this senior project, the goal is to increase the efficiency of an existing atmospheric water harvester

Modulation of the endocannabinoid system in viable and non-viable first trimester pregnancies by pregnancy-related hormones

<p>Abstract</p> <p>Background</p> <p>In early pregnancy, increased plasma levels of the endocannabinoid anandamide (AEA) are associated with miscarriage through mechanisms that might affect the developing placenta or maternal decidua.</p> <p>Methods</p> <p>In this study, we compare AEA levels in failed and viable pregnancies with the levels of the trophoblastic hormones (beta-human chorionic gonadotrophin (beta-hCG), progesterone (P4) and (pregnancy-associated placental protein-A (PAPP-A)) essential for early pregnancy success and relate that to the expression of the cannabinoid receptors and enzymes that modulate AEA levels.</p> <p>Results</p> <p>The median plasma AEA level in non-viable pregnancies (1.48 nM; n = 20) was higher than in viable pregnancies (1.21 nM; n = 25; <it>P </it>= 0.013), as were progesterone and beta-hCG levels (41.0 vs 51.5 ng/mL; <it>P </it>= 0.052 for P4 and 28,650 vs 6,560 mIU/L; <it>P </it>= 0.144 for beta-hCG, respectively, but were not statistically significant). Serum PAPP-A levels in the viable group were approximately 6.8 times lower than those in the non-viable group (1.82 vs 12.25 mg/L; <it>P </it>= 0.071), but again these differences were statistically insignificant. In the spontaneous miscarriage group, significant correlations between P4 and beta-hCG, P4 and PAPP-A and AEA and PAPP-A levels were observed. Simultaneously, immunohistochemical distributions of the two main cannabinoid receptors and the AEA-modifying enzymes, fatty acid amide hydrolase (FAAH) and <it>N</it>-acylphosphatidylethanolamine-phospholipase D (NAPE-PLD), changed within both the decidua and trophoblast.</p> <p>Conclusions</p> <p>The association of higher AEA levels with early pregnancy failure and with beta-hCG and PAPP-A, but not with progesterone concentrations suggest that plasma AEA levels and pregnancy failure are linked <it>via </it>a mechanism that may involve trophoblastic beta-hCG, and PAPP-A, but not, progesterone production. Although the trophoblast, decidua and embryo contain receptors for AEA, the main AEA target in early pregnancy failure remains unknown.</p

The Impact of Surgery on Circulating Malignant Tumour Cells in Oral Squamous Cell Carcinoma

Importance: The extent to which surgical management of oral squamous cell carcinoma (OSCC) disseminates cancer is currently unknown. Objective: To determine changes in numbers of malignant cells released into systemic circulation immediately following tumour removal and over the first seven post-operative days. Design: An observational study from March 2019 to February 2021. Setting: This study was undertaken at Queen Mary University Hospital, Hong Kong. Participants: Patients with biopsy-proven oral SCC were considered for eligibility. Patients under 18 years of age, pregnant or lactating women and those unable to understand the study details or unable to sign the consent form were excluded. Twenty-two patients were enrolled (12 male and 10 female) with mean age of 65.5 years. Intervention: Primary tumour management was performed in accord with multi-disciplinary team agreement. Anaesthesia and post-operative care were unaltered and provided in accord with accepted clinical practice. Main Outcomes and Measures: Three types of malignant cells detected in peripheral blood samples were enumerated and sub-typed based on the presence of chromosomal aneuploidy and immunohistochemical characteristics. To test the hypothesis that malignant cells are released by surgery, the numbers of single circulating tumour cells (CTCs), circulating tumour microemboli (CTM) and circulating endothelial cells (CTECs) were recorded pre-operatively, upon tumour removal and the second and seventh post-operative days. Results: Of a potential 88 data collection points, specimens were not obtainable in 12 instances. Tumour removal resulted in a statistically significant increase in CTCs and a non-statistically significant rise in CTMs. CTCs, CTMs and CTECs were detected in the majority of patients up to the seventh post-operative day. Individual patients demonstrated striking increases in post-operative CTCs and CTECs numbers. Conclusions/Relevance: Surgical management of OSCC has a significant impact on the systemic distribution of cancer cells. Malignant cells persisted post-operatively in a manner independent of recognised staging methods suggesting differences in tumour biology between individuals. Further investigation is warranted to determine whether circulating malignant cell enumeration can be used to refine risk stratification for patients with OSCC