Multimode analysis of non-classical correlations in double well Bose-Einstein condensates

The observation of non-classical correlations arising in interacting two to size weakly coupled Bose-Einstein condensates was recently reported by Esteve et al. [Nature 455, 1216 (2008)]. In order to observe fluctuations below the standard quantum limit, they utilized adiabatic passage to reduce the thermal noise to below that of thermal equilibrium at the minimum realizable temperature. We present a theoretical analysis that takes into account the spatial degrees of freedom of the system, allowing us to calculate the expected correlations at finite temperature in the system, and to verify the hypothesis of adiabatic passage by comparing the dynamics to the idealized model.Comment: 12 pages, 7 figure

Watching the hands of the Arabidopsis biological clock

Oligonucleotide and cDNA microarrays have been used to analyse the mRNA levels of 8,000 genes in Arabidopsis thaliana throughout the day/night cycle. Genes involved in signal transduction and in various metabolic pathways were found to be coordinately regulated by circadian rhythms and/or by light

Multi-epoch infrared photometry of the star forming region G173.58+2.45

We present a multi-epoch infrared photometric study of the intermediate-mass star forming region G173.58+2.45. Photometric observations are obtained using the near-infrared $JHKL'M'$ filters and narrow-band filters centered at the wavelengths of H$_2$ (1-0) S(1) (2.122 $\mu$m) and [FeII] (1.644 $\mu$m) lines. The H$_2$ image shows molecular emission from shocked gas, implying the presence of multiple star formation and associated outflow activity. We see evidence for several collimated outflows. The most extended jet is at least 0.25 pc in length and has a collimation factor of $\sim$ 10, which may be associated with a binary system within the central cluster, resolved for the first time here. This outflow is found to be episodic; probably occurring or getting enhanced during the periastron passage of the binary. We also find that the variable star in the vicinity of the outflow source, which was known as a FU Ori type star, is probably not a FU Ori object. However, it does drive a spectacular outflow and the variability is likely to be related to accretion, when large clouds of gas and dust spiral in towards the central source. Many other convincing accretion-outflow systems and YSO candidates are discovered in the field.Comment: 15 pages, 9 figures, accepted for publication in MNRA

The First Billion Years project: dark matter haloes going from contraction to expansion and back again

We study the effect of baryons on the inner dark matter profile of the first galaxies using the First Billion Years simulation between z=16-6 before secular evolution sets in. Using a large statistical sample from two simulations of the same volume and cosmological initial conditions, one with and one without baryons, we are able to directly compare haloes with their baryon-free counterparts, allowing a detailed study of the modifications to the dark matter density profile due to the presence of baryons during the first billion years of galaxy formation. For each of the ~ 5000 haloes in our sample we quantify the impact of the baryons using eta, defined as the ratio of dark matter mass enclosed in 100 pc in the baryonic run to its counterpart without baryons. During this epoch of rapid growth of galaxies, we find that many haloes of these first galaxies show an enhancement of dark matter in the halo centre compared to the baryon-free simulation, while many others show a deficit. We find that the mean value of eta is close to unity, but there is a large dispersion, with a standard deviation of 0.677. The enhancement is cyclical in time and tracks the star formation cycle of the galaxy; as gas falls to the centre and forms stars, the dark matter moves in as well. Supernova feedback then removes the gas, and the dark matter again responds to the changing potential. We study three physical models relating the motion of baryons to that of the dark matter: adiabatic contraction, dynamical friction, and rapid outflows. Abridged, see text for full abstractComment: accepted in MNRA

Assessment of Coating Performance on Waterwalls and Superheaters in a Pulverised Fuel-Fired Power Station

Protective coatings offer one route to increase the lives of heat exchangers in pulverised fuel power plants. A range of candidate coatings have been exposed on the waterwall and superheaters of a 500 MWe UK power station unit for periods of up to ~4 years (24,880 operating hours), during which time this unit was fired on a mixture of UK and world-traded coals. Both nickel- and iron-based candidate coatings were included, applied using high velocity oxy-fuel or arc-wire process; a selection of these also had a surface sealant applied to investigate its effectiveness. Dimensional metrology was used to evaluate coating performances, with SEM/EDX examinations used to investigate the various degradation mechanisms found. Both the waterwall and superheater environments generated their characteristic corrosion damage morphologies which depended on the radial positions around the tube. Coating performances were found to depend on the initial coating quality rather than composition, and were not improved by the use of a sealant

INVESTIGATING THE ROLES OF TAP63 AND TAP73 IN CUTANEOUS SQUAMOUS CELL CARCINOMA AND LUNG ADENOCARCINOMA

TP63 and TP73 (which encode p63 and p73, respectively) are highly conserved transcription factors with important roles in development and tissue homeostasis. Similar to their homolog, p53, both p63 and p73 have been shown to mediate tumor suppression in multiple tissue types. Interestingly, however, both genes are expressed as multiple isoforms, which appear to have different and, in many cases, antagonistic functions. Through the use of isoform-specific null alleles of p63 and p73 our lab and others have shown that the full-length N-terminal isoforms of p63 and p73 (referred to as TAp63 and TAp73, respectively) exhibit distinct functions in development, metabolism and tumor suppression. My thesis research focuses on understanding the conserved functions of TAp63 and TAp73 in tumorigenesis. To do so, I have utilized multiple model systems to investigate the contributions of TAp63 and TAp73 in the development and progression of cutaneous squamous cell carcinoma (cuSCC) and lung adenocarcinoma (LUAC). I have found that TAp63-null (TAp63-/-) mice exhibit increased susceptibility to UVR-induced cuSCC. To identify TAp63-regulated transcriptional programs relevant to the pathophysiology cuSCC, we performed RNA sequencing of cuSCC and normal tissues from wild-type (WT) and TAp63-/- mice. My data revealed significant perturbations in global miRNA and mRNA expression in TAp63-deficient tumors, which resembled similar transcriptional changes in human cuSCC, including the downregulation of miR-30c-2* and miR-497. Proteomic profiling of cuSCC cell lines and subsequent validation experiments led to the discovery of novel direct targets of miR-497 and miR-30c-2*. The most relevant of these proteins exhibited pro-oncogenic functions, including roles in cell cycle and mitotic progression. My data establishes TAp63 as an essential regulator of miRNA expression during skin carcinogenesis and reveals a previously undescribed network of miRNAs and mRNAs, which include viable, yet previously unexplored targets for therapeutic intervention. Along with TAp63-mediated tumor suppression in the skin, I have also developed a novel TAp73 conditional knockout mouse, which includes a conditional fluorescent reporter (TAp73fltd) that allows us to follow the deletion event at the cellular level. Using this model we have found that the loss of TAp73 accelerates the initiation and progression of oncogenic Krasdriven LUAC. Our data suggests that TAp73 may be necessary for anti-tumor immune responses. In addition, we have found that the loss of TAp73 promotes migration and invasion in human LUAC cell lines. These studies suggest that TAp73 can suppress tumor development and progression through both cell-autonomous and non-cell-autonomous mechanisms. Together, the studies described in this dissertation provide insights into the genetic and epigenetic mechanisms that contribute to cuSCC and LUAC development, which may, in turn, inform future biomarker and drug discovery studies

Genetic algorithms: a pragmatic, non-parametric approach to exploratory analysis of questionnaires in educational research

Data from a survey to determine student attitudes to their courses are used as an example to show how genetic algorithms can be used in the analysis of questionnaire data. Genetic algorithms provide a means of generating logical rules which predict one variable in a data set by relating it to others. This paper explains the principle underlying genetic algorithms and gives a non-mathematical description of the means by which rules are generated. A commercially available computer program is used to apply genetic algorithms to the survey data. The results are discussed

Behavioral conservatism is linked to complexity of behavior in chimpanzees (<i>Pan troglodytes</i>):implications for cognition and cumulative culture

Cumulative culture is rare, if not altogether absent in nonhuman species. At the foundation of cumulative learning is the ability to modify, relinquish, or build upon previous behaviors flexibly to make them more productive or efficient. Within the primate literature, a failure to optimize solutions in this way is often proposed to derive from low-fidelity copying of witnessed behaviors, suboptimal social learning heuristics, or a lack of relevant sociocognitive adaptations. However, humans can also be markedly inflexible in their behaviors, perseverating with, or becoming fixated on, outdated or inappropriate responses. Humans show differential patterns of flexibility as a function of cognitive load, exhibiting difficulties with inhibiting suboptimal behaviors when there are high demands on working memory. We present a series of studies on captive chimpanzees that indicate that behavioral conservatism in apes may be underlain by similar constraints: Chimpanzees showed relatively little conservatism when behavioral optimization involved the inhibition of a well-established but simple solution, or the addition of a simple modification to a well-established but complex solution. In contrast, when behavioral optimization involved the inhibition of a well-established but complex solution, chimpanzees showed evidence of conservatism. We propose that conservatism is linked to behavioral complexity, potentially mediated by cognitive resource availability, and may be an important factor in the evolution of cumulative culture.</p