10,687 research outputs found
Optimal tracking for pairs of qubit states
In classical control theory, tracking refers to the ability to perform
measurements and feedback on a classical system in order to enforce some
desired dynamics. In this paper we investigate a simple version of quantum
tracking, namely, we look at how to optimally transform the state of a single
qubit into a given target state, when the system can be prepared in two
different ways, and the target state depends on the choice of preparation. We
propose a tracking strategy that is proved to be optimal for any input and
target states. Applications in the context of state discrimination, state
purification, state stabilization and state-dependent quantum cloning are
presented, where existing optimality results are recovered and extended.Comment: 15 pages, 8 figures. Extensive revision of text, optimality results
extended, other physical applications include
Keyframe detection in visual lifelogs
The SenseCam is a wearable camera that passively captures images. Therefore, it requires no conscious effort by a user in taking a photo. A Visual Diary from such a source could prove to be a valuable tool in assisting the elderly, individuals with neurodegenerative diseases, or other traumas. One issue with Visual Lifelogs is the large volume of image data generated. In previous work we spit a day's worth of images into more manageable segments, i.e. into distinct events or activities. However, each event coud stil consist of 80-100 images. thus, in this paper we propose a novel approach to selecting the key images within an event using a combination of MPEG-7 and Scale Invariant Feature Transform (SIFT) features
Explosion of white dwarfs harboring hybrid CONe cores
Recently, it has been found that off-centre carbon burning in a subset of
intermediate-mass stars does not propagate all the way to the center, resulting
in a class of hybrid CONe cores. Here, we consider the possibility that stars
hosting these hybrid CONe cores might belong to a close binary system and,
eventually, become white dwarfs accreting from a non-degenerate companion at
rates leading to a supernova explosion. We have computed the hydrodynamical
phase of the explosion of Chandrasekhar-mass white dwarfs harboring hybrid
cores, assuming that the explosion starts at the center, either as a detonation
(as may be expected in some degenerate merging scenarios) or as a deflagration
(that afterwards transitions into a delayed detonation). We assume these hybrid
cores are made of a central CO volume, of mass M(CO), surrounded by an ONe
shell. We show that, in case of a pure detonation, a medium-sized CO-rich
region, M(CO)<0.4 Msun, results in the ejection of a small fraction of the
mantle while leaving a massive bound remnant. Part of this remnant is made of
the products of the detonation, Fe-group nuclei, but they are buried in its
inner regions, unless convection is activated during the ensuing cooling and
shrinking phase of the remnant. In contrast, and somehow paradoxically, delayed
detonations do not leave remnants but for the minimum M(CO) we have explored,
M(CO)=0.2 Msun, and even in this case the remnant is as small as 0.13 Msun. The
ejecta produced by these delayed detonations are characterized by slightly
smaller masses of 56Ni and substantially smaller kinetic energies than obtained
for a delayed detonation of a 'normal' CO white dwarf. The optical emission
expected from these explosions would hardly match the observational properties
of typical Type Ia supernovae, although they make interesting candidates for
the subluminous class of SN2002cx-like or SNIax.Comment: Accepted for Astronomy and Astrophysics, 11 pages, 4 figure
Cellular and Molecular Mechanisms Driving Glial Engulfment of Degenerating Axons: A Dissertation
The nervous system is made up of two major cell types, neurons and glia. The major distinguishing feature between neuronal cells and glial cells is that neurons are capable of transmitting action potentials while glial cells are electrically incompetent. For over a century glial cells were neglected and it was thought they existed merely to provide trophic and structural support to neurons. However, in the past few decades it has become increasingly clear that glial cell functions underlie almost all aspects of nervous system development, maintenance, and health. During development, glia act as permissive substrates for axons, provide guidance cues, regulate axon bundling, facilitate synapse formation, refine synaptic connections, and promote neuronal survival. In the mature nervous system glial cells regulate adult neurogenesis through phagocytosis, act as the primary immune cell, and contribute to complex processes such as learning and memory. In recent years, glial cells have also become a primary focus in the study of neurodegenerative diseases. Mounting evidence shows that glial cells exert both beneficial as well as detrimental effects in the pathology of several nervous system disorders, and modulation of glial activity is emerging as a viable therapeutic strategy for many diseases. Although glial cells are critical to the proper development and functioning of the nervous system, there is still relatively little known about the molecular mechanisms used by glial cells, how they exert their effects on neurons, and how glia and neurons communicate.
Despite the relative simplicity and small size of the Drosophila nervous system, glial cell organization and function in flies shows a remarkable complexity similar to vertebrate glial cells. In this study I use Drosophila as a model organism to study cellular and molecular mechanisms of glial clearance of axonal debris after acute axotomy. In chapter two of this thesis, I characterize three distinct subtypes of glial cells in the adult brain; cell body glia which ensheath neuronal cell bodies in the cortex region of the brain, astrocyte like glial cells which bear striking morphological similarity to mammalian astrocytes and share common molecular components, and ensheathing glial cells which I show act as the primary phagocytic cell type in the neuropil region of the brain. In addition, I identify dCed-6, the ortholog of mammalian GULP, as a necessary component of the glial phagocytic machinery.
In chapter three of this thesis, I perform a candidate based, in vivo, RNAi screen to identify novel genes involved in the glial engulfment of degenerating axon material. The Gal4/UAS system was used to drive UAS-RNAi for approximately 300 candidate genes with the glial specific repo-Gal4 driver. Two assays were used as a readout in this screen, clearance of axon material five days after injury, and Draper upregulation one day after maxillary palp or antennal injury. Overall, I identified 20 genes which, when knocked down specifically in glial cells, result in axon clearance defects after injury. Finally, in chapter four I identify Stat92E as a novel glial gene required for glial phagocytic function. I show that Stat92E regulates both basal and injury induced Draper expression. Injury-induced Draper expression is transcriptionally regulated through a Stat92E dependent non-canonical signaling mechanism whereby signaling through the Draper receptor activates Stat92E which in turn transcriptionally activates draper through a binding site located in the first intron of Draper. Draper represents only the second receptor known to positively regulate Stat92E transcriptional activity under normal physiological conditions
NDE: A key to engine rotor life prediction
A key ingredient in the establishment of safe life times for critical components is the means of reliably detecting flaws which may potentially exist. Currently used nondestructive evaluation procedures are successful in detecting life limiting defects; however, the development of automated and computer aided NDE technology permits even greater assurance of flight safety
A Missing Link in the Ionoregulatory Strategy of Larval Sea Lamprey (Petromyzon marinus) and African Lungfish (Protopterus annectens): A Closer Look into the Role of the Non-gastric H+/K+-ATPase
Fishes living in freshwater need to actively compensate for the diffusive loss of ions and osmotic gain of water. The gill is the primary organ of ion regulation and contains an array of ion transport proteins to help maintain homeostasis. Two of the more well studied ion pumps are the Na+/K+-ATPase (NKA) and vacuolar type proton ATPase (V-ATPase). This thesis focuses on another ion pump known as the non-gastric H+/K+-ATPase (ngHKA). The ngHKA (gene: atp12a) has not been found in any of the teleost fishes, indicating loss from that lineage. In contrast, there is confirmed expression in lamprey (Petromyzon marinus) and lungfish (Protopterus annectens) and thus these species were used to investigate the role of the ngHKA in fishes. It was hypothesized that the ngHKA plays a role in potassium and/or acid-base regulation in these fishes. The first objective was to develop an antibody as a tool to study the ngHKA. Next, was to characterize tissue expression patterns to infer functional significance. Finally, I wanted to confirm the pump’s functional significance by determining if potassium (fed-fasting) and acid-base challenges (3µEq/g wet mass H+ or HCO3- load) modulate the expression of the ngHKA. The pump was studied at multiple levels including; transcript expression using qPCR, protein expression using Western blotting, localization using immunohistochemistry, as well as potassium and proton ion flux measurements. Rubidium (Rb+) was used as a surrogate flux marker for potassium. The NKA and V-ATPase were also studied in an attempt to understand overall osmoregulation strategies. A rabbit polyclonal antibody (LF12Arb2) was successfully validated for the use in Western blotting and immunohistochemistry in both lamprey and lungfish. High expression of ngHKA was found in both gill and kidney, the major ion regulatory organs in fishes. Rubidium uptake was also successfully measured in both species. In lamprey, fed fish had significantly greater acid uptake and high Rb+ uptake rates against the predictions. Acid loaded lamprey had higher acid excretion rates compared to controls as predicted. There were no differences in ngHKA protein expression for any of the treatments and localization did not appear to change. Transcript (mRNA) levels did not change for any treatments in either lamprey or lungfish. In lungfish, the ngHKA and NKA protein expression decreased in omeprazole treated fish although with no corresponding changes in H+ or Rb+ flux rates. Apical staining did appear more pronounced in the acid loaded fish compared to controls, which should be investigated further. The results show no clear support for the hypothesis that the ngHKA plays a role in potassium and/or acid-base regulation. This was the first study to investigate the ngHKA in fishes. Future studies are suggested to use radioisotopes (86Rb) to advance the methods as well as perform immunohistochemistry quantification analysis
Alien Registration- Doherty, William E. (Calais, Washington County)
https://digitalmaine.com/alien_docs/1220/thumbnail.jp
Women Struggle to Reach the Top: Gender Disparities in the Workplace
Abstract
The study examined the degree to which gender role expectations, anticipated role conflict and same-gendered role models are related to women’s career centrality. It was predicted that women who adhere more to male norms than female norms will indicate more career centrality than women who adhere more to female norms; women who anticipate less work-family conflict will indicate more career centrality; women will identify female role models more often than male role models; and women who identify female role models will report those individuals to have a higher degree of impact on their career centrality. There were 97 students male (19) and female (78) from a single private, Midwestern liberal arts college that participated. Participants completed a survey, in which they responded to items measuring their adherence to male and female norms, items measuring their anticipation of work-family conflict in their future career, one item measuring the degree of impact their identified role model had on their career centrality, and items measuring their career centrality. Findings, revealed women identify female role models more often than they do male role models. The results also reveal a strong positive relationship between reported role model impact and career centrality. Finally, the current study revealed a positive relationship between male norm adherence and career centrality
Inverse Technology Transfer: Development Opportunities Defined from Practice
In the world of technology today, scientists and engineers are concerned about having the results of their work proceed through development to application. This concern exists because of a funding-source pressure to be relevant. One response to this pressure is to become a method evangelist and another is to transfer emphasis from research to technology development. However, a way is available to avoid this unfortunate circumstance and that is to focus on appropriate technology
- …