Probing the Structure, Pseudorotation, and Radial Vibrations of Cyclopentane by Femtosecond Rotational Raman Coherence Spectroscopy

Femtosecond time-resolved Raman rotational coherence spectroscopy (RCS) is employed to determine accurate rotational, vibration–rotation coupling constants, and centrifugal distortion constants of cyclopentane (C⁵H¹⁰). Its lowest-frequency vibration is a pseudorotating ring deformation that interconverts 10 permutationally distinct but energetically degenerate “twist” minima interspersed by 10 “bent” conformers. While the individual twist and bent structures are polar asymmetric tops, the pseudorotation is fast on the time scale of external rotation, rendering cyclopentane a fluxionally nonpolar symmetric top molecule. The pseudorotational level pattern corresponds to a one-dimensional internal rotor with a pseudorotation constant Bps ≈ 2.8 cm⁻¹. The pseudorotational levels are significantly populated up to l = ± 13 at 298 K; <10% of the molecules are in the l = 0 level. The next-higher vibration is the “radial” ν²³ ring deformation mode at 273 cm⁻¹, which is far above the pseudorotational fundamental. Femtosecond Raman RCS measurements were performed in a gas cell at T = 293 K and in a pulsed supersonic jet at T ≈ 90 K. The jet cooling reduces the pseudorotational distribution to l < ±8 and eliminates the population of ν²³, allowing one to determine the rotational constant as A0 = B0 = 6484.930(11) MHz. This value is ∼300 times more precise than the previous value. The fit of the RCS transients reveals that the rotation–pseudorotation coupling constant αe,psB = −0.00070(1) MHz is diminutive, implying that excitation of the pseudorotation has virtually no effect on the B0 rotational constant of cyclopentane. The smallness of αe,psB can be realized when comparing to the vibration–rotation coupling constant of the ν²³ vibration, αe,23B = −9.547(1) MHz, which is about 10⁴ times larger.

Measurement and correlates of physical activity behavior among older minority women

Research has shown that physical activity serves a preventive function against the development of several major chronic diseases. However, studying physical activity and its health benefits is difficult due to the complexity of measuring physical activity. The overall aim of this research is to contribute to the knowledge of both correlates and measurement of physical activity. Data from the Women On The Move study were used for this study (n = 260), and the results are presented in three papers. The first paper focuses on the measurement of physical activity and compares an alternate coding method with the standard coding method for calculating energy expenditure from a 7-day activity diary. Results indicate that the alternative coding scheme could produce similar results to the standard coding in terms of total activity expenditure. Even though agreement could not be achieved by dimension, the study lays the groundwork for a coding system that saves considerable amount of time in coding activity and has the ability to estimate expenditure more accurately for activities that can be performed at varying intensity levels. The second paper investigates intra-day variability in physical activity by estimating the variation in energy expenditure for workers and non-workers and identifying the number of days of diary self-report necessary to reliably estimate activity. The results indicate that 8 days of activity are needed to reliably estimate total activity for individuals who don't work and 12 days of activity are needed to reliably estimate total activity for those who work. Days of diary self-report required by dimension for those who don't work range from 6 to 16 and for those who work from 6 to 113. The final paper presents findings on the relationship between daily living activity and Type A behavior pattern. Significant findings are observed for total activity and leisure activity with the Temperament Scale summary score. Significant findings are also observed for total activity, household chores, work, leisure activity, exercise, and inactivity with one or more of the individual items on the Temperament Scale. However, even though some significant findings were observed, the overall models did not reveal meaningful associations. ^

Roles of mismatch repair proteins in the recognition and processing of DNA interstrand crosslinks in human cells

DNA interstrand crosslinks (ICLs) are among the most toxic type of damage to a cell. Many ICL-inducing agents are widely used as therapeutic agents, e.g. cisplatin, psoralen. A bettor understanding of the cellular mechanism that eliminates ICLs is important for the improvement of human health. However, ICL repair is still poorly understood in mammals. Using a triplex-directed site-specific ICL model, we studied the roles of mismatch repair (MMR) proteins in ICL repair in human cells. We are also interested in using psoralen-conjugated triplex-forming oligonucleotides (TFOs) to direct ICLs to a specific site in targeted DNA and in the mammalian genomes. ^ MSH2 protein is the common subunit of two MMR recognition complexes, and MutSα and MutSβ. We showed that MSH2 deficiency renders human cell hypersensitive to psoralen ICLs. MMR recognition complexes bind specifically to triplex-directed psoralen ICLs in vitro. Together with the fact that psoralen ICL-induced repair synthesis is dramatically decreased in MSH2 deficient cell extracts, we demonstrated that MSH2 function is critical for the recognition and processing of psoralen ICLs in human cells. Interestingly, lack of MSH2 does not reduce the level of psoralen ICL-induced mutagenesis in human cells, suggesting that MSH2 does not contribute to error-generating repair of psoralen ICLs, and therefore, may represent a novel error-free mechanism for repairing ICLs. We also studied the role of MLH1, anther key protein in MMR, in the processing of psoralen ICLs. MLH1-deficient human cells are more resistant to psoralen plus UVA treatment. Importantly, MLH1 function is not required for the mutagenic repair of psoralen ICLs, suggesting that it is not involved in the error-generating repair of this type of DNA damage in human cells. ^ These are the first data indicating mismatch repair proteins may participate in a relatively error-free mechanism for processing psoralen ICL in human cells. Enhancement of MMR protein function relative to nucleotide excision repair proteins may reduce the mutagenesis caused by DNA ICLs in humans. ^ In order to specifically target ICLs to mammalian genes, we identified novel TFO target sequences in mouse and human genomes. Using this information, many critical mammalian genes can now be targeted by TFOs.^

Measurement and characterization of interoperability between devices with SpaceWire communications

This Master Final Project is intended to show the process developed to the functional and electrical characterization between different devices that use the SpaceWire space communications standard integrated into an evaluation board designed for this purpose. In order to carry out this characterization, firstly, a study to understand the SpaceWire standard is done. After that, another study for the understanding of the demonstration board with its different interfaces and IPs of SpW is done. According to this, it is expected to find out how the SpW devices are structured, especially at FPGA level, and how is the communication between them. Based on the knowledge obtained about SpaceWire and the SpW devices integrated into the evaluation board, the set of measurements and the strategy to validate electrical interoperability between the different devices are defined, as well as to perform functional checks required to ensure its proper understanding. Furthermore, it will let check whether the standard is met and search the limit of operation within a communication system representative of existing equipment in a satellite. Once finished the test plan and implemented on the representative hardware, the board will be considered characterized at SpW level and a report with the conclusions reached about the operation of the SpW interfaces in the board and constraints found will be done. RESUMEN. El presente Trabajo Fin de Máster pretende mostrar el proceso realizado para la caracterización eléctrica y funcional entre distintos dispositivos que utilizan el estándar de comunicaciones espaciales SpaceWire integrados en una tarjeta de evaluación diseñada para tal efecto. Para poder llevar a cabo dicha caracterización, en primer lugar, se realiza un estudio para el conocimiento del estándar SpaceWire. A continuación, se lleva a cabo otro estudio para el conocimiento de la tarjeta de demostración en la que se encuentran los distintos interfaces e IPs de SpW. Con esto último, se pretende conocer como están estructurados los dispositivos SpW, sobre todo a nivel de FPGA, y como se realiza la comunicación entre ellos. En base a los conocimientos adquiridos acerca de SpaceWire y los dispositivos SpW de la tarjeta de evaluación, se definen el conjunto de medidas y la estrategia a seguir para validar eléctricamente la interoperabilidad entre los distintos dispositivos, así como para realizar las comprobaciones funcionales necesarias para asegurar su correcto entendimiento. Además, con ello se podrá comprobar si se cumple el estándar y se podrá también buscar el límite de operación dentro de un sistema de comunicaciones representativo de los equipos existentes en un satélite. Realizado el plan de pruebas y aplicado sobre el hardware representativo se podrá dar por caracterizada la tarjeta a nivel SpW y realizar un informe con las conclusiones alcanzadas acerca del funcionamiento de los interfaces SpW de la tarjeta y las limitaciones encontradas.

Drifting plasma collection by a positive biased tether wire in LEO-like plasma conditions: current measurement and plasma diagnostic

BETs is a three-year project financed by the Space Program of the European Commission, aimed at developing an efficient deorbit system that could be carried on board any future satellite launched into Low Earth Orbit (LEO). The operational system involves a conductive tape-tether left bare to establish anodic contact with the ambient plasma as a giant Langmuir probe. As a part of this project, we are carrying out both numerical and experimental approaches to estimate the collected current by the positive part of the tether. This paper deals with experimental measurements performed in the IONospheric Atmosphere Simulator (JONAS) plasma chamber of the Onera-Space Environment Department. The JONAS facility is a 9- m3 vacuum chamber equipped with a plasma source providing drifting plasma simulating LEO conditions in terms of density and temperature. A thin metallic cylinder, simulating the tether, is set inside the chamber and polarized up to 1000 V. The Earth's magnetic field is neutralized inside the chamber. In a first time, tether collected current versus tether polarization is measured for different plasma source energies and densities. In complement, several types of Langmuir probes are used at the same location to allow the extraction of both ion densities and electron parameters by computer modeling (classical Langmuir probe characteristics are not accurate enough in the present situation). These two measurements permit estimation of the discrepancies between the theoretical collection laws, orbital motion limited law in particular, and the experimental data in LEO-like conditions without magnetic fields. In a second time, the spatial variations and the time evolutions of the plasma properties around the tether are investigated. Spherical and emissive Langmuir probes are also used for a more extensive characterization of the plasma in space and time dependent analysis. Results show the ion depletion because of the wake effect and the accumulation of- ions upstream of the tether. In some regimes (at large positive potential), oscillations are observed on the tether collected current and on Langmuir probe collected current in specific sites.

Molecular cloning, sequence, expression, and processing of the interleukin 16 precursor

Interleukin 16 (IL-16) has been shown to function as chemoattractant factor, as a modulator of T-cell activation, and as an inhibitor of immunodeficiency virus replication. The recent identification of inconsistencies in published IL-16 cDNA nucleotide sequences led to the proposal that IL-16 is synthesized in the form of a large precursor protein (pro-IL-16). To identify the true transcriptional start of the IL-16 mRNA rapid amplification of cDNA ends methods were applied. The complete pro-IL-16 cDNA was subsequently molecularly cloned, sequenced, and expressed in COS-7 cells. We report here that pro-IL-16 is most likely synthesized as a 67-kDa protein and is encoded from a major 2.6-kb transcript. Recombinant pro-IL-16 polypeptides are specifically cleaved in lysates of CD8(+) cells, suggesting that the naturally secreted bioactive form of IL-16 is smaller than the originally published 130 amino acids fragment. Moreover, in contrast to other interleukins such as IL-15, IL-16 mRNA expression is almost exclusively limited to lymphatic tissues underlining the potential of IL-16 as an immune regulatory molecule.

Assembly of the Nuclear Transcription and Processing Machinery: Cajal Bodies (Coiled Bodies) and Transcriptosomes

We have examined the distribution of RNA transcription and processing factors in the amphibian oocyte nucleus or germinal vesicle. RNA polymerase I (pol I), pol II, and pol III occur in the Cajal bodies (coiled bodies) along with various components required for transcription and processing of the three classes of nuclear transcripts: mRNA, rRNA, and pol III transcripts. Among these components are transcription factor IIF (TFIIF), TFIIS, splicing factors, the U7 small nuclear ribonucleoprotein particle, the stem–loop binding protein, SR proteins, cleavage and polyadenylation factors, small nucleolar RNAs, nucleolar proteins that are probably involved in pre-rRNA processing, and TFIIIA. Earlier studies and data presented here show that several of these components are first targeted to Cajal bodies when injected into the oocyte and only subsequently appear in the chromosomes or nucleoli, where transcription itself occurs. We suggest that pol I, pol II, and pol III transcription and processing components are preassembled in Cajal bodies before transport to the chromosomes and nucleoli. Most components of the pol II transcription and processing pathway that occur in Cajal bodies are also found in the many hundreds of B-snurposomes in the germinal vesicle. Electron microscopic images show that B-snurposomes consist primarily, if not exclusively, of 20- to 30-nm particles, which closely resemble the interchromatin granules described from sections of somatic nuclei. We suggest the name pol II transcriptosome for these particles to emphasize their content of factors involved in synthesis and processing of mRNA transcripts. We present a model in which pol I, pol II, and pol III transcriptosomes are assembled in the Cajal bodies before export to the nucleolus (pol I), to the B-snurposomes and eventually to the chromosomes (pol II), and directly to the chromosomes (pol III). The key feature of this model is the preassembly of the transcription and processing machinery into unitary particles. An analogy can be made between ribosomes and transcriptosomes, ribosomes being unitary particles involved in translation and transcriptosomes being unitary particles for transcription and processing of RNA.

Subdivisions of auditory cortex and processing streams in primates

The auditory system of monkeys includes a large number of interconnected subcortical nuclei and cortical areas. At subcortical levels, the structural components of the auditory system of monkeys resemble those of nonprimates, but the organization at cortical levels is different. In monkeys, the ventral nucleus of the medial geniculate complex projects in parallel to a core of three primary-like auditory areas, AI, R, and RT, constituting the first stage of cortical processing. These areas interconnect and project to the homotopic and other locations in the opposite cerebral hemisphere and to a surrounding array of eight proposed belt areas as a second stage of cortical processing. The belt areas in turn project in overlapping patterns to a lateral parabelt region with at least rostral and caudal subdivisions as a third stage of cortical processing. The divisions of the parabelt distribute to adjoining auditory and multimodal regions of the temporal lobe and to four functionally distinct regions of the frontal lobe. Histochemically, chimpanzees and humans have an auditory core that closely resembles that of monkeys. The challenge for future researchers is to understand how this complex system in monkeys analyzes and utilizes auditory information.