Molecular Beams

Contains research objectives, summary of research and reports on eight research projects.Joint Services Electronics Programs (U. S. Army, U. S. Navy, and U. S. Air Force) under Contract DAAB07-71-C-030

Early diastolic filling dynamics in diastolic dysfunction

BACKGROUND: The aim of the study was to determine the relationship between the rate of peak early mitral inflow velocity and the peak early diastolic mitral annular tissue velocities in normal controls and to compare them with subjects with diastolic dysfunction. METHODS: The relationship between early passive diastolic transmitral flow and peak early mitral annular velocity in the normal and in diastolic dysfunction was studied. Two groups comprising 22 normal controls and 25 patients with diastolic dysfunction were studied. RESULTS: Compared with the normal group, those with diastolic dysfunction had a lower E/A ratio (0.7 ± 0.2 vs. 1.9 ± 0.5, p < 0.001), a higher time-velocity integral of the atrial component (11.7 ± 3.2 cm vs. 5.5 ± 2.1 cm, p < 0.0001), a longer isovolumic relaxation time 73 ± 12 ms vs. 94 ± 6 ms, p < 0.01 and a lower rate of acceleration of blood across the mitral valve (549.2 ± 151.9 cm/sec(2 )vs. 871 ± 128.1 cm/sec(2), p < 0.001). They also had a lower mitral annular relaxation velocity (Ea) (6.08 ± 1.6 cm/sec vs 12.8 ± 0.67 cm/sec, p < 0.001), which was positively correlated to the acceleration of early diastolic filling (R = 0.66), p < 0.05. CONCLUSIONS: This investigation provides information on the acceleration of early diastolic filling and its relationship to mitral annular peak tissue velocity (Ea) recorded by Doppler tissue imaging. It supports not only the premise that recoil is an important mechanism for rapid early diastolic filling but also the existence of an early diastolic mechanism in normal

Selective Trihydroxylated Azepane Inhibitors of NagZ, a Glycosidase Involved in Pseudomonas Aeruginosa Resistance to β-lactam Antibiotics

The synthesis of a series of D-gluco-like configured 4,5,6-trihydroxyazepanes bearing a triazole, a sulfonamide or a fluorinated acetamide moiety at C-3 is described. These synthetic derivatives have been tested for their ability to selectively inhibit the muropeptide recycling glucosaminidase NagZ and to thereby increase sensitivity of Pseudomonas aeruginosa to β-lactams, a pathway with substantial therapeutic potential. While introduction of triazole and sulfamide groups failed to lead to glucosaminidase inhibitors, the NHCOCF3 analog proved to be a selective inhibitor of NagZ over other glucosaminidases including human OGA and lysosomal hexosaminidases HexA and B. The synthesis of a series of D-gluco-like configured 4,5,6-trihydroxyazepanes bearing a triazole, a sulfonamide or a fluorinated acetamide moiety at C-3 is described. These synthetic derivatives have been tested for their ability to selectively inhibit the muropeptide recycling glucosaminidase NagZ and to thereby increase sensitivity of Pseudomonas aeruginosa to β-lactams, a pathway with substantial therapeutic potential. While introduction of triazole and sulfamide groups failed to lead to glucosaminidase inhibitors, the NHCOCF3 analog proved to be a selective inhibitor of NagZ over other glucosaminidases including human OGA and lysosomal hexosaminidases HexA and B &nbsp

Quantum state preparation and macroscopic entanglement in gravitational-wave detectors

Long-baseline laser-interferometer gravitational-wave detectors are operating at a factor of 10 (in amplitude) above the standard quantum limit (SQL) within a broad frequency band. Such a low classical noise budget has already allowed the creation of a controlled 2.7 kg macroscopic oscillator with an effective eigenfrequency of 150 Hz and an occupation number of 200. This result, along with the prospect for further improvements, heralds the new possibility of experimentally probing macroscopic quantum mechanics (MQM) - quantum mechanical behavior of objects in the realm of everyday experience - using gravitational-wave detectors. In this paper, we provide the mathematical foundation for the first step of a MQM experiment: the preparation of a macroscopic test mass into a nearly minimum-Heisenberg-limited Gaussian quantum state, which is possible if the interferometer's classical noise beats the SQL in a broad frequency band. Our formalism, based on Wiener filtering, allows a straightforward conversion from the classical noise budget of a laser interferometer, in terms of noise spectra, into the strategy for quantum state preparation, and the quality of the prepared state. Using this formalism, we consider how Gaussian entanglement can be built among two macroscopic test masses, and the performance of the planned Advanced LIGO interferometers in quantum-state preparation

Searching for a Stochastic Background of Gravitational Waves with LIGO

The Laser Interferometer Gravitational-wave Observatory (LIGO) has performed the fourth science run, S4, with significantly improved interferometer sensitivities with respect to previous runs. Using data acquired during this science run, we place a limit on the amplitude of a stochastic background of gravitational waves. For a frequency independent spectrum, the new limit is $\Omega_{\rm GW} < 6.5 \times 10^{-5}$. This is currently the most sensitive result in the frequency range 51-150 Hz, with a factor of 13 improvement over the previous LIGO result. We discuss complementarity of the new result with other constraints on a stochastic background of gravitational waves, and we investigate implications of the new result for different models of this background.Comment: 37 pages, 16 figure

Portuguese emigration to Angola (2000-2015): Strengthening a specific postcolonial relationship in a new global framework?

Outflows to the Portuguese-speaking countries, although not dominant, played an important role in the growth of Portuguese emigration during the economic recession and austerity period, between 2010 and 2016. This chapter examines this migration process, considering that contemporary migration from Portugal to Angola is an example of reverse post-colonial migration within the framework of North-South movements. It presents the historical and socio-demographic background of Angola and some theoretical insights on the issue of North-South migration. The analyses of the migration process and the emigrants’ profiles rely in statistics and academic literature but especially on data gathered in a direct survey. Attention is given to indicators of integration, relations with Portugal and the post-colonial nature of the process. The profile of Portuguese in Angola shows an overrepresentation of highly skilled males over 35 years old, which migrated for professional reasons and sustain relations with Portugal through diverse transnational practices. This supports explanations for the emergence of North-South migration by appeal to economic expansion associated to the increasing insertion of several developing countries into global networks. However, the analysis fails to back up the hypothesis that Portuguese emigration to Angola is a form of reverse post-colonial migration based in ancestral return.info:eu-repo/semantics/publishedVersio

Circadian Transcription Contributes to Core Period Determination in Drosophila

The Clock–Cycle (CLK–CYC) heterodimer constitutes a key circadian transcription complex in Drosophila. CYC has a DNA-binding domain but lacks an activation domain. Previous experiments also indicate that most of the transcriptional activity of CLK–CYC derives from the glutamine-rich region of its partner CLK. To address the role of transcription in core circadian timekeeping, we have analyzed the effects of a CYC–viral protein 16 (VP16) fusion protein in the Drosophila system. The addition of this potent and well-studied viral transcriptional activator (VP16) to CYC imparts to the CLK–CYC-VP16 complex strongly enhanced transcriptional activity relative to that of CLK–CYC. This increase is manifested in flies expressing CYC-VP16 as well as in S2 cells. These flies also have increased levels of CLK–CYC direct target gene mRNAs as well as a short period, implicating circadian transcription in period determination. A more detailed examination of reporter gene expression in CYC-VP16–expressing flies suggests that the short period is due at least in part to a more rapid transcriptional phase. Importantly, the behavioral effects require a period (per) promoter and are therefore unlikely to be merely a consequence of generally higher PER levels. This indicates that the CLK–CYC-VP16 behavioral effects are a consequence of increased per transcription. All of this also suggests that the timing of transcriptional activation and not the activation itself is the key event responsible for the behavioral effects observed in CYC-VP16-expressing flies. The results taken together indicate that circadian transcription contributes to core circadian function in Drosophila

Animal Ecosystem Engineers Modulate the Diversity-Invasibility Relationship

Invasions of natural communities by non-indigenous species are currently rated as one of the most important global-scale threats to biodiversity. Biodiversity itself is known to reduce invasions and increase stability. Disturbances by ecosystem engineers affect the distribution, establishment, and abundance of species but this has been ignored in studies on diversity-invasibility relationships.We determined natural plant invasion into 46 plots varying in the number of plant species (1, 4, and 16) and plant functional groups (1, 2, 3, and 4) for three years beginning two years after the establishment of the Jena Experiment. We sampled subplots where earthworms were artificially added and others where earthworm abundance was reduced. We also performed a seed-dummy experiment to investigate the role of earthworms as secondary seed dispersers along a plant diversity gradient. Horizontal dispersal and burial of seed dummies were significantly reduced in subplots where earthworms were reduced in abundance. Seed dispersal by earthworms decreased with increasing plant species richness and presence of grasses but increased in presence of small herbs. These results suggest that dense vegetation inhibits the surface activity of earthworms. Further, there was a positive relationship between the number of earthworms and the number and diversity of invasive plants. Hence, earthworms decreased the stability of grassland communities against plant invasion.Invasibility decreased and stability increased with increasing plant diversity and, most remarkably, earthworms modulated the diversity-invasibility relationship. While the impacts of earthworms were unimportant in low diverse (low earthworm densities) and high diverse (high floral structural complexity) plant communities, earthworms decreased the stability of intermediate diverse plant communities against plant invasion. Overall, the results document that fundamental processes in plant communities like plant seed burial and invader establishment are modulated by soil fauna calling for closer cooperation between soil animal and plant ecologists

Newly identified climatically and environmentally significant high-latitude dust sources

Peer reviewe