Nonlinear Interactions Between Gravitational Radiation and Modified Alfven Modes in Astrophysical Dusty Plasmas

We present an investigation of nonlinear interactions between Gravitational Radiation and modified Alfv\'{e}n modes in astrophysical dusty plasmas. Assuming that stationary charged dust grains form neutralizing background in an electron-ion-dust plasma, we obtain the three wave coupling coefficients, and calculate the growth rates for parametrically coupled gravitational radiation and modified Alfv\'{e}n-Rao modes. The threshold value of the gravitational wave amplitude associated with convective stabilization is particularly small if the gravitational frequency is close to twice the modified Alfv\'en wave-frequency. The implication of our results to astrophysical dusty plasmas is discussed.Comment: A few typos corrected. Published in Phys. Rev.

Video head impulse testing: Pitfalls in neurological patients

The video head impulse test (vHIT) assesses the vestibulo-ocular reflex (VOR) during a rapid high-velocity low amplitude (10°–20°) head rotation. Patients with peripheral vestibulopathy have a reduced VOR gain with corrective catch-up saccades during the head turn. There are several pitfalls, mainly technical, which may interfere with interpretation of vHIT data. In addition, intrusive eye movement disorders such as spontaneous nystagmus that affect normal eye position and tracking can affect the vHIT results. To date there has been little study of neurological saccadic eye movements that may interfere with the interpretation of vHIT data. Here, in ten patients with a range of central neurological disorders, we describe oculomotor abnormalities on vHIT in the presence of normal range VOR gain values, recorded at a tertiary vestibular neurology service

Eosinophils and Oral Squamous Cell Carcinoma: A Short Review

The eosinophil cell has been related as a prognostic indicator for cancers. However, its exact function in tumour behaviour is still not clearly defined. In the oral cavity the presence of eosinophils can be a favourable prognostic indicator as well as it may be associated with a poor prognosis. In this short review, we briefly summarize the role of the eosinophils in the general context of immunoregulation and its relation to oral squamous cell carcinoma

In situ synchrotron radiation diffraction investigation of the compression behaviour at 350 °C of ZK40 alloys with addition of CaO and Y

The evolution of the microstructure during compression is investigated with in situ synchrotron radiation diffraction in as-cast ZK40, ZK40-2CaO and ZK40-1Y Mg alloys. The specimens were compressed at 350 °C with a strain rate of 10−3 s−1 until 30% deformation. The Y containing alloy showed the highest 0.2% proof strength in compression of 35 MPa at 350 °C which is double that of the ZK40 alloy, while the CaO added alloy shows a moderate increment at 23 MPa. The Y containing alloy shows some work hardening, while the CaO modified and the ZK40 alloys do not show work hardening after yield. Synchrotron radiation diffraction timelines show that continuous and discontinuous dynamic recrystallization occurs during deformation of the ZK40 alloy while a small amount of dynamic recrystallization was observed in the ZK40-1Y alloy. However, dynamic recrystallization was not present in the ZK40-2CaO alloy. SEM-EBSD analysis conducted on the deformed samples shows a significantly high volume fraction of twins in the Y and CaO containing alloys which was absent in the ZK40 alloy. The modified deformation behaviours observed in the CaO and Y containing alloys were attributed to the presence of intermetallic particles found at the grain boundaries and to the role of Ca and Y in stabilising twinning.The authors acknowledge the Deutsches Elektronen-Synchro-tron for the provision of facilities within the framework of proposal I-20130434.RHBacknowledgesUniversityofSãoPaulofor granting the fellowship 'Bolsa Empreendedorismo'

New Methods for Palladium-catalyzed Decarboxylative Benzylation, Arylation and Dearomatization Reactions

Development of novel synthetic methods for the efficient generation of new carbon-carbon bonds is a valuable endeavor in organic synthesis. In this regard, palladium-catalyzed decarboxylative cross-coupling has significant potential as a waste-free reaction manifold with increased functional group tolerance due to the avoidance of preformed organometallics and basic reagents. Since the initial reports by Saegusa and Tsuji on decarboxylative allylation (DcA) of β-ketoesters in 1980, this concept remained relatively unexplored until the independent reports from Tunge and Stoltz in 2004. Since then, couplings of a broad array of nucleophiles, as well as asymmetric variants of the DcA reactions, have been heavily developed. However, due to the inherently low reactivity of benzyl electrophiles, catalytic decarboxylative benzylation reactions are comparatively less developed. Presented herein are the developments of new methods for the catalytic decarboxylative benzylic cross-coupling reactions with weakly-stabilized nucleophiles. In particular, the benzyl alkyne cross-coupling, which was initially limited to extended aryl systems, was further developed to allow couplings of primary benzyl electrophiles without extended π-conjugation. Our efforts were then directed toward developing a highly stereospecific decarboxylative coupling of acetylides and ketone enolates with secondary benzyl electrophiles that possess a 1,1-diarylmethane structure. The coupling of secondary benzyl electrophiles with acetylides proceeded with high stereospecificity to provide enantioenriched 1,1-diarylethynyl methanes, and we are unaware of any other method for the direct synthesis of such motifs. However, racemization was observed in the decarboxylative coupling of enantioenriched benzylic β-ketoesters. In the search for a new method to couple secondary benzyl electrophiles with ketone enolates, we serendipitously discovered the unprecedented catalytic decarboxylative dearomatization and arylation reactions of ketone enolates. Two sets of protocols involving simple variation of ligands were then developed for the selective decarboxylative dearomatization or arylation of enolates. These methods provided alicyclic and mono-α-arylated ketones in a highly regioselective manner and the expected benzylation of ketone enolates was never observed. Additionally, initial results have also shown that the palladium-catalyzed decarboxylative dearomatization of benzyl carbonates is highly stereospecific

The effect of thermophoresis on the discharge parameters in complex plasma experiments

Thermophoresis is a tool often applied in complex plasma experiments. One of the usual stated benefits over other experimental tools is that changes induced by thermophoresis neither directly depend on, nor directly influence, the plasma parameters. From electronic data, plasma emission profiles in the sheath, and Langmuir probe data in the plasma bulk, we conclude that this assumption does not hold. An important effect on the levitation of dust particles in argon plasma is observed as well. The reason behind the changes in plasma parameters seems to be the change in neutral atom density accompanying the increased gas temperature while running at constant pressure.Comment: 14 pages, 12 figure

Seismic performance of super tall buildings

With the rapid population growth and dynamic economic developments, the demand for residential, mixed use and commercial buildings has been increasing significantly all around the world. Due to the excessive increase in height of buildings in this era, there is a significant impact on the methods used to analyze and design of tall buildings. There is a clear acceptance within the engineering community that the specifications given in codes of practice are not suitable for very tall buildings. General concepts, current methods of analysis and seismic performance of super tall buildings are reviewed in this paper. Further the effect of higher modes on the performance of super tall buildings is also discussed