19,300 research outputs found
Shallow grooves in journal improve air bearing performance
Bearing designs, which shape the surface to create artificial fluid-film wedges in the absence of any applied radial load, generate radial restoring forces to keep journals from whirling. Helical- or herringbone-grooved journals or rotors show most promise of stable operation, with no sacrifice in load capacity
Experimental dynamic stiffness and damping of externally pressurized gas-lubricated journal bearings
A rigid vertical shaft was operated with known amounts of unbalance at speeds to 30,000 rpm and gas supply pressure ratios to 4.8. From measured amplitude and phase angle data, dynamic stiffness and damping coefficients of the bearings were determined. The measured stiffness was proportional to the supply pressure, while damping was little affected by supply pressure. Damping dropped rapidly as the fractional frequency whirl threshold was approached. A small-eccentricity analysis overpredicted the stiffness by 20 to 70 percent. Predicted damping was lower than measured at low speeds but higher at high speeds
The I in Autism:severity and social functioning in Autism is related to self-processing
It is well established that children with autism spectrum disorder (ASD) show impaired understanding of others and deficits within social functioning. However, it is still unknown whether self-processing is related to these impairments and to what extent self impacts social functioning and communication. Using an ownership paradigm, we show that children with ASD and chronological- and verbal-age-matched typically developing (TD) children do show the self-referential effect in memory. In addition, the self-bias was dependent on symptom severity and socio-communicative ability. Children with milder ASD symptoms were more likely to have a high self-bias, consistent with a low attention to others relative to self. In contrast, severe ASD symptoms were associated with reduced self-bias, consistent with an ‘absent-self’ hypothesis. These findings indicate that deficits in self-processing may be related to impairments in social cognition for those on the lower end of the autism spectrum
Experiments on rotating externally pressurized air journal bearings. Part 2 - Attitude angle and air flow
Air flow and attitude angle compared with theory for rotating externally pressurized air journal bearing
Chromosome 9p deletion in clear cell renal cell carcinoma predicts recurrence and survival following surgery
BACKGROUND: Wider clinical applications of 9p status in clear cell renal cell carcinoma (ccRCC) are limited owing to the lack of validation and consensus for interphase fluorescent in situ hybridisation (I-FISH) scoring technique. The aim of this study was to analytically validate the applicability of I-FISH in assessing 9p deletion in ccRCC and to clinically assess its long-term prognostic impact following surgical excision of ccRCC. METHODS: Tissue microarrays were constructed from 108 renal cell carcinoma (RCC) tumour paraffin blocks. Interphase fluorescent in situ hybridisation analysis was undertaken based on preset criteria by two independent observers to assess interobserver variability. 9p status in ccRCC tumours was determined and correlated to clinicopathological variables, recurrence-free survival and disease-specific survival. RESULTS: There were 80 ccRCCs with valid 9p scoring and a median follow-up of 95 months. Kappa statistic for interobserver variability was 0.71 (good agreement). 9p deletion was detected in 44% of ccRCCs. 9p loss was associated with higher stage, larger tumours, necrosis, microvascular and renal vein invasion, and higher SSIGN (stage, size, grade and necrosis) score. Patients with 9p-deleted ccRCC were at a higher risk of recurrence (P=0.008) and RCC-specific mortality (P=0.001). On multivariate analysis, 9p deletion was an independent predictor of recurrence (hazard ratio 4.323; P=0.021) and RCC-specific mortality (hazard ratio 4.603; P=0.007). The predictive accuracy of SSIGN score improved from 87.7% to 93.1% by integrating 9p status to the model (P=0.001). CONCLUSIONS: Loss of 9p is associated with aggressive ccRCC and worse prognosis in patients following surgery. Our findings independently confirm the findings of previous reports relying on I-FISH to detect 9p (CDKN2A) deletion
Opioid modulation of GABA release in the rat inferior colliculus
Background: The inferior colliculus, which receives almost all ascending and descending auditory signals, plays a crucial role in the processing of auditory information. While the majority of the recorded activities in the inferior colliculus are attributed to GABAergic and glutamatergic signalling, other neurotransmitter systems are expressed in this brain area including opiate peptides and their receptors which may play a modulatory role in neuronal communication.Results: Using a perfusion protocol we demonstrate that morphine can inhibit KCl-induced release of [H-3] GABA from rat inferior colliculus slices. DAMGO ([D-Ala(2), N-Me-Phe(4), Gly(5)ol]-enkephalin) but not DADLE ([D-Ala2, D-Leu5]-enkephalin or U69593 has the same effect as morphine indicating that mu rather than delta or kappa opioid receptors mediate this action. [H-3]GABA release was diminished by 16%, and this was not altered by the protein kinase C inhibitor bisindolylmaleimide I. Immunostaining of inferior colliculus cryosections shows extensive staining for glutamic acid decarboxylase, more limited staining for mu opiate receptors and relatively few neurons co-stained for both proteins.Conclusion: The results suggest that mu-opioid receptor ligands can modify neurotransmitter release in a sub population of GABAergic neurons of the inferior colliculus. This could have important physiological implications in the processing of hearing information and/or other functions attributed to the inferior colliculus such as audiogenic seizures and aversive behaviour
Primary Production and Carbon Allocation in Creosotebush: the Effect of Carbohydrate Levels on Dark CO2 Release
Single-electron transport driven by surface acoustic waves: moving quantum dots versus short barriers
We have investigated the response of the acoustoelectric current driven by a
surface-acoustic wave through a quantum point contact in the closed-channel
regime. Under proper conditions, the current develops plateaus at integer
multiples of ef when the frequency f of the surface-acoustic wave or the gate
voltage Vg of the point contact is varied. A pronounced 1.1 MHz beat period of
the current indicates that the interference of the surface-acoustic wave with
reflected waves matters. This is supported by the results obtained after a
second independent beam of surface-acoustic wave was added, traveling in
opposite direction. We have found that two sub-intervals can be distinguished
within the 1.1 MHz modulation period, where two different sets of plateaus
dominate the acoustoelectric-current versus gate-voltage characteristics. In
some cases, both types of quantized steps appeared simultaneously, though at
different current values, as if they were superposed on each other. Their
presence could result from two independent quantization mechanisms for the
acoustoelectric current. We point out that short potential barriers determining
the properties of our nominally long constrictions could lead to an additional
quantization mechanism, independent from those described in the standard model
of 'moving quantum dots'.Comment: 25 pages, 12 figures, to be published in a special issue of J. Low
Temp. Phys. in honour of Prof. F. Pobel
Strategic Network Formation with Attack and Immunization
Strategic network formation arises where agents receive benefit from
connections to other agents, but also incur costs for forming links. We
consider a new network formation game that incorporates an adversarial attack,
as well as immunization against attack. An agent's benefit is the expected size
of her connected component post-attack, and agents may also choose to immunize
themselves from attack at some additional cost. Our framework is a stylized
model of settings where reachability rather than centrality is the primary
concern and vertices vulnerable to attacks may reduce risk via costly measures.
In the reachability benefit model without attack or immunization, the set of
equilibria is the empty graph and any tree. The introduction of attack and
immunization changes the game dramatically; new equilibrium topologies emerge,
some more sparse and some more dense than trees. We show that, under a mild
assumption on the adversary, every equilibrium network with agents contains
at most edges for . So despite permitting topologies denser
than trees, the amount of overbuilding is limited. We also show that attack and
immunization don't significantly erode social welfare: every non-trivial
equilibrium with respect to several adversaries has welfare at least as that of
any equilibrium in the attack-free model.
We complement our theory with simulations demonstrating fast convergence of a
new bounded rationality dynamic which generalizes linkstable best response but
is considerably more powerful in our game. The simulations further elucidate
the wide variety of asymmetric equilibria and demonstrate topological
consequences of the dynamics e.g. heavy-tailed degree distributions. Finally,
we report on a behavioral experiment on our game with over 100 participants,
where despite the complexity of the game, the resulting network was
surprisingly close to equilibrium.Comment: The short version of this paper appears in the proceedings of WINE-1
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