5,882 research outputs found
A secure additive protocol for card players
Consider three players Alice, Bob and Cath who hold a, b and c cards,
respectively, from a deck of d=a+b+c cards. The cards are all different and
players only know their own cards. Suppose Alice and Bob wish to communicate
their cards to each other without Cath learning whether Alice or Bob holds a
specific card.
Considering the cards as consecutive natural numbers 0,1,..., we investigate
general conditions for when Alice or Bob can safely announce the sum of the
cards they hold modulo an appropriately chosen integer. We demonstrate that
this holds whenever a,b>2 and c=1. Because Cath holds a single card, this also
implies that Alice and Bob will learn the card deal from the other player's
announcement
A Triangular Tessellation Scheme for the Adsorption Free Energy at the Liquid-Liquid Interface: Towards Non-Convex Patterned Colloids
We introduce a new numerical technique, namely triangular tessellation, to
calculate the free energy associated with the adsorption of a colloidal
particle at a flat interface. The theory and numerical scheme presented here
are sufficiently general to handle non-convex patchy colloids with arbitrary
surface patterns characterized by a wetting angle, e.g., amphiphilicity. We
ignore interfacial deformation due to capillary, electrostatic, or
gravitational forces, but the method can be extended to take such effects into
account. It is verified that the numerical method presented is accurate and
sufficiently stable to be applied to more general situations than presented in
this paper. The merits of the tessellation method prove to outweigh those of
traditionally used semi-analytic approaches, especially when it comes to
generality and applicability.Comment: 21 pages, 11 figures, 0 table
Pudendal nerve stimulation induces urethral contraction and relaxation
In this study we measured urethral pressure changes in response to
efferent pudendal nerve stimulation in rats. All other neural pathways to
the urethra were transected, and the urethra was continuously perfused. We
found fast twitch-like contractions, superimposed on a slow relaxation.
The amplitude of the twitches was independent of the stimulation frequency
below 26 Hz, whereas the relaxation depended highly on this frequency. The
twitches were caused by striated urethral muscles, and the relaxation was
caused by smooth muscles. Both were mediated by acetylcholine. We
calculated the effective urethral relaxation as the absolute relaxation
multiplied by the time fraction between the twitches. Maximum effective
relaxation occurred at 8-10 Hz, exactly the frequency of spontaneous
oscillations during bladder voiding in rats. Although the oscillatory
sphincter contractions in rats during voiding may be needed in other
mechanisms for efficient voiding, our data suggest that they may be a side
effect of the actual purpose: urethral relaxation
Cutaneous pathology in primary erythermalgia
Primary or idiopathic erythermalgia is characterized by recurrent, red, warm, and painful lower extremities. It arises at young age and persists throughout life because no treatment is available. We report the cutaneous pathology of affected skin lesions of three patients with primary erythermalgia. Biopsy specimens showed a mild perivascular mononuclear infiltrate, thickened blood vessel basement membranes, abundant perivascular edema, and moderate endothelial swelling. The thickened basal membrane of the blood vessels showed a laminar structure, and abundant perivascular edema and moderate endothelial cell swelling were evident. These histopathologic findings in primary erythermalgia appear to be nonspecific but allow diagnostic differentiation from erythromelalgia in which fibromuscular intimal proliferation and occlusive thrombi in the endarteriolar capillaries are apparent and from erythermalgia secondary to vasculitis. Histopathologic examination of affected skin lesions in patients with red, congested, warm, and painful burning extremities is a valuable tool in the diagnostic process
Neurophysiological modeling of voiding in rats: urethral nerve response to urethral pressure and flow
In male urethan-anesthetized rats, activity was measured in nerves that
run over the proximal urethra. The urethral nerve response to stepwise
urethral perfusion could be described by a four-parameter model (fit error
< 6%). At the onset of perfusion, the urethra was closed and the pressure
increased with the infused volume. The nerve activity (NA) increased
linearly with this inserted volume to a maximum (NAmax), which was
proportional to the instantaneous pressure. The duration of this first
episode (delta t) was inversely proportional to the perfusion rate. After
infusion of a fixed volume, the urethra opened and the NA decreased with a
time constant phi -1 (approximately 1.8 s) to an elevated level (NAlevel).
NAlevel was linearly related to the steady-state pressure. Accordingly,
sensors in the urethra are sensitive to pressure rather than to the
perfusion rate. The parameters NAmax, NAlevel, and delta t showed very
good reproducibility (SD approximately 19% of mean). The measured activity
was most likely afferent and conducted to the major pelvic ganglion
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