2,397 research outputs found
"Murderers of the Dead" in Antiphon 1
Includes bibliographical references.The anonymous speaker of Antiphon 1 is prosecuting his stepmother for the murder of his father. Yet, in his prooemium and prokataskeue, he exerts more effort to discredit his stepmother's defenders (i.e., his half-brothers ...) than to attack the defendant. He even makes the surprising allegation that his half-brothers are "murderers of the dead man" ... even though, according to the prosecutor's own admission, his father died as a result of potion acquired by the stepmother but administered by an unwitting slave woman (1.14-20).1 The phrase "murderers of the dead man" is paradoxical, for how can someone become the murderer of a man who is already dead at the hands of someone else? Even if we use the translation "murderers of the victim," some sense of paradox remains to catch our attention. Why does Antiphon have the prosecutor include such an allegation? Would it surprise Athenian jurors, or is it merely a topos or a feature of Antiphon's style? To the contrary, as an examination of some of the prosecutor's options and tactics will show, this accusation reveals a crucial element of his strategy.--Page 1
The Mason Test: A Defense Against Sybil Attacks in Wireless Networks Without Trusted Authorities
Wireless networks are vulnerable to Sybil attacks, in which a malicious node
poses as many identities in order to gain disproportionate influence. Many
defenses based on spatial variability of wireless channels exist, but depend
either on detailed, multi-tap channel estimation - something not exposed on
commodity 802.11 devices - or valid RSSI observations from multiple trusted
sources, e.g., corporate access points - something not directly available in ad
hoc and delay-tolerant networks with potentially malicious neighbors. We extend
these techniques to be practical for wireless ad hoc networks of commodity
802.11 devices. Specifically, we propose two efficient methods for separating
the valid RSSI observations of behaving nodes from those falsified by malicious
participants. Further, we note that prior signalprint methods are easily
defeated by mobile attackers and develop an appropriate challenge-response
defense. Finally, we present the Mason test, the first implementation of these
techniques for ad hoc and delay-tolerant networks of commodity 802.11 devices.
We illustrate its performance in several real-world scenarios
Characterization of a 14 kDa oocyst wall protein of Eimeria tenella and E. acervulina
We have extracted a protein of 14 kDa from purified oocyst walls of several Eimeria species. Polyclonal antibodies were raised in rats against the 14 kDa proteins of E. acervulina and E. tenella. On immunoblots these antisera reacted in a highly specific manner with the homologous 14 kDa antigens, but not with heterologous antigens. In addition, specific binding of the two antisera to oocyst wall fragments of E. acervulina and E. tenella was demonstrated by immunofluorescence. Partial amino-terminal sequences comprising 20 amino acid residues were obtained from the 14 kDa oocyst wall proteins of E. acervulina and E. tenella. They are characterized by an abundance of amino acids containing hydroxyl groups in their side chains (serine, tyrosine, threonine). Binding of the oocyst wall protein of E. tenella by peanut agglutinin indicates the presence of O-linked carbohydrate
On the dimension of subspaces with bounded Schmidt rank
We consider the question of how large a subspace of a given bipartite quantum
system can be when the subspace contains only highly entangled states. This is
motivated in part by results of Hayden et al., which show that in large d x
d--dimensional systems there exist random subspaces of dimension almost d^2,
all of whose states have entropy of entanglement at least log d - O(1). It is
also related to results due to Parthasarathy on the dimension of completely
entangled subspaces, which have connections with the construction of
unextendible product bases. Here we take as entanglement measure the Schmidt
rank, and determine, for every pair of local dimensions dA and dB, and every r,
the largest dimension of a subspace consisting only of entangled states of
Schmidt rank r or larger. This exact answer is a significant improvement on the
best bounds that can be obtained using random subspace techniques. We also
determine the converse: the largest dimension of a subspace with an upper bound
on the Schmidt rank. Finally, we discuss the question of subspaces containing
only states with Schmidt equal to r.Comment: 4 pages, REVTeX4 forma
Renewable Ammonia
Ammonia is one of the most widely used chemicals that is commercially produced today given the wide need for fertilizer to sustain the world’s ever-growing populations. Given the high world demand for ammonia, which increases every day, one can see how beneficial to the environment that a zero emission large-scale ammonia plant would be. Through the use of energy from Norwegian wind farms, which produce an excess of energy during off-peak hours, our plant design seeks to turn this wasted energy into useful ammonia products at a production rate of 67.2 kmol/hr.
The design of this ammonia synthesis plant can be split conceptually into two distinct halves. The first is the refinement of the hydrogen and nitrogen that are required for the Haber-Bosch synthesis from the raw inputs of air and water. This is done through the usage of solid oxide electrolytic cells which electrolyze the water into constituent hydrogen and oxygen atoms and separate the oxygen out of the air. The second half of the plant design is a typical Haber-Bosch ammonia synthesis that many plants today are utilizing. This section consists mainly of a reaction vessel at the correct operating conditions for the ammonia synthesis reaction to occur, and a series of separators that recoup the liquid ammonia product at the right conditions for storage while recycling the gaseous hydrogen and nitrogen reactants.
While this plant design provides a layout to accomplish the task of producing ammonia in an environmentally friendly way, it is less friendly to the wallet of the plant owner. Selling the ammonia product at current market rates of 1.7 million dollars per year, which is another significant consideration why it takes such a large amount of time for the plant to become profitable.
It is our hope that ongoing refinement of solid oxide electrolytic units will enable their purchase at cheaper rates, and that as the environment worsens, a higher premium will be placed on chemical products that have been sourced renewably, both factors that could easily make this plant design a more viable option in the future than it currently is today
Creativity, ambiguous figures, and academic preference
Research suggests that ambiguous figure reversal is associated with creativity, but current evidence relies on subjective self-report that is difficult to quantify (Wiseman, Watt, Gilhooly, Georgiou, 2011 British Journal of Psychology 102 615-622). Using quantifiable measures of both phenomena we confirm this claim. We also find that participants studying science experience much more frequent reversal-a novel and intriguing finding. Keywords: ambiguous figure reversal, creativity, academic preferenc
Localization of Multi-Dimensional Wigner Distributions
A well known result of P. Flandrin states that a Gaussian uniquely maximizes
the integral of the Wigner distribution over every centered disc in the phase
plane. While there is no difficulty in generalizing this result to
higher-dimensional poly-discs, the generalization to balls is less obvious. In
this note we provide such a generalization.Comment: Minor corrections, to appear in the Journal of Mathematical Physic
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