On Quantum Advantage in Information Theoretic Single-Server PIR

In (single-server) Private Information Retrieval (PIR), a server holds a large database $DB$ of size $n$, and a client holds an index $i \in [n]$ and wishes to retrieve $DB[i]$ without revealing $i$ to the server. It is well known that information theoretic privacy even against an `honest but curious' server requires $\Omega(n)$ communication complexity. This is true even if quantum communication is allowed and is due to the ability of such an adversarial server to execute the protocol on a superposition of databases instead of on a specific database (`input purification attack'). Nevertheless, there have been some proposals of protocols that achieve sub-linear communication and appear to provide some notion of privacy. Most notably, a protocol due to Le Gall (ToC 2012) with communication complexity $O(\sqrt{n})$, and a protocol by Kerenidis et al. (QIC 2016) with communication complexity $O(\log(n))$, and $O(n)$ shared entanglement. We show that, in a sense, input purification is the only potent adversarial strategy, and protocols such as the two protocols above are secure in a restricted variant of the quantum honest but curious (a.k.a specious) model. More explicitly, we propose a restricted privacy notion called \emph{anchored privacy}, where the adversary is forced to execute on a classical database (i.e. the execution is anchored to a classical database). We show that for measurement-free protocols, anchored security against honest adversarial servers implies anchored privacy even against specious adversaries. Finally, we prove that even with (unlimited) pre-shared entanglement it is impossible to achieve security in the standard specious model with sub-linear communication, thus further substantiating the necessity of our relaxation. This lower bound may be of independent interest (in particular recalling that PIR is a special case of Fully Homomorphic Encryption)

The midbody ring scaffolds the abscission machinery in the absence of midbody microtubules.

Abscission completes cytokinesis to form the two daughter cells. Although abscission could be organized from the inside out by the microtubule-based midbody or from the outside in by the contractile ring-derived midbody ring, it is assumed that midbody microtubules scaffold the abscission machinery. In this paper, we assess the contribution of midbody microtubules versus the midbody ring in the Caenorhabditis elegans embryo. We show that abscission occurs in two stages. First, the cytoplasm in the daughter cells becomes isolated, coincident with formation of the intercellular bridge; proper progression through this stage required the septins (a midbody ring component) but not the membrane-remodeling endosomal sorting complex required for transport (ESCRT) machinery. Second, the midbody and midbody ring are released into a specific daughter cell during the subsequent cell division; this stage required the septins and the ESCRT machinery. Surprisingly, midbody microtubules were dispensable for both stages. These results delineate distinct steps during abscission and highlight the central role of the midbody ring, rather than midbody microtubules, in their execution

Genotypic Changes in Human Immunodeficiency Virus Type 1 Protease Associated with Reduced Susceptibility and Virologic Response to the Protease Inhibitor Tipranavir

Tipranavir is a novel, nonpeptidic protease inhibitor of human immunodeficiency virus type 1 (HIV-1) with activity against clinical HIV-1 isolates from treatment-experienced patients. HIV-1 genotypic and phenotypic data from phase II and III clinical trials of tipranavir with protease inhibitor-experienced patients were analyzed to determine the association of protease mutations with reduced susceptibility and virologic response to tipranavir. Specific protease mutations were identified based on stepwise multiple-regression analyses of phase II study data sets. Validation included analyses of phase III study data sets to determine if the same mutations would be selected and to assess how these mutations contribute to multiple-regression models of tipranavir-related phenotype and of virologic response. A tipranavir mutation score was developed from these analyses, which consisted of a unique string of 16 protease positions and 21 mutations (10V, 13V, 20M/R/V, 33F, 35G, 36I, 43T, 46L, 47V, 54A/M/V, 58E, 69K, 74P, 82L/T, 83D, and 84V). HIV-1 isolates displaying an increasing number of these tipranavir resistance-associated mutations had a reduced phenotypic susceptibility and virologic response to tipranavir. Regression models for predicting virologic response in phase III trials revealed that each point in the tipranavir score was associated with a 0.16-log(10) copies/ml-lower virologic response to tipranavir at week 24 of treatment. A lower number of points in the tipranavir score and a greater number of active drugs in the background regimen were predictive of virologic success. These analyses demonstrate that the tipranavir mutation score is a potentially valuable tool for predicting the virologic response to tipranavir in protease inhibitor-experienced patients

Eisenhower's disarmament dilemma: from chance for peace to open skies proposal

President Eisenhower's image as a promoter of ‘peace and nuclear disarmament’ was established through speeches he made such as ‘Atoms for Peace’ (December 1953) and ‘Open Skies’ proposal (July 1955). However, Eisenhower's approach to the subject cannot be grasped without an understanding of his attitude towards the relationship between arms, war and disarmament. As he saw it, not only would the mere existence of nuclear weapons not trigger a war, they were actually the best guarantee against the eruption of a global conflagration. The real threat to world security was the repressive, closed, totalitarian and expansionist Soviet regime. War could be prevented only by a dramatic change in the competing ‐ and threatening ‐ ideology and social structure embedded in the Soviet system. Until then, the existence of nuclear weapons would ensure the free world's safety