Scheduling with Outliers

In classical scheduling problems, we are given jobs and machines, and have to schedule all the jobs to minimize some objective function. What if each job has a specified profit, and we are no longer required to process all jobs -- we can schedule any subset of jobs whose total profit is at least a (hard) target profit requirement, while still approximately minimizing the objective function? We refer to this class of problems as scheduling with outliers. This model was initiated by Charikar and Khuller (SODA'06) on the minimum max-response time in broadcast scheduling. We consider three other well-studied scheduling objectives: the generalized assignment problem, average weighted completion time, and average flow time, and provide LP-based approximation algorithms for them. For the minimum average flow time problem on identical machines, we give a logarithmic approximation algorithm for the case of unit profits based on rounding an LP relaxation; we also show a matching integrality gap. For the average weighted completion time problem on unrelated machines, we give a constant factor approximation. The algorithm is based on randomized rounding of the time-indexed LP relaxation strengthened by the knapsack-cover inequalities. For the generalized assignment problem with outliers, we give a simple reduction to GAP without outliers to obtain an algorithm whose makespan is within 3 times the optimum makespan, and whose cost is at most (1 + \epsilon) times the optimal cost.Comment: 23 pages, 3 figure

Rogue-Instance Security for Batch Knowledge Proofs

We propose a new notion of knowledge soundness, denoted rogue-instance security, for interactive and non-interactive batch knowledge proofs. Our notion, inspired by the standard notion of rogue-key security for multi-signature schemes, considers a setting in which a malicious prover is provided with an honestly-generated instance $x_1$, and may then be able to maliciously generate related rogue instances $x_2,\ldots,x_k$ for convincing a verifier in a batch knowledge proof of corresponding witnesses $w_1,\ldots,w_k$ for all $k$ instances - without actually having knowledge of the witness $w_1$ corresponding to the honestly-generated instance. This setting provides a powerful security guarantee for batch versions of a wide variety of practically-relevant protocols, such as Schnorr\u27s protocol and similar ones. We present a highly-efficient generic construction of a batch proof-of-knowledge applicable to any algebraic Sigma protocols. The algebraic property refers to a homomorphic structure of the underlying group and includes Schnorr\u27s protocol and others. We provide an almost tight security analysis for our generic batch protocol, which significantly improves upon the previously known security bounds even for the specific case of batch Schnorr protocol. We extend our results beyond algebraic Sigma protocols. We analyze the rogue-instance security of a general batch protocol with plus-one special soundness (a generalization of standard special soundness) and achieve improved security bounds in the generic case. Our results use a particular type of high-moment assumptions introduced by Rotem and Segev (CRYPTO 2021). These assumptions consider the hardness of a relation against algorithms with bounded expected running time. Although Rotem and Segev introduced these assumptions, they did not provide evidence to support their hardness. To substantiate and validate the high-moment assumptions, we present a new framework for assessing the concrete hardness of cryptographic problems against oracle algorithms with bounded expected runtime. Our framework covers generic models, including the generic group model, random oracle model, and more. Utilizing our framework, we achieve the first hardness result for these high-moment assumptions. In particular, we establish the second-moment hardness of the discrete-logarithm problem against expected-time algorithms in the generic group model

Hierarchical Functional Encryption

Functional encryption provides fine-grained access control for encrypted data, allowing each user to learn only specific functions of the encrypted data. We study the notion of hierarchical functional encryption, which augments functional encryption with delegation capabilities, offering significantly more expressive access control. We present a generic transformation that converts any general-purpose public-key functional encryption scheme into a hierarchical one without relying on any additional assumptions. This significantly refines our understanding of the power of functional encryption, showing that the existence of functional encryption is equivalent to that of its hierarchical generalization. Instantiating our transformation with the existing functional encryption schemes yields a variety of hierarchical schemes offering various trade-offs between their delegation capabilities (i.e., the depth and width of their hierarchical structures) and underlying assumptions. When starting with a scheme secure against an unbounded number of collusions, we can support arbitrary hierarchical structures. In addition, even when starting with schemes that are secure against a bounded number of collusions (which are known to exist under rather minimal assumptions such as the existence of public-key encryption and shallow pseudorandom generators), we can support hierarchical structures of bounded depth and width

Subthreshold Voltage Noise Due to Channel Fluctuations in Active Neuronal Membranes

Voltage-gated ion channels in neuronal membranes fluctuate randomly between different conformational states due to thermal agitation. Fluctuations between conducting and nonconducting states give rise to noisy membrane currents and subthreshold voltage fluctuations and may contribute to variability in spike timing. Here we study subthreshold voltage fluctuations due to active voltage-gated Na+ and K+ channels as predicted by two commonly used kinetic schemes: the Mainen et al. (1995) (MJHS) kinetic scheme, which has been used to model dendritic channels in cortical neurons, and the classical Hodgkin-Huxley (1952) (HH) kinetic scheme for the squid giant axon. We compute the magnitudes, amplitude distributions, and power spectral densities of the voltage noise in isopotential membrane patches predicted by these kinetic schemes. For both schemes, noise magnitudes increase rapidly with depolarization from rest. Noise is larger for smaller patch areas but is smaller for increased model temperatures. We contrast the results from Monte Carlo simulations of the stochastic nonlinear kinetic schemes with analytical, closed-form expressions derived using passive and quasi-active linear approximations to the kinetic schemes. For all subthreshold voltage ranges, the quasi-active linearized approximation is accurate within 8% and may thus be used in large-scale simulations of realistic neuronal geometries

Time-refraction and time-reflection above critical angle for total internal reflection

We study the time-reflection and time-refraction of waves caused by a spatial interface with a medium undergoing a sudden temporal change in permittivity. We show that monochromatic waves are transformed into a pulse by the permittivity change, and that time-reflection is enhanced at the vicinity of the critical angle for total internal reflection. In this regime, we find that the evanescent field is transformed into a propagating pulse by the sudden change in permittivity. These effects display enhancement of the time-reflection and high sensitivity near the critical angle, paving the way to experiments on time-reflection and photonic time-crystals at optical frequencies

Multiple State Electrostatically Formed Nanowire Transistors

This is the author accepted manuscript. The final version is available from IEEE via the DOI in this record.Electrostatically Formed Nanowire (EFN) based transistors have been suggested in the past as gas sensing devices. These transistors are multiple gate transistors in which the source to drain conduction path is determined by the bias applied to the back gate, and two junction gates. If a specific bias is applied to the side gates, the conduction band electrons between them are confined to a well-defined area forming a narrow channel- the Electrostatically Formed Nanowire. Recent work has shown that by applying non-symmetric bias on the side gates, the lateral position of the EFN can be controlled. We propose a novel Multiple State EFN Transistor (MSET) that utilizes this degree of freedom for the implementation of complete multiplexer functionality in a single transistor like device. The multiplexer functionality allows a very simple implementation of binary and multiple valued logic functions

Transplant Surgery Pipeline: A Report from the American Society of Transplant Surgeons Pipeline Taskforce

BACKGROUND: Transplant surgery fellowship has evolved over the years and today there are 66 accredited training programs in the US and Canada. There is growing concern, however, about the number of US-trained general surgery residents pursuing transplant surgery. In this study, we examined the transplant surgery pipeline, comparing it with other surgical subspecialty fellowships, and characterized the resident transplantation experience. METHODS: Datasets were compiled and analyzed from surgical fellowship match data obtained from the National Resident Matching Program and ACGME reports and relative fellowship competitiveness was assessed. The surgical resident training experience in transplantation was evaluated. RESULTS: From 2006 to 2018, a total of 1,094 applicants have applied for 946 transplant surgery fellowship positions; 299 (27.3%) were US graduates. During this period, there was a 0.8% decrease per year in US-trained surgical residents matching into transplant surgery (p = 0.042). In addition, transplant surgery was one of the least competitive fellowships compared with other National Resident Matching Program surgical subspeciality fellowships, as measured by the number of US applicants per available fellowship position, average number of fellowship programs listed on each applicant\u27s rank list, and proportion of unfilled fellowship positions (each, p \u3c 0.05). Finally, from 2015 to 2017, there were 57 general surgery residency programs that produced 77 transplant surgery fellows, but nearly one-half of the fellows (n = 36 [46.8%]) came from 16 (28.1%) programs. CONCLUSIONS: Transplant surgery is one of the least competitive and sought after surgical fellowships for US-trained residents. These findings highlight the need for dedicated efforts to increase exposure, mentorship, and interest in transplantation to recruit strong US graduates