Integration of optogenetics with complementary methodologies in systems neuroscience

Modern optogenetics can be tuned to evoke activity that corresponds to naturally occurring local or global activity in timing, magnitude or individual-cell patterning. This outcome has been facilitated not only by the development of core features of optogenetics over the past 10 years (microbial-opsin variants, opsin-targeting strategies and light-targeting devices) but also by the recent integration of optogenetics with complementary technologies, spanning electrophysiology, activity imaging and anatomical methods for structural and molecular analysis. This integrated approach now supports optogenetic identification of the native, necessary and sufficient causal underpinnings of physiology and behaviour on acute or chronic timescales and across cellular, circuit-level or brain-wide spatial scales

On metric dimension of cube of trees

Let $G=(V,E)$ be a connected graph and $d_{G}(u,v)$ be the shortest distance between the vertices $u$ and $v$ in $G$. A set $S=\{s_{1},s_{2},\cdots,s_{n}\}\subset V(G)$ is said to be a {\em resolving set} if for all distinct vertices $u,v$ of $G$, there exist an element $s\in S$ such that $d(s,u)\neq d(s,v)$. The minimum cardinality of a resolving set for a graph $G$ is called the {\em metric dimension} of $G$ and it is denoted by $\beta{(G)}$. A resolving set having $\beta{(G)}$ number of vertices is named as {\em metric basis} of $G$. The metric dimension problem is to find a metric basis in a graph $G$, and it has several real-life applications in network theory, telecommunication, image processing, pattern recognition, and many other fields. In this article, we consider {\em cube of trees} $T^{3}=(V, E)$, where any two vertices $u,v$ are adjacent if and only if the distance between them is less than equal to three in $T$. We establish the necessary and sufficient conditions of a vertex subset of $V$ to become a resolving set for $T^{3}$. This helps determine the tight bounds (upper and lower) for the metric dimension of $T^{3}$. Then, for certain well-known cubes of trees, such as caterpillars, lobsters, spiders, and $d$-regular trees, we establish the boundaries of the metric dimension. Further, we characterize some restricted families of cube of trees satisfying $\beta{(T^{3})}=\beta{(T)}$. We provide a construction showing the existence of a cube of tree attaining every positive integer value as their metric dimension

Evolving Secret Sharing in Almost Semi-honest Model

Evolving secret sharing is a special kind of secret sharing where the number of shareholders is not known beforehand, i.e., at time t = 0. In classical secret sharing such a restriction was assumed inherently i.e., the the number of shareholders was given to the dealer’s algorithm as an input. Evolving secret sharing relaxes this condition. Pramanik and Adhikari left an open problem regarding malicious shareholders in the evolving setup, which we answer in this paper. We introduce a new cheating model, called the almost semi-honest model, where a shareholder who joins later can check the authenticity of share of previous ones. We use collision resistant hash function to construct such a secret sharing scheme with malicious node identification. Moreover, our scheme preserves the share size of Komargodski et al. (TCC 2016)

To Approach or Avoid: An Introductory Overview of the Study of Anxiety Using Rodent Assays

Anxiety is a widely studied phenomenon in behavioral neuroscience, but the recent literature lacks an overview of the major conceptual framework underlying anxiety research to introduce young researchers to the field. In this mini-review article, which is aimed toward new undergraduate and graduate students, we discuss how researchers exploit the approach-avoidance conflict, an internal conflict rodents face between exploration of novel environments and avoidance of danger, to inform rodent assays that allow for the measurement of anxiety-related behavior in the laboratory. We review five widely-used rodent anxiety assays, consider the pharmacological validity of these assays, and discuss neural circuits that have recently been shown to modulate anxiety using the assays described. Finally, we offer related lines of inquiry and comment on potential future directions

Efficient Construction of Visual Cryptographic Scheme for Compartmented Access Structures

In this paper, we consider a special type of secret sharing scheme known as Visual Cryptographic Scheme (VCS) in which the secret reconstruction is done visually without any mathematical computation unlike other secret sharing schemes. We put forward an efficient direct construction of a visual cryptographic scheme for compartmented access structure which generalizes the access structure for threshold as well as for threshold with certain essential participants. Up to the best of our knowledge, the scheme is the first proposed scheme for compartmented access structure in the literature of visual cryptography. Finding the closed form of relative contrast of a scheme is, in general, a combinatorially hard problem. We come up with a closed form of both pixel expansion as well as relative contrast. Numerical evidence shows that our scheme performs better in terms of both relative contrast as well as pixel expansion than the cumulative array based construction obtained as a particular case of general access structure

Multi-Bit Differential Fault Analysis of Grain-128 with Very Weak Assumptions

Very few differential fault attacks (DFA) were reported on {\em Grain-128} so far. In this paper we present a generic attack strategy that allows the adversary to challenge the cipher under different multi-bit fault models with faults at a targeted keystream generation round even if bit arrangement of the actual cipher device is unknown. Also unique identification of fault locations is not necessary. To the best of our knowledge, this paper assumes the weakest adversarial power ever considered in the open literature for DFA on {\em Grain-128} and develops the most realistic attack strategy so far on {\em Grain-128}. In particular, when a random area within $k \in \{1,2,3,4,5\}$ neighbourhood bits can only be disturbed by a single fault injection at the first keystream generation round ($k$-neighbourhood bit fault), without knowing the locations or the exact number of bits the injected fault has altered, our attack strategy always breaks the cipher with $5$ faults. In a weaker setup even if bit arrangement of the cipher device is unknown, bad-faults (at the first keystream generation round) are rejected with probabilities $0.999993$, $0.999979$, $0.999963$, $0.999946$ and $0.999921$ assuming that the adversary will use only 1, 2, 3, 4 and 5 neighbourhood bit faults respectively for {\em key-IV} recovery

Efficient Random Grid Visual Cryptographic Schemes having Essential Members

In this paper we consider ``OR based monochrome random grid visual cryptographic schemes (RGVCS) for $t$-$(k,n)^*$ access structure which is a generalization of the threshold $(k,n)$ access structure in the sense that in all the successful attempts to recover the secret image, the $t$ essential participants must always be present. Up to the best of our knowledge, the current proposed work is the first in the literature of RGVCS which provides efficient direct constructions for the $t$-$(k,n)^*$-RGVCS for ``OR based model. Finding the closed form of light contrast is a challenging work. However, in this paper we come up with the closed form of the light contrast for the ``OR based model. In literature, there are visual cryptographic schemes where the secret reconstruction is done by binary ``XOR operation instead of ``OR operation to increase the relative contrast of the decoded image. In this paper, we also propose an extended grid based $t$-$(k,n)^*$-RGVCS in which we replace the traditional ``OR operation by ``XOR operation. Note that the use of XOR operation indicates that the decoding must be performed computationally and not visually. We justified our schemes using both experimental as well as simulation based data

Probabilistic Signature Based Framework for Differential Fault Analysis of Stream Ciphers

Differential Fault Attack (DFA) has received serious attention in cryptographic literature and very recently such attacks have been mounted against several popular stream ciphers for example Grain v1, MICKEY 2.0 and Trivium, that are parts of the eStream hardware profile. The basic idea of the fault attacks consider injection of faults and the most general set-up should consider faults at random location and random time. Then one should identify the exact location and the exact timing of the fault (as well as multi bit faults) with the help of fault signatures. In this paper we consider this most general set-up and solve the problem of fault attack under a general framework, where probabilistic signatures are exploited. Our ideas subsume all the existing DFAs against the Grain family, MICKEY 2.0 and Trivium. In the process we provide improved fault attacks for all the versions of Grain family and also for MICKEY 2.0 (the attacks against Trivium are already quite optimal and thus there is not much scope to improve). Our generalized method can also take care of the cases where certain parts of the keystream bits are missing for authentication purpose. In particular, we show that the unsolved problem of identifying the faults in random time for Grain 128a can be solved in this manner. Our techniques can easily be applied to mount fault attack on any stream cipher of similar kind