A wearable electrochemical sensor for the real-time measurement of sweat sodium concentration

We report a new method for the real-time quantitative analysis of sodium in human sweat, consolidating sweat collection and analysis in a single, integrated, wearable platform. This temporal data opens up new possibilities in the study of human physiology, broadly applicable from assessing high performance athletes to monitoring Cystic Fibrosis (CF) sufferers. Our compact Sodium Sensor Belt (SSB) consists of a sodium selective Ion Selective Electrode (ISE) integrated into a platform that can be interfaced with the human body during exercise. No skin cleaning regime or sweat storage technology is required as the sweat is continually wicked from the skin to a sensing surface and from there to a storage area via a fabric pump. Our results suggest that after an initial equilibration period, a steady-state sodium plateau concentration was reached. Atomic Absorption Spectroscopy (AAS) was used as a reference method, and this has confirmed the accuracy of the new continuous monitoring approach. The steady-state concentrations observed were found to fall within ranges previously found in the literature, which further validates the approach. Daily calibration repeatability (n 1⁄4 4) was +/- 3.0% RSD and over a three month period reproducibility was +/- 12.1% RSD (n 1⁄4 56). As a further application, we attempted to monitor the sweat of Cystic Fibrosis (CF) sufferers using the same device. We observed high sodium concentrations symptomatic of CF ($60 mM Na+) for two CF patients, with no conclusive results for the remaining patients due to their limited exercising capability, and high viscosity/low volume of sweat produced

A no-broadcasting theorem for modal quantum theory

The quantum no-broadcasting theorem has an analogue in modal quantum theory (MQT), a toy model based on finite fields. The failure of broadcasting in MQT is related to the failure of distributivity of the lattice of subspaces of the state space

Securely Computing Piecewise Constant Codes

Piecewise constant codes form an expressive and well-understood class of codes. In this work, we show that many piecewise constant codes admit exact coverings by polynomial-cardinality collections of hyperplanes. We prove that any boolean function whose on-set has been covered in just this manner can be evaluated by two parties with malicious security. This represents an interesting connection between covering codes, affine-linear algebra over prime fields, and secure computation. We observe that many natural boolean functions\u27 on-sets admit expressions as piecewise constant codes (and hence can be computed securely). Our protocol supports secure computation on committed inputs; we describe applications in blockchains and credentials. We finally present an efficient implementation of our protocol

On the Security of KOS

We study the security of the random oblivious transfer extension protocol of Keller, Orsini, and Scholl (CRYPTO \u2715), whose security proof was recently invalidated by Roy (CRYPTO \u2722). We show that KOS is asymptotically secure. Our proof involves a subtle analysis of the protocol\u27s correlation check , and introduces several new techniques. We also study the protocol\u27s concrete security. We establish concrete security for security parameter values on the order of 5,000. We present evidence that a stronger result than ours—if possible—is likely to require radically new ideas

Smooth Surfaces in Smooth Fourfolds with Vanishing First Chern Class

Hartshorne conjectured and Ellingsrud and Peskine proved that the smooth rational surfaces in $\mathbb{P}^4$ belong to only finitely many families. We formulate and study a collection of analogous problems in which $\mathbb{P}^4$ is replaced by a smooth fourfold $X$ with vanishing first integral Chern class. We embed such $X$ into a smooth ambient variety and count families of smooth surfaces which arise in $X$ from the ambient variety. We obtain various finiteness results in such settings. The central technique is the introduction of a new numerical invariant for smooth surfaces in smooth fourfolds with vanishing first Chern class

Many-out-of-Many Proofs and Applications to Anonymous Zether

Anonymous Zether, proposed by Bünz, Agrawal, Zamani, and Boneh (FC\u2720), is a private payment design whose wallets demand little bandwidth and need not remain online; this unique property makes it a compelling choice for resource-constrained devices. In this work, we describe an efficient construction of Anonymous Zether. Our protocol features proofs which grow only logarithmically in the size of the anonymity sets used, improving upon the linear growth attained by prior efforts. It also features competitive transaction sizes in practice (on the order of 3 kilobytes). Our central tool is a new family of extensions to Groth and Kohlweiss\u27s one-out-of-many proofs (Eurocrypt 2015), which efficiently prove statements about many messages among a list of commitments. These extensions prove knowledge of a secret subset of a public list, and assert that the commitments in the subset satisfy certain properties (expressed as linear equations). Remarkably, our communication remains logarithmic; our computation increases only by a logarithmic multiplicative factor. This technique is likely to be of independent interest. We present an open-source, Ethereum-based implementation of our Anonymous Zether construction

Smooth Surfaces in Smooth Fourfolds with Vanishing First Chern Class

Hartshorne conjectured and Ellingsrud and Peskine proved that the smooth rational surfaces in $\mathbb{P}^4$ belong to only finitely many families. We formulate and study a collection of analogous problems in which $\mathbb{P}^4$ is replaced by a smooth fourfold $X$ with vanishing first integral Chern class. We embed such $X$ into a smooth ambient variety and count families of smooth surfaces which arise in $X$ from the ambient variety. We obtain various finiteness results in such settings. The central technique is the introduction of a new numerical invariant for smooth surfaces in smooth fourfolds with vanishing first Chern class