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  • We apply the modern technique of approximation of multivariate functions - tensor train cross approximation - to the problem of the description of physical interactions between complex-shaped bodies in a context of computational nanomechanics. In this note we showcase one particular example - van der Waals interactions between two cylindrical bodies - relevant to modeling of carbon nanotube systems. The potential is viewed as a tensor (multidimensional table) which is represented in compact form with the help of tensor train decomposition. The described approach offers a universal solution for the description of van der Waals interactions between complex-shaped nanostructures and can be used within the framework of such systems of mesoscale modeling as recently emerged mesoscopic distinct element method (MDEM).

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  • We investigate which three dimensional near-horizon metrics $g_{NH}$ admit a compatible 1-form $X$ such that $(X, [g_{NH}])$ defines an Einstein-Weyl structure. We find explicit examples and see that some of the solutions give rise to Einstein-Weyl structures of dispersionless KP type and dispersionless Hirota (aka hyperCR) type.

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  • We prove three conjectures regarding the maximization of spectral invariants over certain families of graphs. Our most difficult result is that the join of $P_2$ and $P_{n-2}$ is the unique graph of maximum spectral radius over all planar graphs. This was conjectured by Boots and Royle in 1991 and independently by Cao and Vince in 1993. Similarly, we prove a conjecture of Cvetkovi\'c and Rowlinson from 1990 stating that the unique outerplanar graph of maximum spectral radius is the join of a vertex and $P_{n-1}$. Finally, we prove a conjecture of Aouchiche et al from 2008 stating that a pineapple graph is the unique connected graph maximizing the spectral radius minus the average degree. To prove our theorems, we use the leading eigenvector of a purported extremal graph to deduce structural properties about that graph. Using this setup, we give short proofs of several old results: Mantel's Theorem, Stanley's edge bound and extensions, the K\H{o}vari-S\'os-Tur\'an Theorem applied to $\m

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  • We study a function space $JN_p$ based on a condition introduced by John and Nirenberg as a variant of BMO. It is known that $L^p\subset JN_{p}\subsetneq L^{p,\infty}$, but otherwise the structure of $JN_p$ is largely a mystery. Our first main result is the construction of a function that belongs to $JN_p$ but not $L^p$, showing that the two spaces are not the same. Nevertheless, we prove that for monotone functions, the classes $JN_{p}$ and $L^p$ do coincide. Our second main result describes $JN_p$ as the dual of a new Hardy kind of space $HK_{p'}$.

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  • We propose a novel complex-analytic method for sums of i.i.d. random variables that are heavy-tailed and integer-valued. The method combines singularity analysis, Lindel\"of integrals, and bivariate saddle points. As an application, we prove three theorems on precise large and moderate deviations which provide a local variant of a result by S. V. Nagaev (1973). The theorems generalize five theorems by A. V. Nagaev (1968) on stretched exponential laws $p(k) = c\exp( -k^\alpha)$ and apply to logarithmic hazard functions $c\exp( - (\log k)^\beta)$, $\beta>2$; they cover the big jump domain as well as the small steps domain. The analytic proof is complemented by clear probabilistic heuristics. Critical sequences are determined with a non-convex variational problem.

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  • An important result in tilting theory states that a class of modules over a ring is a tilting class if and only if it is the Ext-orthogonal class to a set of compact modules of bounded projective dimension. Moreover, cotilting classes are precisely the resolving and definable subcategories of the module category whose Ext-orthogonal class has bounded injective dimension. In this article, we prove a derived counterpart of the statements above in the context of silting theory. Silting and cosilting complexes in the derived category of a ring generalise tilting and cotilting modules. They give rise to subcategories of the derived category, called silting and cosilting classes, which are part of both a t-structure and a co-t-structure. We characterise these subcategories: silting classes are precisely those which are intermediate and Ext-orthogonal classes to a set of compact objects, and cosilting classes are precisely the cosuspended, definable and co-intermediate subcategories of the de

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  • Joint transmission is a kind of cooperative transmission technology, which converts other cell interference into signal. In this letter, for single-user joint transmission, we propose that a power pool can be created in order to increase the system sum-rate or lower the power consumption. Then, we investigate the sum-rate maximization problem under this framework. Since it is impossible that subchannel gains for the two base stations are identical, we can obtain a much more concise structure and reduce variables to the half of original problem. And that the closed-form water-filling solution is unique and global optimum, because it is a convex optimization problem. Compared to the power allocation without pooling, the performance gain is verified by simulation.

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  • Let G be a simple simple-connected exceptional algebraic group of type G_2, F_4, E_6 or E_7 over an algebraically closed field k of characteristic p>0 with \g=Lie(G). For each nilpotent orbit G.e of \g, we list the Jordan blocks of the action of e on the minimal induced module V_min of \g. We also establish when the centralisers G_v of vectors v\in V_min and stabilisers \Stab_G<v> of 1-spaces <v>\subset V_min are smooth; that is, when \dim G_v=\dim\g_v or \dim \Stab_G<v>=\dim\Stab_\g<v>.

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  • We study the (virtual) indicability of the automorphism group $Aut(A_\Gamma)$ of the right-angled Artin group $A_\Gamma$ associated to a simplicial graph $\Gamma$. First, we identify two conditions -- denoted (B1) and (B2) -- on $\Gamma$ which together imply that $H^1(G, Z)=0$ for certain finite-index subgroups $G<Aut(A_\Gamma)$. On the other hand we will show that (B2) is equivalent to the matrix group ${\mathcal H} = {\rm Im}(Aut(A_\Gamma) \to Aut(H_1(A_\Gamma))) <GL(n,Z)$ not being virtually indicable, and also to $\mathcal H$ having Kazhdan's property (T). As a consequence, $Aut(A_\Gamma)$ virtually surjects onto $Z$ whenever $\Gamma$ does not satisfy (B2). In addition, we give an extra property of $\Gamma$ ensuring that $Aut(A_\Gamma)$ and $Out(A_\Gamma)$ virtually surject onto $Z$. Finally, in the appendix we offer some remarks on the linearity problem for $Aut(A_\Gamma)$.

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  • This paper deals with an inverse problem applied to the field of building physics to experimentally estimate three sorption isotherm coefficients of a wood fiber material. First, the mathematical model, based on convective transport of moisture, the optimal experiment design (OED) and the experimental set-up are presented. Then measurements of relative humidity within the material are carried out, after searching the OED, which is based on the computation of the sensitivity functions and a priori values of the unknown parameters employed in the mathematical model. The OED enables to plan the experimental conditions in terms of sensor positioning and boundary conditions out of 20 possible designs, ensuring the best accuracy for the identification method and, thus, for the estimated parameter. Two experimental procedures were identified: i) single step of relative humidity from 10% to 75% and ii) multiple steps of relative humidity 10-75-33-75% with an 8-day duration period for each step

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  • We give an asymptotic formula for the divisor sum $\sum_{c<n\leq N}\tau\left((n-b)(n-c)\right)$ for integers $b<c$ of the same parity. Interestingly, the coefficient of the main term does not depend on the discriminant as long as it is a full square. We also provide effective upper bounds of the average divisor sum for some of the reducible quadratic polynomials considered before, with the same main term as in the asymptotic formula.

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  • We study a functor from anti-Yetter Drinfeld modules to contramodules in the case of a Hopf algebra $H$. Some byproducts of this investigation are the establishment of sufficient conditions for this functor to be an equivalence, verification that the center of the opposite category of $H$-comodules is equivalent to anti-Yetter Drinfeld modules, and the observation of two types of periodicities of the generalized Yetter-Drinfeld modules introduced previously. Finally, we give an example of a symmetric $2$-contratrace on $H$-comodules that does not arise from an anti-Yetter Drinfeld module.

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  • We define a generalized Berezin transforms on line bundle over the complex hyperbolic space and we give it as a functions of the G-invariant laplacian on the line bundles.

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  • We show that for any fixed $\theta\in(-\frac{\pi}{2},\,0)\cup (0,\,\frac{\pi}{2})$, the 1-dimensional complex Ornstein-Uhlenbeck operator \begin{equation*} \tilde{\mathcal{L}}_{\theta}= 4\cos\theta \frac{\partial^2}{\partial z\partial \bar{z}}-e^{\mi\theta} z \frac{\partial}{\partial z}-e^{-\mi\theta}\bar{z} \frac{\partial}{\partial \bar{z}}, \end{equation*} is a normal (but nonsymmetric) diffusion operator.

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  • Let $E/\mathbf{Q}$ be a semistable elliptic curve of analytic rank one, and let $p>3$ be a prime for which the Galois group of the extension $\mathbf{Q}(E[p])/\mathbf{Q}$ is isomorphic to ${\rm GL}_2(\mathbf{F}_p)$. In this note, following a slight modification of the methods of Jetchev-Skinner-Wan, we use Iwasawa theory to establish the $p$-part of the Birch and Swinnerton-Dyer formula for $E$. In particular, we extend the main result of loc.cit. to primes of multiplicative reduction.

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  • Let $S=K[x_1,\ldots,x_n]$ be the polynomial ring over the field $K$, and let $I\subset S$ be a graded ideal. It is shown that for $k \gg0$ the postulation number of $I^k$ is bounded by a linear function of $k$, and it is a linear function of $k$, if $I$ is generated in a single degree. By using the relationship of the $h$-vector with the higher iterated Hilbert coefficients of $I^k$ it is shown that the Hilbert coefficients $e_i(I^k)$ of $I^k$ are polynomials for $k \gg 0$, whenever $I$ is generated in a single degree.

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  • In the paper, a mean-square minimization problem under terminal wealth constraint with partial observations is studied. The problem is naturally connected to the mean-variance hedging problem under incomplete information. A new approach to solving this problem is proposed. The paper provides a solution when the underlying pricing process is a square-integrable semimartingale. The proposed method for the study is based on the martingale representation. In special cases, the Clark-Ocone representation can be used to obtain explicit solutions. The results and the method are illustrated and supported by example with two correlated geometric Brownian motions.

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  • We characterize all varieties with a torus action of complexity one that admit iteration of Cox rings.

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  • Universal hashing, discovered by Carter and Wegman in 1979, has many important applications in computer science. MMH$^*$, which was shown to be $\Delta$-universal by Halevi and Krawczyk in 1997, is a well-known universal hash function family. We introduce a variant of MMH$^*$, that we call GRDH, where we use an arbitrary integer $n>1$ instead of prime $p$ and let the keys $\mathbf{x}=\langle x_1, \ldots, x_k \rangle \in \mathbb{Z}_n^k$ satisfy the conditions $\gcd(x_i,n)=t_i$ ($1\leq i\leq k$), where $t_1,\ldots,t_k$ are given positive divisors of $n$. Then via connecting the universal hashing problem to the number of solutions of restricted linear congruences, we prove that the family GRDH is an $\varepsilon$-almost-$\Delta$-universal family of hash functions for some $\varepsilon<1$ if and only if $n$ is odd and $\gcd(x_i,n)=t_i=1$ $(1\leq i\leq k)$. Furthermore, if these conditions are satisfied then GRDH is $\frac{1}{p-1}$-almost-$\Delta$-universal, where $p$ is the smallest

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  • We classify elements of a cluster modular group into three types. We characterize them in terms of fixed point property of the action on the tropical compactifications associated with the corresponding cluster ensemble. The characterization gives an analogue of the Nielsen-Thurston classification theory on the mapping class group of a surface.

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  • We deal with Orlicz-Sobolev embeddings in open subsets of $\mathbb{R}^n$. A necessary and sufficient condition is established for the existence of an optimal, i.e. largest possible, Orlicz-Sobolev space continuously embedded into a given Orlicz space. Moreover, the optimal Orlicz-Sobolev space is exhibited whenever it exists. Parallel questions are addressed for Orlicz-Sobolev embeddings into Orlicz spaces with respect to a Frostman measure, and, in particular, for trace embeddings on the boundary.

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  • This paper is interested in the problem of optimal stopping in a mean field game context. The notion of mixed solution is introduced to solve the system of partial differential equations which models this kind of problem. This notion emphasizes the fact that Nash equilibria of the game are in mixed strategies. Existence and uniqueness of such solutions are proved under general assumptions for both stationary and evolutive problems.

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  • If the Hasse invariant of a $p$-divisible group is small enough, then one can construct a canonical subgroup inside its $p$-torsion. We remark that, assuming the existence of a subgroup of adequate height in the $p$-torsion whose dual has small degree, the expected properties of the canonical subgroup can be easily proven. A fundamental relation is the equality between the Hasse invariant and the degree of the dual of the canonical subgroup. When one considers a $p$-divisible group $G$ with an action of the ring of integers of a (possibly ramified) finite extension of $\mathbb{Q}_p$, then much more can be said. One can define partial Hasse invariants ; they are natural in the unramified case, and generalize a construction of Reduzzi and Xiao in the general case. One can also define partial degrees for finite flat subgroups of $G$. We prove some properties for these partial Hasse invariants and partial degrees, and compute the partial degrees of the canonical subgroup.

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  • This work introduces, for the first time, non-orthogonal multiple access (NOMA) into short-packet communications to achieve low latency in wireless networks. Specifically, we address the optimization of transmission rates and power allocation to maximize the effective throughput of the user with a higher channel gain while guaranteeing the other user achieving a certain level of effective throughput. To demonstrate the benefits of NOMA, we analyze the performance of orthogonal multiple access (OMA) as a benchmark. Our examination shows that NOMA can significantly outperform OMA by achieving a higher effective throughput with the same latency or incurring a lower latency to achieve the same effective throughput targets. Surprisingly, we find that the performance gap between NOMA and OMA becomes more prominent when the effective throughput targets at the two users become closer to each other. This demonstrates that NOMA can significantly reduce the latency in the context of short-packet

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  • The class of problems treated here are elliptic partial differential equations with a homogeneous boundary condition and a non-linear perturbation obtained by composition with a fixed smooth function. The existence of solutions is obtained from the Leray--Schauder theorem or under a Landesman--Lazer condition on the data. Existence is carried over to a wide range of $L_p$-Sobolev spaces, using a non-trivial procedure to obtain a general regularity result. In fact the results are obtained in the general scales of Besov and Triebel--Lizorkin spaces.

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  • We construct smooth solutions to Ricci flow starting from a class of singular metrics and give asymptotics for the forward evolution. The singular metrics heal with a set of points (of codimension at least three) coming out of the singular point. We conjecture that these metrics arise as final-time limits of Ricci flow encountering a Type-I singularity modeled on $\mathbb{R}^{p+1} \times S^q$. This gives a picture of Ricci flow through a singularity, in which a neighborhood of the manifold changes topology from $D^{p+1} \times S^{q}$ to $S^p \times D^{q+1}$ (through the cone over $S^p \times S^q$.) We work in the class of doubly-warped product metrics. We also briefly discuss some possible smooth and non-smooth forward evolutions from other singular initial data.

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  • [REVISED VERSION] The aim of this paper is to state a sharp version of the K\"onig supremum theorem, an equivalent reformulation of the Hahn--Banach theorem. We apply it to derive statements of the Lagrange multipliers, Karush-Kuhn-Tucker and Fritz John type, for nonlinear infinite programs. We also show that a weak concept of convexity coming from minimax theory, infsup-convexity, is the adequate one for this kind of results.

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  • In this paper, we propose a learning-based low-overhead channel estimation method for coordinated beamforming in ultra-dense networks. We first show through simulation that the channel state information (CSI) of geographically separated base stations (BSs) exhibits strong non-linear correlations in terms of mutual information. This finding enables us to adopt a novel learning-based approach to remotely infer the quality of different beamforming patterns at a dense-layer BS based on the CSI of an umbrella control-layer BS. The proposed scheme can reduce channel acquisition overhead by replacing pilot-aided channel estimation with the online inference from an artificial neural network, which is fitted offline. Moreover, we propose to exploit joint learning of multiple CBSs and involve more candidate beam patterns to obtain better performance. Simulation results based on stochastic ray-tracing channel models show that the proposed scheme can reach an accuracy of 99.74% in settings with 20

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  • We prove a mass-angular momentum-charge inequality for a broad class of maximal, asymptotically flat, bi-axisymmetric initial data within the context of five-dimensional minimal supergravity. We further show that the charged Myers-Perry black hole initial data are the unique minimizers. In addition, we establish a rigidity statement for the relevant BPS bound, and give a variational characterization of BMPV black holes.

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  • High-dimensional chaotic dynamical systems can exhibit strongly transient features. These are often associated with instabilities that have finite-time duration. Because of the finite-time character of these transient events, their detection through infinite-time methods, e.g. long term averages, Lyapunov exponents or information about the statistical steady-state, is not possible. Here we utilize a recently developed framework, the Optimally Time-Dependent (OTD) modes, to extract a time-dependent subspace that spans the modes associated with transient features associated with finite-time instabilities. As the main result, we prove that the OTD modes, under appropriate conditions, converge exponentially fast to the eigendirections of the Cauchy--Green tensor associated with the most intense finite-time instabilities. Based on this observation, we develop a reduced-order method for the computation of finite-time Lyapunov exponents (FTLE) and vectors. In high-dimensional systems, the com

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  • Rate-Splitting (RS) has recently been shown to provide significant performance benefits in various multi-user transmission scenarios. In parallel, the huge degrees-of-freedom provided by the appealing massive Multiple-Input Multiple-Output (MIMO) necessitate the employment of inexpensive hardware, being more prone to hardware imperfections, in order to be a cost-efficient technology. Hence, in this work, we focus on a realistic massive Multiple-Input Single-Output (MISO) Broadcast Channel (BC) hampered by the inevitable hardware impairments. We consider a general experimentally validated model of hardware impairments, accounting for the presence of \textit{multiplicative distortion} due to phase noise, \textit{additive distortion noise} and \textit{thermal noise amplification}. Under both scenarios with perfect and imperfect channel state information at the transmitter (CSIT), we analyze the potential robustness of RS to each separate hardware imperfection. We analytically assess the s

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  • If $\gcd(r,t)=1$, then a theorem of Alladi offers the M\"obius sum identity $$-\sum_{\substack{ n \geq 2 \\ p_{\rm{min}}(n) \equiv r \pmod{t}}} \mu(n)n^{-1}= \frac{1}{\varphi(t)}. $$ Here $p_{\rm{min}}(n)$ is the smallest prime divisor of $n$. The right-hand side represents the proportion of primes in a fixed arithmetic progression modulo $t$. Locus generalized this to Chebotarev densities for Galois extensions. Answering a question of Alladi, we obtain analogs of these results to arithmetic densities of subsets of positive integers using $q$-series and integer partitions. For suitable subsets $\S$ of the positive integers with density $d_{\S}$, we prove that \[- \lim_{q \to 1} \sum_{\substack{ \lambda \in \mathcal{P} \\ \rm{sm}(\lambda) \in \S}} \mu_{\mathcal{P}} (\lambda)q^{\vert \lambda \vert} = d_{\S},\] where the sum is taken over integer partitions $\lambda$, $\mu_{\mathcal{P}}(\lambda)$ is a partition-theoretic M\"obius function, $\vert \lambda \vert$ is the size of partition $\

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  • This letter studies the power allocation and scheduling problem in two-cell distributed interference subtraction system. Through the interference is cancelled at one receiver side and the analysis of objective function monotony, our key result is the decoupling of power allocation and scheduling without loss of optimality. Simulation exhibits the significant gains of our proposed algorithm over open-loop power allocation with non-cooperation proportional fair scheduling.

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  • We derive Price inequalities for harmonic forms on manifolds without conjugate points and with a negative Ricci upper bound. The techniques employed in the proof work particularly well for manifolds of non-positive sectional curvature, and in this case we prove a strengthened Price inequality. We employ these inequalities to study the asymptotic behavior of the Betti numbers of coverings of Riemannian manifolds without conjugate points. Finally, we give a vanishing result for $L^{2}$-Betti numbers of closed manifolds without conjugate points.

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  • In this paper, we provide two methods of constructing quantum codes from linear codes over finite chain rings. The first one is derived from the Calderbank-Shor-Steane (CSS) construction applied to self-dual codes over finite chain rings. The second construction is derived from the CSS construction applied to Gray images of the linear codes over finite chain ring $\mathbb{F}_{p^{2m}}+u\mathbb{F}_{p^{2m}}$. The good parameters of quantum codes from cyclic codes over finite chain rings are obtained.

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  • In this paper we explore coarse properties of cusp-decomposable manifolds first defined by Nguy\^{e}n Phan. We describe the large scale geometry of the universal cover of a cusp-decomposable manifold and of quasi-isometries between two such universal covers. This description will provide us the tools to prove quasi-isometric rigidity for fundamental groups of cusp-decomposable manifolds.

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  • We generalize the Caldero-Chapoton formula for cluster algebras of finite type to the skew-symmetrizable case. This is done by replacing representation categories of Dynkin quivers by categories of locally free modules over certain Iwanaga-Gorenstein algebras introduced in Part I. The proof relies on the realization of the positive part of the enveloping algebra of a simple Lie algebra of the same finite type as a convolution algebra of constructible functions on representation varieties of $H$, given in Part III. Along the way, we obtain a new result on the PBW basis of this convolution algebra.

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  • Carl Friedrich Gauss is often given credit for providing the first correct proof of the fundamental theorem of algebra in his 1799 doctoral dissertation. However, Gauss's proof contained a significant gap. In this paper, we give an elementary way of filling the gap in Gauss's proof.

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  •  

    Replacing Disqus with GitHub Comments

    04-22 Hacker News 50

    Replacing Disqus with GitHub Comments

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  • Objects designed to explore the universe are now challenges for spaceflight

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  • The world's oceans are littered with trillions of pieces of plastic -- bottles, bags, toys, fishing nets and more, mostly in tiny particles -- and now this seaborne junk is making its way into the Arctic. From a report: The plastic was discovered by an international team of researchers who circumnavigated the Arctic on a five-month journey aboard the research vessel Tara in 2013. They sampled the ocean water along the way, looking at plastic pollution. And though the plastic concentrations were overall low, they located a specific region located north of the Greenland and the Barents seas with unusually high concentrations. They published their results in the journal Science Advances this week. It seems that the plastic is riding up to the pole with the Thermohaline Circulation, a "conveyor" belt ocean current that transports water from the lower latitudes of the Atlantic Ocean toward the poles. "[A]nd the Greenland and the Barents Seas act as a dead-end for this poleward conveyor belt

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  •  

    The Loch Ness Monster of Mollusks

    04-22 THE NEW YORKER 41

    The Loch Ness Monster of Mollusks

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  • Teenage hackers are motivated by idealism and impressing their mates rather than money, according to a study by the National Crime Agency. From a report: The law enforcement organisation interviewed teenagers and children as young as 12 who had been arrested or cautioned for computer-based crimes. It found that those interviewed, who had an average age of 17, were unlikely to be involved in theft, fraud or harassment. Instead they saw hacking as a "moral crusade", said Paul Hoare, senior manager at the NCA's cybercrime unit, who led the research. Others were motivated by a desire to tackle technical problems and prove themselves to friends, the report found. Speaking to BBC Radio 4's Today programme, Hoare said: "They don't understand the implications on business, government websites and individuals."

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  • An important correction to some lowball estimates of climate sensitivity.

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  • Show HN: WrapAPI v2 – Build APIs, scrapers, bots on any website

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  • Resources on creating programming languages

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  • Show HN: Deep Learning for Program Synthesis

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  • When the Galaxy S8 and S8+ first launched, several users reported a red tint to the displays. But then a few days passed and more reports emerged about the issue being widespread, especially in South Korea where many owners are facing this issue. According to XDA Developers, Samsung is aware of the issue and will be issuing a software update to fix it. From the report: Some thought this was just the nature of OLED technology. Because it's organic, it is expected to have some sort of variance from one device to another. We've seen this time and time again on Samsung devices, and others which are using AMOLED panels that were sourced from Samsung. This is generally not a widespread issue though and most of the time the difference is rather small. For whatever reason though, this doesn't seem to be the case with the Galaxy S8 and the Galaxy S8+. This new OTA update to fix the red tint issue is said to be coming next week at the end of April, and Samsung assures their customers that there

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  • Roman Seleznev bankrupted businesses, did $170 million in damage.

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  • Nokia has spread its patents around widely, and they keep popping up in lawsuits.

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  • An anonymous reader writes: According to multiple reports on Twitter, the Fedora Infrastructure Status page, and the #fedora-admin Freenode IRC channel, Red Hat is suffering a massive network outage at their primary data center. Details are sketchy at this point, but it looks to be impacting the Red Hat Customer Portal; as well as all their repositories (including Fedora, EPEL, Copr); their public build system, Koji; and a whole host of other popular services. There is no ETA for restoration of services at this point.

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  • WSJ describes newly unsealed depositions of 22 former employees, board members.

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  •  

    The Loch Ness Monster of Mollusks

    04-22 THE NEW YORKER 30

    The last time people thought very seriously about shipworms—people other than shipworm scientists, that is—was likely in the late nineteenth and early twentieth centuries, when wooden ships still reigned. A shipworm is in fact not a worm but a clam that looks like a worm and eats wood. The hinged shell of the typical bivalve has been reduced, in the shipworm, to a tiny pair of scrapers at the front end, which the animal uses for burrowing, like the tunnel-boring machines grinding away under Manhattan’s Second Avenue to extend the new subway line.

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  • Suddenly, Trump Derangement Syndrome is a thing, or is trying to become one.

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  • Apple's autonomous development vehicle seems less developed than previously imagined

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    What Is Science Good For?

    04-22 THE NEW YORKER 22

    Tomorrow, April 22nd—Earth Day—scientists, people who love science, and citizens concerned that government policies are increasingly detached from empirical reality will march in Washington, D.C., and nearly five hundred other cities around the world. Like any large group of protesters, the science marchers have struggled to craft their mission statement. “The March for Science champions robustly funded and publicly communicated science as a pillar of human freedom and prosperity,” they write, on their Web site. “We unite as a diverse, nonpartisan group to call for science that upholds the common good and for political leaders and policy makers to enact evidence based policies in the public interest.”

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  • WebL – A Programming Language for the Web (1997) [pdf]

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  • Your weekly selection of awesome robot videos

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    Type Systems as Macros

    04-22 Hacker News 27

    Type Systems as Macros

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  • What Happens When You Send a Zero-Day to a Bank?

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  • Global standards drove fuel-saving “mild hybrid” technology, but weakened EPA rules could stall U.S. deployment

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  • Tomorrow's Cities: Singapore's plans for a smart nation

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  • An anonymous reader quotes a report from Ars Technica: On Friday, the Wall Street Journal reported that the company "allegedly misled company directors" regarding its lab tests and used a shell company to buy commercial lab gear. These are just a few of the new revelations made by the Journal, which also include fake demonstrations for potential investors. The new information came from unsealed depositions by 22 former Theranos employees or members of its board of directors. They were deposed by Partner Fund Management LP, a hedge fund currently suing Theranos in Delaware state court. Theranos is also facing multiple lawsuits in federal court in California and Arizona, among others. The Journal, which did not publish the new filings, quoted former Theranos director Admiral Gary Roughead (Ret.), as saying that he was not aware that the company was using "extensive commercial analyzers" until it was reported in the press. The Journal described the filings as "some of the first substantiv

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  • Theranos Secretly Bought Outside Lab Gear, Ran Fake Tests: Court Filings

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  • The glEnd of Zelda(): Automatic 3Dification of NES Games (2016)

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  • Gillian Anderson: “You ready for more of this @davidduchovny?

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  • The maker of the gene therapy Glybera says it doesn’t have enough customers.

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  • Next Saturday, April 29th, is President Trump’s hundredth day in office, a historical marker used by the press to assess a new President’s progress since the first term of Franklin Delano Roosevelt. F.D.R. was grappling with the Great Depression, and he had a pliant Congress that would have passed almost anything he proposed. Presidents since then have often struggled to meet the expectations of the hundred-day report card but generally can point to a list of major legislative accomplishments. Trump does not have such a list. At the same time, the Trump White House is facing a much more consequential deadline, one that will help define his first months in office and perhaps his first term: absent a spending deal with Democrats and Republicans in Congress, next Saturday the government will shut down.

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    The SQL layer in CockroachDB

    04-22 Hacker News 40

    The SQL layer in CockroachDB

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    The Real Trump Agenda: Helping Big Business

    04-22 THE NEW YORKER 33

    What with U.S. aircraft carriers sailing in the wrong direction, Attorney General Jeff Sessions describing Hawaii as “an island in the Pacific,” and Sarah Palin, Ted Nugent, and Kid Rock larking around in the Oval Office, it’s been a pretty typical week for the Trump Administration: jaw-dropping, mind-addling, hard to keep up with. With all the chaos and dysfunction at the top, the Administration’s many pro-corporate regulatory initiatives are being somewhat overlooked by both the media and the public at large. This is wrong: these are decisions and actions that will have harmful consequences, and Trump’s own supporters will be among those hurt.

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  • Why MIT Switched from Scheme to Python (2009)

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    Net Neutrality Alive and Well in Canada

    04-22 Hacker News 43

    Net Neutrality Alive and Well in Canada

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    Big Data Exposes Big Falsehoods

    04-22 MIT Technology 33

    Analysis by Semantic Visions reveals intriguing differences between Russian and Western commentary about the shooting down of an airliner in 2014.

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  • Automated snare drum made to the order of Aphex Twin (2014)

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  • dryriver writes: I am someone who likes to post improvement suggestions for different software tools I use on the internet. If I see a function in a software that doesn't work well for me or could work better for everyone else, I immediately post suggestions as to how that function could be improved and made to work better for everybody. A striking phenomenon I have come across in posting such suggestions is the sheer number of "why would you want that at all" or "nobody needs that" or "the software is fine as it is" type responses from software users. What is particularly puzzling is that its not the developers of the software rejecting the suggestions -- its users of the software that often react sourly to improvement suggestions that could, if implemented well, benefit a lot of people using the software in question. I have observed this happening online for years even for really good software feature/function improvement ideas that actually wound up being implemented. My question is

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  • Canada cracks down on zero-rating while FCC allows paid data cap exemptions.

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  • An anonymous reader quotes a report from The Verge: The iPhone maker has recruited a pair of top Google satellite executives for a new hardware team, according to people familiar with the matter. John Fenwick, who led Google's spacecraft operations, and Michael Trela, head of satellite engineering, left Alphabet Inc.'s Google for Apple in recent weeks, the people said. They report to Greg Duffy, co-founder of camera maker Dropcam, who joined Apple earlier this year, the people said. With the recruits, Apple is bringing into its ranks two experts in the demanding, expensive field of satellite design and operation. At the moment, these endeavors typically fall into two fields: satellites for collecting images and those for communications. In a regulatory filing last year, Boeing Co. detailed a plan to provide broadband access through more than 1,000 satellites in low-earth orbit. The aerospace company has talked with Apple about the technology company being an investor-partner in the pro

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  • Many were waiting for the day when new and strong Amiga(One) will appear. That happened now. Currently, the X5000 can be purchased with the dual-core processor. In the future, a more powerful machine will be available. Is it worth buying the current model or wait for a four-core version? A look at the new X5000. Note that the author is Polish (I think), and English isn't her or his first language.

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    AmigaOne X5000 – first impression

    04-22 Hacker News 44

    AmigaOne X5000 – first impression

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    Amazon Strategy Teardown

    04-22 Hacker News 45

    Amazon Strategy Teardown

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