Tetris is Hard, Even to Approximate

In the popular computer game of Tetris, the player is given a sequence of tetromino pieces and must pack them into a rectangular gameboard initially occupied by a given configuration of filled squares; any completely filled row of the gameboard is cleared and all pieces above it drop by one row. We prove that in the offline version of Tetris, it is NP-complete to maximize the number of cleared rows, maximize the number of tetrises (quadruples of rows simultaneously filled and cleared), minimize the maximum height of an occupied square, or maximize the number of pieces placed before the game ends. We furthermore show the extreme inapproximability of the first and last of these objectives to within a factor of p^(1-epsilon), when given a sequence of p pieces, and the inapproximability of the third objective to within a factor of (2 - epsilon), for any epsilon>0. Our results hold under several variations on the rules of Tetris, including different models of rotation, limitations on player agility, and restricted piece sets.Comment: 56 pages, 11 figure

Controlling TcT_c of Iridium films using interfacial proximity effects

High precision calorimetry using superconducting transition edge sensors requires the use of superconducting films with a suitable $T_c$, depending on the application. To advance high-precision macrocalorimetry, we require low-$T_c$ films that are easy to fabricate. A simple and effective way to suppress $T_c$ of superconducting Iridium through the proximity effect is demonstrated by using Ir/Pt bilayers as well as Au/Ir/Au trilayers. While Ir/Au films fabricated by applying heat to the substrate during Ir deposition have been used in the past for superconducting sensors, we present results of $T_c$ suppression on Iridium by deposition at room temperature in Au/Ir/Au trilayers and Ir/Pt bilayers in the range of $\sim$20-100~mK. Measurements of the relative impedance between the Ir/Pt bilayers and Au/Ir/Au trilayers fabricated show factor of $\sim$10 higher values in the Ir/Pt case. These new films could play a key role in the development of scalable superconducting transition edge sensors that require low-$T_c$ films to minimize heat capacity and maximize energy resolution, while keeping high-yield fabrication methods.Comment: 5 journal pages, 4 figure

Discovery potential for split supersymmetry with thermal dark matter

Supersymmetric extensions of the Standard Model with scalar superpartners above 10 TeV are well motivated since the Higgs boson mass can be explained by quantum corrections while maintaining gauge coupling unification. If supersymmetry breaking is transmitted to gauginos via anomaly mediation, the gaugino masses are loop suppressed compared to scalar masses, and the lightest supersymmetric particle is the Higgsino or wino, which can be the dark matter. In this setup, we identify the regions of parameter space that reproduce the observed Higgs boson mass and the thermal abundance of dark matter. We analyze the effects of complex phases in the gaugino mass parameters on the electron electric dipole moment (EDM) and the dark matter scattering cross section. We find that, for scalar masses up to 10 PeV and any size of the complex phases, the model with Higgsino dark matter is within reach of planned experiments -- Advanced ACME via electron EDM and LUX-ZEPLIN via dark matter direct detection -- with complementary discovery potentials, and the model with wino dark matter is within reach of future electron EDM experiments.Comment: 9 pages, 6 figure

Carbene footprinting accurately maps binding sites in protein–ligand and protein–protein interactions

Specific interactions between proteins and their binding partners are fundamental to life processes. The ability to detect protein complexes, and map their sites of binding, is crucial to understanding basic biology at the molecular level. Methods that employ sensitive analytical techniques such as mass spectrometry have the potential to provide valuable insights with very little material and on short time scales. Here we present a differential protein footprinting technique employing an efficient photo-activated probe for use with mass spectrometry. Using this methodology the location of a carbohydrate substrate was accurately mapped to the binding cleft of lysozyme, and in a more complex example, the interactions between a 100 kDa, multi-domain deubiquitinating enzyme, USP5 and a diubiquitin substrate were located to different functional domains. The much improved properties of this probe make carbene footprinting a viable method for rapid and accurate identification of protein binding sites utilizing benign, near-UV photoactivation

ProLoc: Robust Location Proofs in Hindsight

Many online services rely on self-reported locations of user devices likesmartphones. To mitigate harm from falsified self-reported locations, theliterature has proposed location proof services (LPSs), which provide proof ofa device's location by corroborating its self-reported location usingshort-range radio contacts with either trusted infrastructure or nearby devicesthat also report their locations. This paper presents ProLoc, a new LPS thatextends prior work in two ways. First, ProLoc relaxes prior work's proofs thata device was at a given location to proofs that a device was within distance"d" of a given location. We argue that these weaker proofs, which we call"region proofs", are important because (i) region proofs can be constructedwith few requirements on device reporting behavior as opposed to preciselocation proofs, and (ii) a quantitative bound on a device's distance from aknown epicenter is useful for many applications. For example, in the context ofcitizen reporting near an unexpected event (earthquake, violent protest, etc.),knowing the verified distances of the reporting devices from the event'sepicenter would be valuable for ranking the reports by relevance or flaggingfake reports. Second, ProLoc includes a novel mechanism to prevent collusionattacks where a set of attacker-controlled devices corroborate each others'false locations. Ours is the first mechanism that does not need additionalinfrastructure to handle attacks with made-up devices, which an attacker cancreate in any number at any location without any cost. For this, we rely on avariant of TrustRank applied to the self-reported trajectories and encountersof devices. Our goal is to prevent retroactive attacks where the adversarycannot predict ahead of time which fake location it will want to report, whichis the case for the reporting of unexpected events.<br

The ‘heritagisation’ of the British seaside resort: The rise of the ‘old penny’ arcade.

Amusement arcades have long been a key component of the British seaside resort. For almost a century, they enjoyed popularity and success and became established as a quintessential feature of the British seaside holiday. However, the advent of home-based video games along with recent gambling legislation has led to a decline of the seaside amusement arcade sector. Arcades gained a reputation as unsavoury places and their appearance and fortunes often mirrored those of the resorts in which they were located. However, over the past decade, a new variant of the seaside amusement arcade has appeared, featuring mechanical machines working on pre-decimal currency. Such ‘old penny arcades’ frequently describe themselves as museums or heritage centres and they offer an experience based on a nostalgic affection for the ‘traditional’ seaside holiday. They have appeared in the context of an increasing interest in the heritage of the British seaside resort and constitute one element of the ‘heritagisation’ of such resorts. This paper argues that such arcades can be important elements of strategies to reposition and rebrand resorts for the heritage tourism market

CoVault: A Secure Analytics Platform

In a secure analytics platform, data sources consent to the exclusive use oftheir data for a pre-defined set of analytics queries performed by a specificgroup of analysts, and for a limited period. If the platform is secure under asufficiently strong threat model, it can provide the missing link to enablingpowerful analytics of sensitive personal data, by alleviating data subjects'concerns about leakage and misuse of data. For instance, many types of powerfulanalytics that benefit public health, mobility, infrastructure, finance, orsustainable energy can be made differentially private, thus alleviatingconcerns about privacy. However, no platform currently exists that issufficiently secure to alleviate concerns about data leakage and misuse; as aresult, many types of analytics that would be in the interest of data subjectsand the public are not done. CoVault uses a new multi-party implementation offunctional encryption (FE) for secure analytics, which relies on a uniquecombination of secret sharing, multi-party secure computation (MPC), anddifferent trusted execution environments (TEEs). CoVault is secure under a verystrong threat model that tolerates compromise and side-channel attacks on anyone of a small set of parties and their TEEs. Despite the cost of MPC, we showthat CoVault scales to very large data sizes using map-reduce based queryparallelization. For example, we show that CoVault can perform queries relevantto epidemic analytics at scale.<br

Polyamorous Families – Parenting Practice, Stigma and Social Regulation

As a response to the greater visibility of alternative relationship and family forms, polyamory (i.e. the practice of consensual multi-partner relationships) has recently moved to the centre of public media attention. Questions of polyamory have emerged as a major concern within law, social policy, family sociology, gender and sexuality studies. Yet certain core issues have remained underexplored. This includes the distinctive nature of polyamorous intimacy, the structure of poly household formations and the dynamics of care work within poly families. In particular, poly parenting has been subject to tabooisation and scandalisation. Governing bodies, the judiciary and educational institutions have remained largely ignorant of polyamorous relationships. Research documents the exclusions of poly families (and individuals) from access to legal provisions and protections and their common discrimination in the courts, namely in custody cases. It further highlights the discrimination of polyidentified adolescents in school and college settings and the predicament that poly families face when interacting with public institutions (including schools and kindergardens). Insights into parenting practices and the organisation of childcare is vital for understanding the transformative potential of polyamorous ways of relating. It is also important for challenging the common demonisation and stigmatisation of polyamory within conservative family politics that perceives polyamory exclusively from a harm perspective. This paper will review and critically analyse existing research on poly parenting focussing on three dimensions: (a) parenting practices, (b) social and legal discrimination, and (c) parental response to stigmatisation. The paper argues for a stronger incorporation of queer perspectives within the guiding frameworks of research into parenting in consensually non-monogamous and polyamorous relationships to highlight the transformative potential of the ‘queer bonds’ that sustain many of these practices

Controlling TcT_c of Iridium Films Using the Proximity Effect

A superconducting Transition-Edge Sensor (TES) with low-$T_c$ is essential in a high resolution calorimetric detection. With a motivation of developing sensitive calorimeters for applications in cryogenic neutrinoless double beta decay searches, we have been investigating methods to reduce the $T_c$ of an Ir film down to 20 mK. Utilizing the proximity effect between a superconductor and a normal metal, we found two room temperature fabrication recipes of making Ir-based low-$T_c$ films. In the first approach, an Ir film sandwiched between two Au films, a Au/Ir/Au trilayer, has a tunable $T_c$ in the range of 20-100 mK depending on the relative thicknesses. In the second approach, a paramagnetic Pt thin film is used to create Ir/Pt bilayer with a tunable $T_c$ in the same range. We present detailed study of fabrication and characterization of Ir-based low-$T_c$ films, and compare the experimental results to theoretical models. We show that Ir-based films with predictable and reproducible critical temperature can be consistently fabricated for use in large scale detector applications.Comment: 5 figures, accepted in the Journal of Applied Physic