Tracks from hell - when finding a proof may be easier than checking it

We consider the popular smartphone game Trainyard: a puzzle game that requires the player to lay down tracks in order to route colored trains from departure stations to suitable arrival stations. While it is already known [Almanza et al., FUN 2016] that the problem of finding a solution to a given Trainyard instance (i.e., game level) is NP-hard, determining the computational complexity of checking whether a candidate solution (i.e., a track layout) solves the level was left as an open problem. In this paper we prove that this verification problem is PSPACE-complete, thus implying that Trainyard players might not only have a hard time finding solutions to a given level, but they might even be unable to efficiently recognize them

Extending Holding Time for Hot Foods

Humidifying the air inside a hot holding cabinet can greatly extend the holding time for hot foods by retarding the quality degradation of the food due to moisture loss. Not all cabinets are equally effective in maintaining temperature and humidity. A rudimentary understanding of how heat and moisture are transferred to the food will help operators select the cabinet that best meets operation’s needs. The authors address what works and why

Assessing the Utility of Restaurant Descriptors and Typologies for Advancing the Body of Knowledge in Restaurant Management

The study begins with a review of existing typologies in the restaurant management literature. Segment labels from three typologies are used as keywords to collect 251 empirical studies from nine relevant academic journals serving the restaurant management discipline. Content analysis of titles, abstracts, and methodology sections reveals inconsistent use of existing typologies and limited use of effective restaurant descriptors. Recommendations are offered to optimize the use of restaurant descriptors so that the content of empirical studies may be more effectively accessed, digested, and compared across, thereby enhancing the communication of advances in the restaurant management body of knowledge

Solid Waste Disposal: Independent Food Service Practices

Solid waste disposal is a major concern today. This study seeks to identify the current practices and attitudes of managers of independent food services toward solid waste management and the characteristics of food services which were most likely to be involved with a solid waste management progra

The Use of Thermal Capacity in Measuring the Effectiveness of Meals on Wheels Transport Containers

The Meals on Wheels (MOW) program is designed to help combat hunger in persons needing assistance. MOW has a duty not only to provide food but also to ensure that it reaches eligible clients safely. Given the population that MOW serves, transporting food safely takes on increased importance. This experiment focused on the major food safety issue of maintaining temperature integrity through the use of transport containers. For containers that did not contain electric heating elements, several factors influenced how fast the food temperature fell. Those factors included the U-value and size of the container as well as how many meals were in the container. As predicted, the smaller the U-value, the longer it took the temperature to fall. Larger containers did better at maintaining food temperatures, provided they were fully loaded. In general, fully loaded small and medium containers were better at maintaining food temperatures than larger containers loaded with the same number of meals

Search for long-lived particles decaying in the CMS end cap muon detectors in proton-proton collisions at √s = 13 TeV

Artículo escrito por un elevado número de autores, solo se referencian el que aparece en primer lugar, el nombre del grupo de colaboración, si le hubiere, y los autores pertenecientes a la UAMA search for long-lived particles (LLPs) produced in decays of standard model (SM) Higgs bosons is presented. The data sample consists of 137 fb−1 of proton-proton collisions at √s p = 13 TeV, recorded at the LHC in 2016–2018. A novel technique is employed to reconstruct decays of LLPs in the end cap muon detectors. The search is sensitive to a broad range of LLP decay modes and to masses as low as a few GeV. No excess of events above the SM background is observed. The most stringent limits to date on the branching fraction of the Higgs boson to LLPs subsequently decaying to quarks and ꞇ+ꞇ− are found for proper decay lengths greater than 6, 20, and 40 m, for LLP masses of 7, 15, and 40 GeV, respectivel

Measurement of the production cross section for Z + b jets in proton-proton collisions at √s = 13 TeV

Artículo escrito por un elevado número de autores, solo se referencian el que aparece en primer lugar, el nombre del grupo de colaboración, si le hubiere, y los autores pertenecientes a la UAMThe measurement of the cross section for the production of a Z boson, decaying to dielectrons or dimuons, in association with at least one bottom quark jet is performed with proton-proton collision data at The measurement of the cross section for the production of a Z boson, decaying to dielectrons or dimuons, in association with at least one bottom quark jet is performed with proton-proton collision data at √s=13 TeV. The data sample corresponds to an integrated luminosity of 137 fb-1, collected by the CMS experiment at the LHC during 2016-2018. The integrated cross sections for Z+≥1 b jet and Z+≥2 b jets are reported for the electron, muon, and combined channels. The fiducial cross sections in the combined channel are 6.52 ± 0.04(stat) ± 0.40(syst) ± 0.14(theo) pb for Z+ ≥ 1 b jet and 0.65±0.03(stat) ± 0.07(syst)± 0.02(theo) pb for Z+ ≥ 2 b jets. The differential cross section distributions are measured as functions of various kinematic observables that are useful for precision tests of perturbative quantum chromodynamics predictions. The ratios of integrated and differential cross sections for Z+≥2b jets and Z+≥1 b jet processes are also determined. The value of the integrated cross section ratio measured in the combined channel is 0.100 ± 0.005(stat) ± 0.007(syst) ± 0.003(theo). All measurements are compared with predictions from various event generators.s = 13 TeV. The data sample corresponds to an integrated luminosity of 137 fb-1, collected by the CMS experiment at the LHC during 2016-2018. The integrated cross sections for Z+≥1 b jet and Z+≥2 b jets are reported for the electron, muon, and combined channels. The fiducial cross sections in the combined channel are 6.52±0.04(stat)±0.40(syst)±0.14(theo) pb for Z+ ≥ 1 b jet and 0.65±0.03(stat) ± 0.07(syst) ± 0.02(theo) pb for Z+ ≥ 2 b jets. The differential cross section distributions are measured as functions of various kinematic observables that are useful for precision tests of perturbative quantum chromodynamics predictions. The ratios of integrated and differential cross sections for Z+ ≥ 2b jets and Z+ ≥ 1 b jet processes are also determined. The value of the integrated cross section ratio measured in the combined channel is 0.100 ± 0.005(stat) ± 0.007(syst) ± 0.003(theo). All measurements are compared with predictions from various event generator