DEMONSTRATE THE ADVANTAGES OF USING ORDINAL ALPHA WHEN THE ASSUMPTIONS FOR CRONBACHS ALPHA ARE NOT MET; SHOW THE USEFULNESS OF ORDINAL ALPHA WITH THE CHILEAN VERSION OF THE WHO ALCOHOL USE DISORDERS IDENTIFICATION TEST (AUDIT); AND PROVIDE THE COMMANDS IN R PROGRAMMING LANGUAGE FOR PERFORMING THE RESPECTIVE CALCULATIONS.

IN THIS WORK WE DEVELOP A STUDY OF POSITIVE PERIODIC SOLUTIONS FOR A MATHEMATICAL MODEL OF THE DYNAMICS OF COMPUTER VIRUS PROPAGATION. WE PROPOSE A GENERALIZED COMPARTMENT MODEL OF SEIR-KS TYPE, SINCE WE CONSIDER THAT THE POPULATION IS PARTITIONED IN FIVE CLASSES: SUSCEPTIBLE (S); EXPOSED (E); INFECTED (I); RECOVERED (R); AND KILL SIGNALS (K), AND ASSUME THAT THE RATES OF VIRUS PROPAGATION ARE TIME DEPENDENT FUNCTIONS. THEN, WE INTRODUCE A SUFFICIENT CONDITION FOR THE EXISTENCE OF POSITIVE PERIODIC SOLUTIONS OF THE GENERALIZED SEIR-KS MODEL. THE PROOF OF THE MAIN RESULTS ARE BASED ON A PRIORI ESTIMATES OF THE SEIR-KS SYSTEM SOLUTIONS AND THE APPLICATION OF COINCIDENCE DEGREE THEORY. MOREOVER, WE PRESENT AN EXAMPLE OF A GENERALIZED SYSTEM SATISFYING THE SUFFICIENT CONDITION.

IN THIS PAPER, WE STUDY THE PROBLEM OF COEFFICIENTS IDENTIFICATION IN POPULATION GROWTH MODELS. WE CONSIDER THAT THE DYNAMICS OF THE POPULATION IS DESCRIBED BY A SYSTEM OF ORDINARY DIFFERENTIAL EQUATIONS OF SUSCEPTIBLE-INFECTIVE-RECOVERED (SIR) TYPE, AND WE ASSUME THAT WE HAVE A DISCRETE OBSERVATION OF INFECTIVE POPULATION. WE CONSTRUCT A CONTINUOUS OBSERVATION BY APPLYING TIME SERIES AND AN APPROPRIATE FITTING TO THE DISCRETE OBSERVATION DATA. THE IDENTIFICATION PROBLEM CONSISTS IN THE DETERMINATION OF DIFFERENT PARAMETERS IN THE GOVERNING EQUATIONS SUCH THAT THE INFECTIVE POPULATION OBTAINED AS SOLUTION OF THE SIR SYSTEM IS AS CLOSE AS TO THE OBSERVATION. WE INTRODUCE A REFORMULATION OF THE CALIBRATION PROBLEM AS AN OPTIMIZATION PROBLEM WHERE THE OBJECTIVE FUNCTION AND THE RESTRICTION ARE GIVEN BY THE COMPARISON IN THE L2-NORM OF THEORETICAL SOLUTION OF THE MATHEMATICAL MODEL AND THE OBSERVATION, AND THE SIR SYSTEM GOVERNING THE PHENOMENON, RESPECTIVELY. WE SOLVE NUMERICALLY THE OPTIMIZATION PROBLEM BY APPLYING THE GRADIENT METHOD WHERE THE GRADIENT OF THE COST FUNCTION IS OBTAINED BY INTRODUCING AN ADJOINT STATE. IN ADDITION, WE CONSIDER A NUMERICAL EXAMPLE TO ILLUSTRATE THE APPLICATION OF THE PROPOSED CALIBRATION METHOD.

WITH THE AIM OF MITIGATING THE DAMAGE CAUSED BY THE CORONAVIRUS DISEASE 2019 (COVID-19) PANDEMIC, IT IS IMPORTANT TO USE MODELS THAT ALLOW FORECASTING POSSIBLE NEW INFECTIONS ACCURATELY IN ORDER TO FACE THE PANDEMIC IN SPECIFIC SOCIOCULTURAL CONTEXTS IN THE BEST POSSIBLE WAY. OUR FIRST CONTRIBUTION IS EMPIRICAL. WE USE AN EXTENSIVE COVID-19 DATASET FROM NINE LATIN AMERICAN COUNTRIES FOR THE PERIOD OF 1 APRIL 2020 TO 31 DECEMBER 2021. OUR SECOND AND THIRD CONTRIBUTIONS ARE METHODOLOGICAL. WE EXTEND RELEVANT (I) STATE-SPACE MODELS WITH SCORE-DRIVEN DYNAMICS AND (II) NONLINEAR STATE-SPACE MODELS WITH UNOBSERVED COMPONENTS, RESPECTIVELY. WE USE WEEKLY SEASONAL EFFECTS, IN ADDITION TO THE LOCAL-LEVEL AND TREND FILTERS OF THE LITERATURE, FOR (I) AND (II), AND THE NEGATIVE BINOMIAL DISTRIBUTION FOR (II). WE FIND THAT THE STATISTICAL AND FORECASTING PERFORMANCES OF THE NOVEL SCORE-DRIVEN SPECIFICATIONS ARE SUPERIOR TO THOSE OF THE NONLINEAR STATE-SPACE MODELS WITH UNOBSERVED COMPONENTS MODEL, PROVIDING A POTENTIAL VALID ALTERNATIVE TO FORECASTING THE NUMBER OF POSSIBLE NEW COVID-19 INFECTIONS.

THIS PAPER IS ABOUT THE USE OF THE STATISTICAL PROCESS CONTROL (SPC) TO DETECT PROBLEMS GENERATED BY THE VARIABILITY INSIDE AUTOMATIC PROCESS CONTROL (APC). THIS PAPER TRIES TO FIND A SUCCESSFUL TOOL REGARDING TO DETECT VALUES OUT OF CONTROL IN AUTOMATIC SYSTEM. THIS KIND OF TOOL AFFORD EVALUATED THE CONTROL STRATEGY AND WILL BE USEFUL FOR THE DECISION MAKERS. STATISTICAL PROCESS CONTROL, MONITORING NO ONLY THE QUALITY VARIABLES BUT ALSO, VARIABLES IN THE AUTOMATIC PROCESSES THAT ARE CONTROLLING THE QUALITY. IN ORDER TO TEST THIS TOOL, IT WILL BE TESTED CHECKING THE STATUS OF MOISTURE CONTROL IN A MEDIUM DENSITY FIBERBOARD (MDF) LINE, THIS PROCESS, IS ONE OF THE MOST IMPORTANT IN THIS TYPE OF INDUSTRY. FURTHERMORE, THIS USEFUL STATISTICAL TOOL COULD BE USE TO EVALUATED THE PERFORMANCE OF ANY PROCESS INSIDE OF AN ORGANIZATION TO HELP IN THE IMPROVEMENT CYCLES.

THIS PAPER STUDIES THE GOODNESS OF FIT TEST FOR THE BIVARIATE HERMITE DISTRIBUTION. SPECIFICALLY, WE PROPOSE AND STUDY A CRAMER-VON MISES-TYPE TEST BASED ON THE EMPIRICAL PROBABILITY GENERATION FUNCTION. THE BOOTSTRAP CAN BE USED TO CONSISTENTLY ESTIMATE THE NULL DISTRIBUTION OF THE TEST STATISTICS. A SIMULATION STUDY INVESTIGATES THE GOODNESS OF THE BOOTSTRAP APPROACH FOR FINITE SAMPLE SIZES.

LOS DATOS DE CONTEO BIVARIADO SE PRESENTAN EN VARIAS DISCIPLINAS DIFERENTES Y LA DISTRIBUCIÓN DE POISSON BIVARIADA SE UTILIZA COMÚNMENTE PARA MODELARLOS. ESTE TRABAJO PROPONE Y ESTUDIA UNA PRUEBA DE BONDAD DE AJUSTE COMPUTACIONALMENTE CONVENIENTE PARA ESTA DISTRIBUCIÓN, QUE SE BASA EN UNA CONTRAPARTIDA EMPÍRICA DE UN SISTEMA DE ECUACIONES. LA PRUEBA ES CONSISTENTE CONTRA ALTERNATIVAS FIJAS. LA DISTRIBUCIÓN NULA DE LA PRUEBA PUEDE SER APROXIMADA CONSISTENTEMENTE POR UN BOOTSTRAP PARAMÉTRICO Y POR UN BOOTSTRAP PONDERADO. LA BONDAD DE ESTOS ESTIMADORES BOOTSTRAP Y LA POTENCIA PARA TAMAÑOS DE MUESTRA FINITOS SE ESTUDIAN NUMÉRICAMENTE. SE MUESTRA QUE LA PRUEBA PROPUESTA PUEDE EXTENDERSE NATURALMENTE A LA DISTRIBUCIÓN MULTIVARIANTE DE POISSON

THE BIVARIATE POISSON DISTRIBUTION IS COMMONLY USED TO MODEL BIVARIATE COUNT DATA. IN THIS PAPER WE STUDY A GOODNESS-OF-FIT TEST FOR THIS DISTRIBUTION. WE ALSO PROVIDE A REVIEW OF THE EXISTING TESTS FOR THE BIVARIATE POISSON DISTRIBUTION, AND ITS MULTIVARIATE EXTENSION (...)

SIMULATING THE PROBABILITY OF TYPE I ERROR IS A POWERFUL STATISTICAL TOOL THAT ALLOWS CONFIRMING IF THE STATISTICAL TEST ACHIEVES THE ESTABLISHED NOMINAL LEVEL. HOWEVER, ITS COMPUTATIONAL IMPLEMENTATION HAS THE DRAWBACK OF SIGNIFICANTLY LONG EXECUTION TIMES. THEREFORE, THIS ARTICLE ANALYZES THE PERFORMANCE OF TWO PARALLEL IMPLEMENTATIONS (PARRAPPLY AND BOOT) WHICH SIGNIFICANTLY REDUCE THE EXECUTION TIME OF SIMULATIONS OF TYPE I ERROR PROBABILITY FOR A GOODNESS-OF-FIT TEST FOR THE BIVARIATE POISSON DISTRIBUTION. THE RESULTS OBTAINED DEMONSTRATE HOW THE PARALLELIZATION STRATEGIES ACCELERATE THE SIMULATIONS, REDUCING THE TIME BY 50% TO 90% WHEN USING 2 TO 12 PROCESSORS RUNNING IN PARALLEL. THIS REDUCTION IS GRAPHICALLY EVIDENCED AS THE EXECUTION TIME OF THE ANALYZED PARALLEL VERSIONS FITS ALMOST PERFECTLY (?2?0.999 ) TO THE POWER MODEL ?=???, WHERE P IS THE NUMBER OF PROCESSORS USED, AND ?>0 AND ?

THIS PAPER MODELS THE POPULATION DYNAMICS AND COMPETITION OF TWO SYMPATRIC SPECIES OF LIZARDS LIOLAEMUS CYANOGASTER AND LIOLAEMUS TENUIS UNDER THE FOLLOWING SCENARIOS: (A) POPULATION DYNAMICS OF EACH SPECIES, (B) COMPETITION TO THERMOREGULATE, AND (C) COMPETITION FOR THE SUBSTRATE. THE HYPOTHESIS WAS THAT A VARIANT OF THE LOTKA?VOLTERRA MODEL IS ABLE TO EXPLAIN PATTERNS RELATED TO POPULATION DYNAMICS AND COMPETITION BETWEEN BOTH SPECIES. THE DATA USED COME FROM A STUDY CARRIED OUT BETWEEN SPRING AND AUTUMN OF 2011, 2012 AND 2013, IN THE CHILEAN LOCALITY OF NONGUÉN VALLEY. WITH THESE DATA WE ESTIMATE THE NUMBER OF INDIVIDUALS OF EACH SPECIES AS WELL AS THEIR BODY TEMPERATURE AND THE PLACE WHERE IT WAS FOUND (ON THE GROUND OR HIGHER). THE MODEL ANALYZED WAS APPROPRIATE FOR THE THREE SCENARIOS STUDIED AND IT DESCRIBED A PARSIMONIOUS COEXISTENCE BETWEEN THE SPECIES AND A POINT OF EQUILIBRIUM THAT TURNED OUT TO BE AN ASYMPTOTICALLY STABLE ATTRACTOR; THAT IS, IF THESE SPECIES START WITH A CERTAIN INITIAL AMOUNT, THEY WILL ALWAYS REACH AN EQUITABLE FINAL AMOUNT.

AN EXTENSION OF THE GENERALIZED AUTOREGRESSIVE SCORE (GAS) MODEL IS PRESENTED FOR TIME SERIES WITH EXCESS NULL OBSERVATIONS TO INCLUDE EXPLANATORY VARIABLES. AN EXTENSION OF THE GAS MODEL PROPOSED BY HARVEY AND ITO IS SUGGESTED, AND IT IS APPLIED TO PRECIPITATION DATA FROM A CITY IN CHILE. IT IS CONCLUDED THAT THE MODEL PROVIDES ADEQUATE PREDICTION, AND FURTHERMORE, AN ANALYSIS OF THE RELATIONSHIP BETWEEN THE PRECIPITATION VARIABLE AND THE EXPLANATORY VARIABLES IS SHOWN. THIS RELATIONSHIP IS COMPARED WITH THE METEOROLOGY LITERATURE, DEMONSTRATING CONCURRENCE.

GLOBAL CLIMATE CHANGE WILL HAVE A GREATER IMPACT ON ECTOTHERMS IN TROPICAL AND SUBTROPICAL COMMUNITIES THAN AT HIGHER LATITUDES, BECAUSE AMBIENT TEMPERATURES ARE CLOSER TO THE UPPER THERMAL LIMITS OF SPECIES. AMPHIBIAN SPECIES ARE HIGHLY DEPENDENT ON EXTERNAL WEATHER CONDITIONS, AND THE EFFECT OF GLOBAL WARMING ON THESE HAS BEEN EVALUATED RECENTLY. THE GREAT CHILEAN FROG (CALYPTOCEPHALELLA GAYI) IS AN ENDEMIC, MONOTYPIC SPECIES AND GENUS WHOSE CONSERVATION STATUS IS CONSIDERED VULNERABLE BECAUSE OF HIGH EXTRACTION PRESSURE FOR HUMAN CONSUMPTION, LACK OF REGULATORY MEASURES AND COMPREHENSION BY ITS CONSUMERS. THEIR POPULATIONS HAVE ALSO DECLINED DUE TO THE LOSS AND DESTRUCTION OF THEIR HABITATS. C. GAYI HAS NOT BEEN CONSIDERED AS AN OBJECT OF PHYSIOLOGICAL STUDY, SO THIS LARGE SPECIES IS NOT KNOWN AS ONE THAT CAN ADAPT TO CURRENT ENVIRONMENTAL CHANGES. IN THIS STUDY WE ANALYZE THE THERMOREGULATORY CAPACITY AND THERMAL EFFICIENCY OF C. GAYI TO DETERMINE ITS POTENTIAL FOR CLIMATIC ADAPTATION. THE RESULTS INDICATE THAT THIS SPECIES IS STRICTLY A THERMAL-CONFORMER; ITS THERMAL EFFICIENCY AND ITS ABILITY TO WITHSTAND HIGH TEMPERATURES ALLOW IT TO SUSTAIN ITSELF UNDER A CLIMATE CHANGE SCENARIO, HOWEVER, IT HAS THERMAL CONSTRAINTS THAT DO NOT ALLOW IT TO WITHSTAND TEMPERATURES GREATER THAN 30°C.

TIS PAPER DESIGNS AND IMPLEMENTS A METHODOLOGY TO MODEL THE EVOLUTION OF THE COVID-19 PANDEMIC, PRODUCED BY THE SARS COV-2 VIRUS, IN WHAT WAS CALLED THE FRST WAVE IN CHILE, WHICH LASTED FROM MARCH 2 TO 31 OCTOBER 2020. TE MODELS ARE BASED ON SIGMOIDAL GROWTH CURVES AND CAN BE USED TO PREDICT THE NUMBER OF DAILY INFECTIONS AND DEATHS IN FUTURE DAYS, MAKING THEM A USEFUL TOOL FOR SANITARY AUTHORITIES TO MANAGE AN EPIDEMIC. TE METHODOLOGY IS APPLIED TO THE ENTIRE COUNTRY AND TO EACH OF ITS MOST AFECTED REGIONS. IN ADDITION, THE DYNAMICS OF THESE MODELS ALLOW IT TO BE NURTURED WITH THE NEW INFORMATION THAT IS BEING PRODUCED AND FORECAST A TENTATIVE DATE ON WHICH THERE WOULD BE SOME CONTROL OVER THE PANDEMIC. MOREOVER, THESE MODELS ALLOW FOR PREDICTING THE TOTAL NUMBER OF INFECTED AND DECEASED PEOPLE AT THE TIME THE PANDEMIC IS UNDER CONTROL. HOWEVER, THE SIMPLICITY OF THESE MODELS, WHICH CONSIDER ONLY THE ACCUMULATED DATA OF THOSE INFECTED AND DECEASED, DOES NOT CONTEMPLATE AN INTERVENTION ANALYSIS SUCH AS VACCINATIONS, WHICH, AS IS KNOWN, ARE BEING EFECTIVE IN CONTROLLING THE PANDEMIC.

A TWO-DIMENSIONAL MATHEMATICAL MODEL, BASED ON THE FINITE-DIFFERENCE METHOD OF CALCULATING HEAT TRANSFER, HAS BEEN DEVELOPED TO SIMULATE THE TEMPERATURE IN A CYLINDRICAL STORAGE SILO CONTAINING MALTING BARLEY (...)

THE WORLD HEALTH ORGANIZATION HAS RECOMMENDED A RANGE OF SOCIAL AND HEALTH MEASURES TO MITIGATE THE SPREAD OF CORONAVIRUS DISEASE 2019 (COVID-19), INCLUDING STRATEGIES SUCH AS QUARANTINES, BORDER CLOSURES, SOCIAL DISTANCING, AND MASK USAGE, AMONG OTHERS. SPECIFICALLY, THE CHILEAN AUTHORITIES IMPLEMENTED THE ?STEP-BY-STEP? PLAN, BUILT ON THE CONCEPT OF DYNAMIC QUARANTINE. NUMEROUS STUDIES HAVE EXAMINED THE EFFECTIVENESS OF THESE QUARANTINES IN CHILE DURING THE PANDEMIC, UTILIZING DATA PUBLISHED BY THE CHILEAN MINISTRY OF HEALTH. THIS STUDY?S PRIMARY AIM WAS TO ENHANCE OUR UNDERSTANDING OF QUARANTINE EFFECTIVENESS IN CHILE DURING THE PANDEMIC. WE ACCOMPLISHED THIS BY ANALYZING THE DISTRIBUTIONAL BEHAVIOR OF THE TIME UNTIL THE COVID-19 PANDEMIC WAS DEEMED UNDER CONTROL OR NOT. IN OUR STUDY, WE DEFINED AN EVENT WITH TWO POTENTIAL OUTCOMES RELATED TO THE INSTANTANEOUS REPRODUCTIVE NUMBER (RT), WHICH SIGNIFIES THE TIME UNTIL A CHANGE IN THE EVENT OUTCOME OCCURS. IMPORTANTLY, WE DID NOT PREDEFINE A SPECIFIC TEMPORAL OBSERVATION UNIT.

THIS PAPER STUDIES GOODNESS-OF-FIT TESTS FOR THE BIVARIATE POISSON DISTRIBUTION. SPECIFICALLY, WE PROPOSE AND STUDY SEVERAL CRAMÉR?VON MISES TYPE TESTS BASED ON THE EMPIRICAL PROBABILITY GENERATING FUNCTION. THEY ARE CONSISTENT AGAINST FIXED ALTERNATIVES FOR ADEQUATE CHOICES OF THE WEIGHT FUNCTION INVOLVED IN THEIR DEFINITION. THEY ARE ALSO ABLE TO DETECT LOCAL ALTERNATIVES CONVERGING TO THE NULL AT A CERTAIN RATE. THE BOOTSTRAP CAN BE USED TO CONSISTENTLY ESTIMATE THE NULL DISTRIBUTION OF THE TEST STATISTICS. A SIMULATION STUDY INVESTIGATES THE GOODNESS OF THE BOOTSTRAP APPROXIMATION AND COMPARES THEIR POWERS FOR FINITE SAMPLE SIZES. EXTENSIONS FOR TESTING GOODNESS-OF-FIT FOR THE MULTIVARIATE POISSON DISTRIBUTION ARE ALSO DISCUSSED.