Exportin-mediated nucleocytoplasmic transport maintains Pch2 homeostasis during meiosis.

The meiotic recombination checkpoint reinforces the order of events during meiotic prophase I, ensuring the accurate distribution of chromosomes to the gametes. The AAA+ ATPase Pch2 remodels the Hop1 axial protein enabling adequate levels of Hop1-T318 phosphorylation to support the ensuing checkpoint response. While these events are localized at chromosome axes, the checkpoint activating function of Pch2 relies on its cytoplasmic population. In contrast, forced nuclear accumulation of Pch2 leads to checkpoint inactivation. Here, we reveal the mechanism by which Pch2 travels from the cell nucleus to the cytoplasm to maintain Pch2 cellular homeostasis. Leptomycin B treatment provokes the nuclear accumulation of Pch2, indicating that its nucleocytoplasmic transport is mediated by the Crm1 exportin recognizing proteins containing Nuclear Export Signals (NESs). Consistently, leptomycin B leads to checkpoint inactivation and impaired Hop1 axial localization. Pch2 nucleocytoplasmic traffic is independent of its association with Zip1 and Orc1. We also identify a functional NES in the non-catalytic N-terminal domain of Pch2 that is required for its nucleocytoplasmic trafficking and proper checkpoint activity. In sum, we unveil another layer of control of Pch2 function during meiosis involving nuclear export via the exportin pathway that is crucial to maintain the critical balance of Pch2 distribution among different cellular compartments.

Universal neonatal hearing screening and delayed hearing loss or late-developmental hearing loss.

OBJECTIVE: To determine the percentage of children with permanent bilateral postnatal hearing loss in order to study its incidence, related risk factors, diagnosis and treatment. METHODS: Retrospective study to collect data on children diagnosed with hearing loss outside the neonatal period in the Hearing Loss Unit of the Hospital Universitario Central de Asturias, from April 2014 to April 2021. RESULTS: 52 cases met the inclusion criteria. The detection rate of congenital hearing loss in the neonatal screening programme in the same study period was 1.5 children per thousand newborns per year, adding postnatal hearing loss results in a rate of infant bilateral hearing loss of 2.7 children per thousand (55.5% and 44.4% respectively). Thirty-five children presented risk factors for hearing loss, of which 23 were at retrocochlear risk. The mean age at referral was 91.9 (18-185) months. Hearing aid fitting was indicated in 44 cases (84.6%). Cochlear implantation was indicated in eight cases (15.4%). DISCUSSION: Although congenital hearing loss accounts for the majority of childhood deafness, postnatal hearing loss has a significant incidence. This may be mainly due to: (1) that hearing impairment may arise in the first years of life, (2) that mild hearing loss as well as hearing loss in severe frequencies are undetectable by neonatal screening in some cases, (3) that some children may have false negative results. CONCLUSION: postnatal hearing loss requires identification of risk factors and long-term follow-up of children with hearing loss, as it needs to be detected and treated early.

Torsión uterina causada por miomatosis: reporte de un caso / Uterine torsion caused by myomatosis: A case report

Resumen ANTECEDENTES: La torsión uterina es una rotación del útero sobre su eje mayor de más de 45°; por lo general sucede en torno del istmo uterino. Los leiomiomas son el factor predisponente más frecuente en úteros no grávidos. OBJETIVO: Reportar el caso de una paciente con torsión uterina cervical y miomatosis de grandes elementos. CASO CLÍNICO: Paciente de 42 años, nuligesta, con antecedente de miomatosis uterina de grandes elementos de 27 x 27 cm. Los síntomas se iniciaron con síndrome doloroso abdominal intenso, tipo cólico, localizado en el hipogastrio y la fosa iliaca. En la exploración física el abdomen se percibió doloroso a la palpación superficial y profunda, con una tumoración cercana a la cicatriz umbilical (25 cm), móvil y dolorosa. En la laparotomía exploradora se encontró líquido peritoneal hemorrágico y se observó una torsión uterina (una vuelta) cerca del cuello del útero, además de un mioma subseroso en la cara posterior, de 27 x 27 cm. El útero, los anexos y las salpinges se advirtieron con datos francos de daño vascular, con áreas de isquemia. Por lo anterior se decidieron la histerectomía total abdominal y la salpingooforectomia bilateral. El informe histopatológico reportó: útero con cambio isquémico extenso panmural, sin evidencia de neoplasia maligna. CONCLUSIONES: El dolor abdominal es el síntoma más común de la torsión uterina que puede variar de leve a agudo. El diagnóstico preoperatorio rápido y preciso de torsión uterina es decisivo y se justifica la intervención quirúrgica de urgencia.

Abstract BACKGROUND: Uterine torsion is a rare entity that is defined as a rotation of the uterus on its major axis of more than 45°, generally occurring at the level of the uterine isthmus. Leiomyomas are the most frequent predisposing factor in non-gravid uterus. OBJECTIVE: Report of a case of a gynecological patient with uterine torsion at the cervical level in a uterus with uterine myomatosis of large elements. CLINICAL CASE: A 42-year-old patient, nulliparous, with a history of uterine myomatosis with large elements of 27 x 27 cm. The symptoms began with intense abdominal pain syndrome, colic type, located in the hypogastrium and the iliac fossa. On physical examination, the abdomen was perceived as painful on superficial and deep palpation, with a mobile and painful tumor close to the umbilical scar (25 cm). In the exploratory laparotomy, hemorrhagic peritoneal fluid was found and a uterine torsion (one turn) was observed near the cervix, as well as a subserous myoma on the posterior face, measuring 27 x 27 cm. The uterus, the annexes and the salpinges were noted with frank data of vascular damage, with areas of ischemia. Therefore, total abdominal hysterectomy and bilateral salpingo-oophorectomy were decided. The histopathological report reported: uterus with extensive panmural ischemic change, without evidence of malignancy. CONCLUSIONS: In uterine torsion, abdominal pain is the most common symptom and can range from mild to severe abdominal symptoms. Therefore, a prompt and accurate preoperative diagnosis of uterine torsion is crucial and urgent surgical intervention is warranted.

Smartphone-Based Localization for Passengers Commuting in Traffic Hubs.

Passengers commute between different modes of transportation in traffic hubs, and passenger localization is a key component for the effective functioning of these spaces. The smartphone-based localization system presented in this work is based on the 3D step and heading approach, which is adapted depending on the position of the smartphone, i.e., held in the hand or in the front pocket of the trousers. We use the accelerometer, gyroscope and barometer embedded in the smartphone to detect the steps and the direction of movement of the passenger. To correct the accumulated error, we detect landmarks, particularly staircases and elevators. To test our localization algorithm, we have recorded real-world mobility data in a test station in Munich city center where we have ground truth points. We achieve a 3D position accuracy of 12 m for a smartphone held in the hand and 10 m when the phone is placed in the front pocket of the trousers.

[Diagnostic accuracy of the automatic quantification software in patients with suspected COVID-19 of the Instituto Nacional de Cardiology Ignacio Chávez]. / Precisión diagnóstica del software de cuantificación automática en pacientes con sospecha de COVID-19 del Instituto Nacional de Cardiología Ignacio Chávez.

Objetivos: Establecer la precisión diagnóstica por tomografía computarizada (TC) de la probabilidad de neumopatía por enfermedad por coronavirus 2019 (COVID-19), dada por el sistema de inteligencia artificial (IA) diseñado por Siemens, y el resultado de la evaluación cualitativa CO-RADS (COVID-19 Reporting and Data System) con el estándar de referencia reacción en cadena de la polimerasa transcriptasa inversa (RT-PCR), entregando así la experiencia de nuestra institución. Métodos: Se realizó un estudio observacional, comparativo y retrolectivo en 192 pacientes adultos con sospecha de infección por coronavirus 2 del síndrome respiratorio agudo grave (SARS-CoV-2) que contaban con prueba PCR. Se obtuvo la información de precisión diagnóstica luego de comparar el estándar de referencia (RT- PCR) con el CO-RADS realizado por los observadores y la probabilidad de COVID-19 que arrojaron las imágenes de TC mediante la IA. Resultados: La comparación de la probabilidad de COVID-19 obtenida por la IA vs. la RT-PCR para SARS-CoV- 2 generó un AUC ROC de 0.774 (IC: 0.69-0.81) con p = 0.0001. La probabilidad de COVID-19 tuvo una precisión aceptable, con un buen valor predictivo positivo del 87.80%, pero con un pobre valor predictivo negativo del 58.80%. La variable CO-RADS vs. PCR obtuvo una mayor precisión con valores de sensibilidad y especificidad del 91.80 y 88.7% respectivamente. Conclusión: La comparación entre los resultados obtenidos por la IA y por la variable CO-RADS mostró mayor efectividad en esta última, sin embargo se logró documentar el alto impacto que tiene el sistema de cuantificación automática en la evaluación de estos pacientes, ya que permite agilizar la valoración del radiólogo y funciona como complemento en casos de dudas diagnósticas.

Surviving Older Patients Show Preserved Cellular and Humoral Immunological Memory Several Months After SARS-CoV-2 Infection.

Understanding how older people respond to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is critical if we are to confront the coronavirus disease 2019 (COVID-19) pandemic and establish effective vaccination strategies. Immunosenescence reduces the ability to respond to neoantigens and may compromise the life of infected individuals. Here, we analyzed the immunological memory to SARS-CoV-2 in 102 recovered patients aged over 60 years several months after the infection had been resolved. Specific memory T lymphocytes against the virus were measured by interferon-γ (IFN-γ) and granzyme B release by ELISpot; memory B-lymphocyte responses were quantified by detection of anti-S IgG1 producer cells by ELISpot and anti-S and anti-N antibodies were determined by enzyme-linked immunosorbent assay (ELISA). Memory T lymphocytes were found in peripheral blood of most of the studied donors, more than 7 months after the infection in some of them. Fewer patients maintained memory B lymphocytes, but antibodies, mainly anti-S, were highly durable and positively correlated with T responses. More robust humoral responses were found in patients who had more severe symptoms and had been admitted to hospital. We concluded that specific immunity against SARS-CoV-2 is effectively preserved regardless of age, despite the great heterogeneity of their immune responses, and that memory T lymphocytes and anti-S IgG might be more durable than memory B cells and anti-N IgG.

Novel Multi-IMU Tight Coupling Pedestrian Localization Exploiting Biomechanical Motion Constraints.

In this article, we present a novel tight coupling inertial localization system which simultaneously processes the measurements of two inertial measurement units (IMUs) mounted on the leg, namely the upper thigh and the front part of the foot. Moreover, the proposed system exploits motion constraints of each leg link; that is, the thigh and the foot. To derive these constraints, we carry out a motion tracking experiment to collect both ground truth data and inertial measurements from IMUs mounted on the leg. The performance of the tight coupling system is assessed with a data set of approximately 10 h. The evaluation shows that the average 2D-position error of the proposed tight coupling system is at least 50% better than the average 2D-position error of two state-of-the-art systems, whereas the average height error of the tight coupling system is at least 75% better than the average height error of the two state-of-the-art systems. In this work, we improve the accuracy of the position estimation by introducing biomechanical constraints in an inertial localization system. This article allows to observe, for the first time, heading errors of an inertial localization system by using only inertial measurements and without the need for using maps or repeating totally or partially the walked trajectory.

Perception of medical students about courses based on peer-assisted learning in five Peruvian universities.

OBJECTIVES: Peer-assisted learning (PAL) is a supportive strategy in medical education. In Peru, this method has been implemented by few universities. However, there are no consistent studies evaluating their acceptability by medical students. The objective of this study was to evaluate the perception of medical students about PAL in five Peruvian universities. RESULTS: A total of 79 medical students were included in the study. The mean age was 20.1 ± 1.9 years, 54% were female, and 87% were in the first 4 years of study. Most of the students were satisfied with classes and peer teachers. Similarly, most of the students agreed with the interest in developing teaching skills. It was also observed that 97% of students approved to implement PAL in medical education programs.

[Evolution of hand hygiene adherence of health professionals of specialized care.] / Evolución de la adherencia a la higiene de manos en un hospital de la Comunidad de Madrid.

OBJECTIVE: Hand hygiene (HH) is essential for the prevention of health care-associated infections (HAIs). Compliance rates documented in Spain and internationally are low, although improvement is possible using some strategies and training. The aim of this study was to know the evolution of the adherence to the 5 moments for hand hygiene of the health professionals of the Hospital Universitario Fundación Alcorcón and to propose measures to implement it. METHODS: A direct observation study about the compliance of the 5 moments for HH in this hospital for seven years was carried out. Different professional groups received training, using the traditional method and simulation learning. The data was summarized using percentages and absolute frequencies. They were analyzed using SPSS version 21 for Windows. RESULTS: Adherence increased from 37% in 2011 to 57.8% in 2019. Compliance in the 5 moments was higher after patient contact than before it. Nurses were one of the groups with the highest compliance. CONCLUSIONS: Even though they have improved, compliance rates need to be maintained and to increase especially in moments as crucial as before an aseptic procedure. Training and the implementation of strategies are key.

OBJETIVO: La higiene de manos (HM) es fundamental para la prevención de las infecciones relacionadas con la atención sanitaria (IRAS). Los índices de cumplimiento documentados, tanto en España como internacionalmente, son bajos, aunque una mejoría es posible utilizando algunas estrategias y formación. El objetivo de este estudio fue conocer la evolución de la adherencia a los 5 momentos de higiene de manos de los profesionales sanitarios del Hospital Universitario Fundación Alcorcón, y plantear medidas para implementarla. METODOS: Se realizó un estudio de observación directa sobre el cumplimiento de los 5 momentos de HM en este hospital durante siete años. Diferentes colectivos profesionales recibieron formación, utilizando el método tradicional y aprendizaje mediante simulación. Se realizó un análisis descriptivo, con frecuencias absolutas y relativas. Se analizaron mediante SPSS versión 21 para Windows. RESULTADOS: La adherencia aumentó de un 37% en 2011 a un 57,8% en 2019. El cumplimiento en los 5 momentos fue más alto después del contacto con el paciente que antes de este. El personal de enfermería fue uno de grupos con mayor cumplimiento. CONCLUSIONES: Aunque han mejorado, se necesita mantener los niveles de cumplimiento, y aumentarlos sobre todo en momentos tan cruciales como antes de realizar una técnica aséptica. La formación y la implementación de estrategias son clave.

Automatic Calibration of the Step Length Model of a Pocket INS by Means of a Foot Inertial Sensor.

All non-foot-mounted inertial localization systems have a common challenge: the need for calibrating the parameters of the step length model. The calibration of the parameters of a step length model is key for an accurate estimation of the pedestrian's step length, and therefore, for the accuracy of the position estimation. In a previous work, we provided a proof of concept on how to calibrate step length models with a foot inertial navigation system (INS), i.e., an INS based on an inertial measurement unit (IMU) mounted on the upper front part of the foot. The reason is that the foot INS does not require calibration thanks to the implementation of the strapdown algorithm. The goal of this article is to automatically calibrate the parameters of a step length model of the pocket INS by means of the foot INS. The step length model of the pocket INS has two parameters: the slope and offset of a first-order linear regression that relates the amplitude of the thigh pitch with the user's step length. Firstly, we show that it is necessary to estimate the two parameters of the step length model. Secondly, we propose a method to automatically estimate these parameters by means of a foot INS. Finally, we propose a practical implementation of the proposed method in the pocket INS. We evaluate the pocket INS with the proposed calibration method and we compare the results to the state of the art implementations of the pocket INS. The results show that the proposed automatic calibration method outperforms the previous work, which proves the need for calibrating all the parameters of the step length model of the pocket INS. In this work, we conclude that it is possible to use a foot INS to automatically calibrate all parameters of the step length model of the pocket INS. Since the calibration of the step length model is always needed, our proposed automatic calibration method is a key enabler for using the pocket INS.

Changing Trends in the Epidemiology and Risk Factors of Pneumocystis Pneumonia in Spain.

Objective: The information about the epidemiology of Pneumocystis pneumonia (PcP) in Europe is scarce, and in Spain there are only data nationwide on patients with HIV infection. This study has been carried out with the aim of knowing in our country the current epidemiological spectrum and the risk factors of PcP. Methods: Observational, descriptive transversal study that included all patients admitted in Spain with diagnosis upon discharge of PcP registered in the National Health System's Hospital Discharge Records Database of Spain, between 2008 and 2012. Results: Four thousand five hundred and fifty four cases of PcP were reported, 1,204 (26.4%) in HIV-negative patients. During the study period, mean annual incidence (cases per million) was 19.4, remaining globally stable, increasing from 4.4 to 6.3 in HIV-negative patients and decreasing from 15.5 to 13.4 among HIV-infected patients. Risk factors were identified in 85.5% of HIV-negative cases, the most frequent being hematological neoplams (29%), chronic lung diseases (15.9%), and non-hematological cancers (14.9%). Mean mortality and hospitalization cost were high (25.5% and 12,000 euros, respectively). Conclusions: The results of this first nationwide study in Spain allow a change in the misconception that, after the AIDS epidemic, PcP is an infrequent disease, showing that today it is an emerging problem in patients without HIV infection. These findings underlines the need for increased efforts toward a better characterization of risk groups to improve prophylactic strategies and reduce the burden of disease.

Tamizaje de sífilis congénita en el binomio madre-hijo: validez de la sangre de cordón / Screening for congenital syphilis in mother-child binomial: validity of cord blood / Triagem da sífilis congênita no binomio mãe-filho: validade do sangue do cordão

La sangre de cordón es una alternativa no invasiva que ha sido empleada para el tamizaje de sífilis congénita. Los objetivos del trabajo fueron evaluar la validez del uso de sangre de cordón como muestra para tamizaje de casos presuntivos de sífilis congénita, determinar la prevalencia de sífilis materna, estudiar la tasa de casos presuntivos de sífilis congénita y establecer el porcentaje de madres no estudiadas para sífilis en el periparto. Se realizó un análisis retrospectivo y observacional entre junio de 2017 y mayo de 2018. Se relevaron datos de serología de sangre de cordón y sangre de la madre. Se utilizó Unheated Serum Reagin como prueba de tamizaje y FTA-Abs y/o quimioluminiscencia como confirmatorias. Se excluyeron los binomios madre-hijo sin estudio de sangre de cordón. Binomios madre-hijo estudiados: 2.487. Sensibilidad y especificidad: 82,29% IC 95% (73,17- 89,33) y 99,96% IC 95% (99,76-100,00), respectivamente. Prevalencia de sífilis materna: 4,04%. Tasa de caso presuntivo de sífilis congénita: 26/1.000 RNV. Madres sin registros de serología para sífilis en el periparto: 70 (2,86%). La sangre de cordón no sería una muestra válida para el tamizaje debido a la baja sensibilidad encontrada, aunque en muchos casos es la única oportunidad de evaluar el binomio madre-hijo.

Cord blood is a non-invasive alternative which has been used for screening of congenital syphilis. The aims of the present study were to evaluate the validity of the use of cord blood as a sample for the screening of a probable congenital syphilis case, to study the prevalence of maternal syphilis, to analyse the rate of probable congenital syphilis case and to determine the percentage of non-studied mothers for syphilis in the peripartum. A retrospective and observational analysis was conducted between June 2017 and May 2018. Cord blood and maternal blood serology results were taken from the Laboratory Information System. Unheated Serum Reagin was used as a screening test and FTA-Abs and/or quimioluminiscense as confirmatory studies. Infant-mother binomies without cord blood studies were excluded. Infant-mother binomies studied: 2487. Sensibility and specificity 82.29% [95% CI: 73.17 to 89.33] and 99.96% [95% CI: 99.76 to 100.00], respectively. MSP prevalence: 4.04%. Probable congenital syphilis case rate: 26/1000 NB. Non-studied mothers for syphilis in the peripartum: 70 (2.86%). Cord blood would not be a valid sample for screening due to the low sensibility found, although in many cases it is the only opportunity to evaluate the infant-mother binomies.

O sangue do cordão é uma alternativa não invasiva que tem sido usada para triagem da sífilis congênita. Os objetivos do trabalho foram avaliar a validade do uso do sangue do cordão como amostra para o rastreio de um caso presumível de sífilis congénita, determinar a prevalência da sífilis materna, estudar a taxa de caso presumível de sífilis congénita e estabelecer a percentagem de mães em que não se analisa a sífilis no periparto. Foi realizada entre junho de 2017 e maio de 2018 uma análise retrospectiva e observacional, onde foram colectados os dados do Sistema de Computação Laboratorial de sorologia sangue do cordão e sangue da mãe. Foi utilizado um Unheated Serum Reagin como teste de triagem e FTA-Abs e/ou quimiluminescência como confirmatórias. Os binomios mãe-filho foram excluídos sem o estudo do sangue do cordão. Binomios mãe-filho estudado: 2.487. Sensibilidade e especificidade: 82,29% IC 95% (73,17-89,33) y 99,96% IC 95% (99,76-100,00), respectivamente. Prevalência de SFM: 4,04%. Taxa CPSC: 26/1.000 RNV. Mães sem registros sorológicos para sífilis no periparto: 70 (2,86%). O sangue do cordão não seria uma amostra válida para triagem devido à baixa sensibilidade encontrada, no entanto em muitos casos é a única oportunidade do avaliar o binomios mãe-filho.

Development of essential oil-based phyto-formulations to control the cattle tick Rhipicephalus microplus using a mixture design approach.

The cattle tick Rhipicephalus (Boophilus) microplus is one of the most important ectoparasites for livestock in tropical and subtropical areas around the world. This tick economically impacts cattle production by reducing weight gain and milk production. Moreover, it is a vector of pathogens causing diseases such as babesiosis and anaplasmosis. Conventional tick control relies mainly on the use of chemical acaricides; however, their intensive use has led to the rapid appearance of resistant tick populations. It is therefore necessary to look for alternative tick control products. In that sense, plant extracts might represent a promising source of new acaricides. Previously, we reported a significant acaricide effect of essential oils from selected plant species. In the present study, we used a mixture design approach to develop phyto-formulations by combining individual essential oils. We produced several mixtures at 10% containing different proportions of individual essential oils (ranging from 0 to 1) from cinnamon (Cinnamomum zeylanicum), cumin (Cuminum cyminum) and allspice (Pimenta dioica) and tested their acaricidal activity against R. microplus ticks by means of larval packet test (LPT) and adult immersion test (AIT) assays. The optimal mixture predicted against R. microplus was composed of 66%, 17% and 17% of essential oils from C. zeylanicum, C. cyminum and P. dioica, respectively. We generated an estimated response surface contour plot that estimates 80%-100% acaricidal efficacy. In the optimal mixture 34 compounds were identified, which represent 98.65% of the total composition, with cinnamaldehyde (37.77%), ß-caryophyllene (13.92%), methyl eugenol (12.27%) and cuminaldehyde (8.99%) being the major components. Next, we developed emulsions by combining the optimal mixture with several surfactants and determined particle size, Zeta potential, stability and bioactivity. Emulsions containing 2% and 5% Tween 20 or Tween 80 remain stable after 14 days at 54 °C. Finally, optimized emulsion retained a high acaricidal activity against larval and adult R. microplus ticks. Taken together, our findings showed the usefulness of mixture design method for the development of essential oil mixtures with potent acaricidal activity. These formulations have the potential to successfully control tick infestations.

Height Error Correction for Shoe-Mounted Inertial Sensors Exploiting Foot Dynamics.

Shoe-mounted inertial sensors are widespread deployed in satellite-denied scenarios because of the possibility to re-calibrate stepwise the estimated position. These re-calibrations, known as zero-velocity corrections, prevent an accumulated positioning error growth over time caused by the noise of current medium- and low-cost sensors. However, the error accumulated over time in the height estimation is still an issue under study. The objective of this article is to propose a height correction that is based on the dynamics of the foot. The presented algorithm analyzes the movement of the foot, which is different when walking on horizontal surfaces and stairs. The identification of horizontal surfaces and stairs is detailed in this article. For the assessment of the performance of the proposed height correction, a dataset of approximately 5 h recorded with 10 volunteers walking in a five-story building is employed. The error is evaluated using pre-defined ground truth points. We compare the height error estimated with and without applying the proposed correction and show that the height correction improves the vertical positioning accuracy up to 85.

Loose Coupling of Wearable-Based INSs with Automatic Heading Evaluation.

Position tracking of pedestrians by means of inertial sensors is a highly explored field of research. In fact, there are already many approaches to implement inertial navigation systems (INSs). However, most of them use a single inertial measurement unit (IMU) attached to the pedestrian's body. Since wearable-devices will be given items in the future, this work explores the implementation of an INS using two wearable-based IMUs. A loosely coupled approach is proposed to combine the outputs of wearable-based INSs. The latter are based on a pocket-mounted IMU and a foot-mounted IMU. The loosely coupled fusion combines the output of the two INSs not only when these outputs are least erroneous, but also automatically favoring the best output. This approach is named smart update. The main challenge is determining the quality of the heading estimation of each INS, which changes every time. In order to address this, a novel concept to determine the quality of the heading estimation is presented. This concept is subject to a patent application. The results show that the position error rate of the loosely coupled fusion is 10 cm/s better than either the foot INS's or pocket INS's error rate in 95% of the cases.

Dimers of formic acid: Structures, stability, and double proton transfer.

A stochastic search of the potential energy surface for the formic acid dimers results in 21 well-defined minima. A number of structures are reported here for the first time, others have already been experimentally detected or computationally predicted. Four types of different hydrogen bonds (HBs) are at play stabilizing the clusters: primary C=O⋯ H-O and H-O⋯ H-O and secondary C=O⋯ H-C and H-O⋯ H-C HBs corresponding to well-characterized bonding paths are identified. A novel C=O⋯ C stabilizing interaction is also reported. The double proton transfer reaction is calculated to occur in a synchronous fashion, with an energy barrier smaller than the energy needed to break up the dimers.

Landmark-Based Drift Compensation Algorithm for Inertial Pedestrian Navigation.

The navigation of pedestrians based on inertial sensors, i.e., accelerometers and gyroscopes, has experienced a great growth over the last years. However, the noise of medium- and low-cost sensors causes a high error in the orientation estimation, particularly in the yaw angle. This error, called drift, is due to the bias of the z-axis gyroscope and other slow changing errors, such as temperature variations. We propose a seamless landmark-based drift compensation algorithm that only uses inertial measurements. The proposed algorithm adds a great value to the state of the art, because the vast majority of the drift elimination algorithms apply corrections to the estimated position, but not to the yaw angle estimation. Instead, the presented algorithm computes the drift value and uses it to prevent yaw errors and therefore position errors. In order to achieve this goal, a detector of landmarks, i.e., corners and stairs, and an association algorithm have been developed. The results of the experiments show that it is possible to reliably detect corners and stairs using only inertial measurements eliminating the need that the user takes any action, e.g., pressing a button. Associations between re-visited landmarks are successfully made taking into account the uncertainty of the position. After that, the drift is computed out of all associations and used during a post-processing stage to obtain a low-drifted yaw angle estimation, that leads to successfully drift compensated trajectories. The proposed algorithm has been tested with quasi-error-free turn rate measurements introducing known biases and with medium-cost gyroscopes in 3D indoor and outdoor scenarios.

Use of the Magnetic Field for Improving Gyroscopes' Biases Estimation.

An accurate orientation is crucial to a satisfactory position in pedestrian navigation. The orientation estimation, however, is greatly affected by errors like the biases of gyroscopes. In order to minimize the error in the orientation, the biases of gyroscopes must be estimated and subtracted. In the state of the art it has been proposed, but not proved, that the estimation of the biases can be accomplished using magnetic field measurements. The objective of this work is to evaluate the effectiveness of using magnetic field measurements to estimate the biases of medium-cost micro-electromechanical sensors (MEMS) gyroscopes. We carry out the evaluation with experiments that cover both, quasi-error-free turn rate and magnetic measurements and medium-cost MEMS turn rate and magnetic measurements. The impact of different homogeneous magnetic field distributions and magnetically perturbed environments is analyzed. Additionally, the effect of the successful biases subtraction on the orientation and the estimated trajectory is detailed. Our results show that the use of magnetic field measurements is beneficial to the correct biases estimation. Further, we show that different magnetic field distributions affect differently the biases estimation process. Moreover, the biases are likewise correctly estimated under perturbed magnetic fields. However, for indoor and urban scenarios the biases estimation process is very slow.

Advanced Pedestrian Positioning System to Smartphones and Smartwatches.

In recent years, there has been an increasing interest in the development of pedestrian navigation systems for satellite-denied scenarios. The popularization of smartphones and smartwatches is an interesting opportunity for reducing the infrastructure cost of the positioning systems. Nowadays, smartphones include inertial sensors that can be used in pedestrian dead-reckoning (PDR) algorithms for the estimation of the user's position. Both smartphones and smartwatches include WiFi capabilities allowing the computation of the received signal strength (RSS). We develop a new method for the combination of RSS measurements from two different receivers using a Gaussian mixture model. We also analyze the implication of using a WiFi network designed for communication purposes in an indoor positioning system when the designer cannot control the network configuration. In this work, we design a hybrid positioning system that combines inertial measurements, from low-cost inertial sensors embedded in a smartphone, with RSS measurements through an extended Kalman filter. The system has been validated in a real scenario, and results show that our system improves the positioning accuracy of the PDR system thanks to the use of two WiFi receivers. The designed system obtains an accuracy up to 1.4 m in a scenario of 6000 m 2 .