Efecto de confinamiento espacial y de núcleo de tamaño finito en sistemas atómicos

Se estudia el comportamiento de distintos sistemas atómicos cuando son sometidos a altas presiones externas: átomos hidrogenoides, de helio y litio. La presión ejercida se modela mediante el confinamiento espacial de los átomos, dentro de un pozo de potencial con simetría esférica, tanto de paredes impenetrables como penetrables. Se estudian diversas propiedades de los sistemas cuánticos confinados. En el átomo de hidrógeno: la polarizabilidad, la presión, el desdoblamiento hiperfino, el apantallamiento magnético y la probabilidad de tunelamiento (en el caso de confinamiento dentro de paredes penetrables). En el átomo de helio: la polarizabilidad y los potenciales de ionización. En el átomo de litio: el efecto producido por el confinamiento sobre el estado base del sistema. Para hallar la energía del estado base de los sistemas descritos anteriormente, se hace uso del método variacional de Rayleigh-Ritz. Para el átomo hidrogenoide confinado, también se resuelve de forma exacta la ecuación de Schrödinger, escribiendo la solución en términos de funciones hipergeométricas confluentes, y se calculan soluciones numéricas con muy alta precisión. Además estudiamos algunas propiedades poco consideradas en la literatura. Por ejemplo, para el átomo de hidrógeno confinado: el espectro de estructura fina para el estado base y algunos estados excitados, y correcciones relativistas. Estudiamos el efecto de considerar un núcleo de volumen finito, en lugar de un núcleo de tamaño puntual (como habitualmente se utiliza), sobre la energía del estado base de sistemas atómicos confinados de uno, dos y tres electrones. También estudiamos átomos exóticos confinados: los llamados átomos muónicos. Se analiza el comportamiento de la entropía informática de Shannon en el espacio de coordenadas en los sistemas cuánticos confinados, y su posible aplicación como medida de la calidad de la función de onda, así como su uso como medida de la localización (o deslocalización) de las partículas dentro de un sistema confinado.We study the behavior of different atomic systems (hydrogen-like atoms, helium and lithium) when they are subjected to high external pressures. The exerted pressure is modeled by spatial confinement of the atoms, inside a spherical potential for both impenetrable and penetrable walls. We study different properties of the confined quantum systems. For a hydrogen atom, polarizability, pressure, hyperfine splitting, magnetic screening and the tunneling probability (for the case of confinement inside penetrable walls) are analyzed, whereas for helium, polarizability and ionization potentials. Also, confinement induced effects are studied for lithium ground state. In order to analyze such effects for the above described systems, we use the Rayleigh-Ritz variational method. For a confined hydrogen-like atom, we solve the Schrödinger equation in an exact manner by writing the solution in terms of confluent hypergeometric functions, and we calculate numerical solutions with a very high accuracy. We also study some properties seldom considered in the literature. For example, for the confined hydrogen atom, the fine structure spectrum for the ground and some excited states, in conjunction with relativistic corrections. In addition, we study effects arising from spatially extending the nuclear region through a finite volume occupied by the nucleus, instead of considering it a point size particle (as it is usually assumed), when analyzing the ground state energy of atomic systems of one, two and three electrons. We also study exotic confined atoms, the so called muonic atoms. We analyze the Shannon information entropy behavior in the coordinate space for quantum confined systems, viewed as an application for measuring the quality of the wave function, as well as its use as a measure of localization and delocalization of particles inside a confined system

Métodos de solución al problema del átomo de hidrógeno confinado

Se estudia el efecto de tamaño en el átomo de hidrógeno confinado dentro de una esfera impenetrable de radio . Este problema se resuelve mediante diversos métodos aproximados: método variacional lineal y no lineal, solución numérica de la ecuación de Schrödinger y teoría de perturbaciones independientes del tiempo. Para cada método usado se calculan las energías propias del átomo de hidrógeno confinado como funciones del radio de confinamiento, así como algunos valores esperados de la posición del electrón. Se comparan los resultados obtenidos con los datos reportados en la literatura y se analizan las ventajas y desventajas en la utilización de cada método. Se hacen algunas observaciones sobre el cálculo de la estructura fina del átomo de hidrógeno confinado

Impact of COVID-19 on cardiovascular testing in the United States versus the rest of the world

Objectives: This study sought to quantify and compare the decline in volumes of cardiovascular procedures between the United States and non-US institutions during the early phase of the coronavirus disease-2019 (COVID-19) pandemic. Background: The COVID-19 pandemic has disrupted the care of many non-COVID-19 illnesses. Reductions in diagnostic cardiovascular testing around the world have led to concerns over the implications of reduced testing for cardiovascular disease (CVD) morbidity and mortality. Methods: Data were submitted to the INCAPS-COVID (International Atomic Energy Agency Non-Invasive Cardiology Protocols Study of COVID-19), a multinational registry comprising 909 institutions in 108 countries (including 155 facilities in 40 U.S. states), assessing the impact of the COVID-19 pandemic on volumes of diagnostic cardiovascular procedures. Data were obtained for April 2020 and compared with volumes of baseline procedures from March 2019. We compared laboratory characteristics, practices, and procedure volumes between U.S. and non-U.S. facilities and between U.S. geographic regions and identified factors associated with volume reduction in the United States. Results: Reductions in the volumes of procedures in the United States were similar to those in non-U.S. facilities (68% vs. 63%, respectively; p = 0.237), although U.S. facilities reported greater reductions in invasive coronary angiography (69% vs. 53%, respectively; p < 0.001). Significantly more U.S. facilities reported increased use of telehealth and patient screening measures than non-U.S. facilities, such as temperature checks, symptom screenings, and COVID-19 testing. Reductions in volumes of procedures differed between U.S. regions, with larger declines observed in the Northeast (76%) and Midwest (74%) than in the South (62%) and West (44%). Prevalence of COVID-19, staff redeployments, outpatient centers, and urban centers were associated with greater reductions in volume in U.S. facilities in a multivariable analysis. Conclusions: We observed marked reductions in U.S. cardiovascular testing in the early phase of the pandemic and significant variability between U.S. regions. The association between reductions of volumes and COVID-19 prevalence in the United States highlighted the need for proactive efforts to maintain access to cardiovascular testing in areas most affected by outbreaks of COVID-19 infection

Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study

Summary Background Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally. Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income countries globally, and identified factors associated with mortality. Methods We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis, exomphalos, anorectal malformation, and Hirschsprung’s disease. Recruitment was of consecutive patients for a minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause, in-hospital mortality for all conditions combined and each condition individually, stratified by country income status. We did a complete case analysis. Findings We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal malformation, and 517 with Hirschsprung’s disease) from 264 hospitals (89 in high-income countries, 166 in middleincome countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male. Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3). Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups). Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in lowincome countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries; p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11], p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20 [1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention (ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed (ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65 [0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality. Interpretation Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between lowincome, middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger than 5 years by 2030

Craniocerebral gunshot injuries; A review of the current literature

Craniocerebral gunshot injuries (CGI) are increasingly encountered by neurosurgeons in civilian and urban settings. Unfortunately, more prevalent condition in developing countries, with major armed conflicts which is still persisting, since the main trigger is violence at the national or state level. Management goals of CGI should focus on aggressive resuscitation and correction of coagulopathy; those with stable vital signs should undergo CT scan head at the earliest possible opportunity. Neuroimaging is vital for planning of surgical management, especially to determine the type of surgery, routes of the approach to the surgical target area and extraction of the impacted foreign bodies, however, surgical management is not always indicated. Although subset of such cases may be managed even with non-surgical management. The treatment comprises of immediate life salvaging resuscitative measures including control of the persistent bleeding, care of associated injury, management of raised intracranial pressure, prevention of cerebrospinal fistula formation by primary watertight dural repair and prevention of infection, through extensive debridement of contaminated, macerated or ischemic tissues; preservation of nervous tissue and restoration of anatomic structures through the hermetic sealing of dural and scalp defect. Recently, only few studies of craniocerebral penetrating injuries are published that too involving smaller patients sample sizes; although classic studies in the military and civil situation noticed associated relatively very high mortality and morbidity and psychological as well as economic impact on the affected individual, the family and the health system in providing ongoing care to the sufferers and society at large. Currently various measures are advocated with aim to reduce the incidence of CGI especially in civilian populations. It is highly necessary and immensely urgent to promote research in a neurocritical care of CGI to provide positive impact on improvement of the quality of life and further providing better care and reduction of overall health care cost

Reduction of cardiac imaging tests during the COVID-19 pandemic: The case of Italy. Findings from the IAEA Non-invasive Cardiology Protocol Survey on COVID-19 (INCAPS COVID)

Background: In early 2020, COVID-19 massively hit Italy, earlier and harder than any other European country. This caused a series of strict containment measures, aimed at blocking the spread of the pandemic. Healthcare delivery was also affected when resources were diverted towards care of COVID-19 patients, including intensive care wards. Aim of the study: The aim is assessing the impact of COVID-19 on cardiac imaging in Italy, compare to the Rest of Europe (RoE) and the World (RoW). Methods: A global survey was conducted in May–June 2020 worldwide, through a questionnaire distributed online. The survey covered three periods: March and April 2020, and March 2019. Data from 52 Italian centres, a subset of the 909 participating centres from 108 countries, were analyzed. Results: In Italy, volumes decreased by 67% in March 2020, compared to March 2019, as opposed to a significantly lower decrease (p &lt; 0.001) in RoE and RoW (41% and 40%, respectively). A further decrease from March 2020 to April 2020 summed up to 76% for the North, 77% for the Centre and 86% for the South. When compared to the RoE and RoW, this further decrease from March 2020 to April 2020 in Italy was significantly less (p = 0.005), most likely reflecting the earlier effects of the containment measures in Italy, taken earlier than anywhere else in the West. Conclusions: The COVID-19 pandemic massively hit Italy and caused a disruption of healthcare services, including cardiac imaging studies. This raises concern about the medium- and long-term consequences for the high number of patients who were denied timely diagnoses and the subsequent lifesaving therapies and procedures

International Impact of COVID-19 on the Diagnosis of Heart Disease

Background: The coronavirus disease 2019 (COVID-19) pandemic has adversely affected diagnosis and treatment of noncommunicable diseases. Its effects on delivery of diagnostic care for cardiovascular disease, which remains the leading cause of death worldwide, have not been quantified. Objectives: The study sought to assess COVID-19's impact on global cardiovascular diagnostic procedural volumes and safety practices. Methods: The International Atomic Energy Agency conducted a worldwide survey assessing alterations in cardiovascular procedure volumes and safety practices resulting from COVID-19. Noninvasive and invasive cardiac testing volumes were obtained from participating sites for March and April 2020 and compared with those from March 2019. Availability of personal protective equipment and pandemic-related testing practice changes were ascertained. Results: Surveys were submitted from 909 inpatient and outpatient centers performing cardiac diagnostic procedures, in 108 countries. Procedure volumes decreased 42% from March 2019 to March 2020, and 64% from March 2019 to April 2020. Transthoracic echocardiography decreased by 59%, transesophageal echocardiography 76%, and stress tests 78%, which varied between stress modalities. Coronary angiography (invasive or computed tomography) decreased 55% (p &lt; 0.001 for each procedure). In multivariable regression, significantly greater reduction in procedures occurred for centers in countries with lower gross domestic product. Location in a low-income and lower–middle-income country was associated with an additional 22% reduction in cardiac procedures and less availability of personal protective equipment and telehealth. Conclusions: COVID-19 was associated with a significant and abrupt reduction in cardiovascular diagnostic testing across the globe, especially affecting the world's economically challenged. Further study of cardiovascular outcomes and COVID-19–related changes in care delivery is warranted