17 research outputs found
Capacity, Bandwidth and Available Bandwidth in Wireless Ad Hoc Networks: Definitions and Estimations
Neuromatch Academy: a 3-week, online summer school in computational neuroscience
Neuromatch Academy (https://academy.neuromatch.io; (van Viegen et al., 2021)) was designed as an online summer school to cover the basics of computational neuroscience in three weeks. The materials cover dominant and emerging computational neuroscience tools, how they complement one another, and specifically focus on how they can help us to better understand how the brain functions. An original component of the materials is its focus on modeling choices, i.e. how do we choose the right approach, how do we build models, and how can we evaluate models to determine if they provide real (meaningful) insight. This meta-modeling component of the instructional materials asks what questions can be answered by different techniques, and how to apply them meaningfully to get insight about brain function
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
Control de admisión para redes móviles AD HOC con base en estimación de ancho de banda disponible
The admission control algorithms in wired networks
can monitor traf c on each of the links
point-to-point in order to determine the available
bandwidth for the ows along different routes
and base their decision the difference between the
available bandwidth and the bandwidth required.
Unfortunately, this is not possible in a mobile
ad hoc network (MANET) for several reasons,
among which two stands out: (1) In the MANET,
a transfer between two adjacent nodes consumes
the bandwidth of many neighbors, which dif cult
to estimate the available bandwidth. (2) A node
that supports has an effect on the network that
goes far beyond reducing the bandwidth available
in a predictable amount, on the contrary, it can
affect the spatial distribution of existing ows and
the likelihood of collision. In these conditions, it
is easy for an admission control algorithm to determine
the magnitude of the ows should be admitted
to exploit the resources of communication
without saturating the network. This is a re ection
article where we discuss some major issues
associated with the interaction between these two
fundamental problems and propose a new approach
to investigation.Los algoritmos de control de admisión en redes
alambradas pueden monitorear el trá co sobre
cada uno de los enlaces punto-a-punto con el n
de determinar el ancho de banda disponible para
los ujos a lo largo de diferentes rutas y basar su
decisión en la diferencia entre el ancho de banda
disponible y el ancho de banda requerido. Infortunadamente,
esto no es posible en una red móvil ad
hoc (MANET) por varias razones, entre las que se
destacan dos: (1) en la MANET, una transmisión
entre dos nodos adyacentes consume el ancho de
banda de muchos nodos vecinos, lo cual di culta
la estimación del ancho de banda disponible. (2)
Un nodo que se admite tiene un efecto sobre la
red que va mucho más allá de reducir el ancho
de banda disponible en una cantidad previsible; a contrario, puede afectar la distribución espacial de
los ujos existentes asà como las probabilidades
de colisión. En estas condiciones, no es fácil para
un algoritmo de control de admisión determinar
la magnitud de los ujos que deben ser admitidos
para aprovechar los recursos de comunicación
sin saturar la red. Este es un artÃculo de re exión
en el que discutimos algunos de los principales
aspectos asociados con la interacción entre estos
dos problemas fundamentales y proponemos un
nuevo enfoque de investigación al respect
Control de admisión para redes móviles AD HOC con base en estimación de ancho de banda disponible
Los algoritmos de control de admisión en redes alambradas pueden monitorear el tráfico sobre cada uno de los enlaces punto-a-punto con el fin de determinar el ancho de banda disponible para los flujos a lo largo de diferentes rutas y basar su decisión ...
On the Implementation of a Capacity Estimator for Wireless Ad Hoc Networks
Abstract—End-to-end capacity is a useful metric for network applications such as traffic engineering, QoS verification, peer-topeer file distribution, video/audio streaming, admission control, etc. Although several tools have been developed to estimate endto-end capacity and available bandwidth in wired networks, estimators for wireless ad-hoc networks are still to be developed. The paper briefly describes the model of a new capacity estimation tool for wireless ad-hoc networks. Then, it discusses two critical aspects in the implementation of any estimation tool: time stamping packets and clock synchronization. The paper details how to time stamp packets under the Linux and Windows operating systems, and a describes a regression-based mechanism that eliminates measurement errors due to clock drifts. The time stamping methods and the regression algorithm are implemented in the capacity estimator, which shows accurate capacity estimations. I