The state of peer-to-peer network simulators

Networking research often relies on simulation in order to test and evaluate new ideas. An important requirement of this process is that results must be reproducible so that other researchers can replicate, validate and extend existing work. We look at the landscape of simulators for research in peer-to-peer (P2P) networks by conducting a survey of a combined total of over 280 papers from before and after 2007 (the year of the last survey in this area), and comment on the large quantity of research using bespoke, closed-source simulators. We propose a set of criteria that P2P simulators should meet, and poll the P2P research community for their agreement. We aim to drive the community towards performing their experiments on simulators that allow for others to validate their results

Socio-Economic Inequalities in the Use of Postnatal Care in India

OBJECTIVES: First, our objective was to estimate socio-economic inequalities in the use of postnatal care (PNC) compared with those in the use of care at birth and antenatal care. Second, we wanted to compare inequalities in the use of PNC between facility births and home births and to determine inequalities in the use of PNC among mothers with high-risk births. METHODS AND FINDINGS: Rich-poor ratios and concentration indices for maternity care were estimated using the third round of the District Level Household Survey conducted in India in 2007-08. Binary logistic regression models were used to examine the socio-economic inequalities associated with use of PNC after adjusting for relevant socio-economic and demographic characteristics. PNC for both mothers and newborns was substantially lower than the care received during pregnancy and child birth. Only 44% of mothers in India at the time of survey received any care within 48 hours after birth. Likewise, only 45% of newborns received check-up within 24 hours of birth. Mothers who had home births were significantly less likely to have received PNC than those who had facility births, with significant differences across the socio-economic strata. Moreover, the rich-poor gap in PNC use was significantly wider for mothers with birth complications. CONCLUSIONS: PNC use has been unacceptably low in India given the risks of mortality for mothers and babies shortly after birth. However, there is evidence to suggest that effective use of pregnancy and childbirth care in health facilities led to better PNC. There are also significant socio-economic inequalities in access to PNC even for those accessing facility-based care. The coverage of essential PNC is inadequate, especially for mothers from economically disadvantaged households. The findings suggest the need for strengthening PNC services to keep pace with advances in coverage for care at birth and prenatal services in India through targeted policy interventions

Tweaking of Peripheral Moieties in Catalytic Amyloid for Modulating Hydrogel Strength and Hydrolase Activity

The de novo design and synthesis of peptide-based biocatalysts that can mimic the activity of natural enzymes is an exciting field with unique opportunities and challenges. In a natural enzyme, the active site is composed of an assembly of different amino acid residues, often coordinated with a metal ion. A metalloenzyme’s catalytic activity results from the dynamic and concerted interplay of various interactions among the residues and metal ions. Aiming to mimic such enzymes, simple peptide fragments, drawing structural inspiration from natural enzymes, can be utilized as a model. In our effort to mimic a metal-containing hydrolase, we designed peptide amphiphiles (PA) 1 and 2 with a terminal histidine having amide and acid functionalities, respectively, at its C-terminal, imparting differential ability to coordinate with Zn and Cu ions. The PAs demonstrate remarkable self-assembly behavior forming excellent nanofibers. Upon coordination with metal ions, depending on the coordination site the nanofibers become rigidified or weakened. Rheological studies revealed excellent mechanical properties of the hydrogels formed by the PAs and the PA–metal co-assemblies. Using such co-assemblies, we mimic hydrolase activity against a p-nitrophenyl acetate (p-NPA) substrate. Michaelis–Menten’s enzyme kinetic parameters indicated superior catalytic activity of 2 with Zn amongst all the assemblies

Performance and Quality-of-Service Analysis of a Live P2P Video Multicast Session on the Internet

Abstract—We evaluate the performance of a large-scale live P2P video multicast session comprising more than 120, 000 peers on the Internet. Our analysis highlights P2P video multicast characteristics such as high bandwidth requirements, high peer churn, low peer persistence in the P2P multicast system, significant variance in the media stream quality delivered to peers, relatively large channel start times, and flash crowd effects of popular video content. Our analysis also indicates that peers are widely spread across the IP address space, spanning dozens of countries and hundreds of ISPs and Internet ASes. As part of the P2P multicast evaluation several QoS measures such as fraction of stream blocks correctly received, number of consecutive stream blocks lost, and channel startup time across peers. We correlate the observed quality with the underlying network and with peer behavior, suggesting several avenues for optimization and research in P2P video multicast systems. I