Impact of employee motivation on passenger satisfaction levels – A case study in the state of Karnataka (India)

Institute of Transport and Logistics Studies. Faculty of Economics and Business. The University of Sydne

Software-defined datacenter network debugging

Software-defined Networking (SDN) enables flexible network management, but as networks evolve to a large number of end-points with diverse network policies, higher speed, and higher utilization, abstraction of networks by SDN makes monitoring and debugging network problems increasingly harder and challenging. While some problems impact packet processing in the data plane (e.g., congestion), some cause policy deployment failures (e.g., hardware bugs); both create inconsistency between operator intent and actual network behavior. Existing debugging tools are not sufficient to accurately detect, localize, and understand the root cause of problems observed in a large-scale networks; either they lack in-network resources (compute, memory, or/and network bandwidth) or take long time for debugging network problems. This thesis presents three debugging tools: PathDump, SwitchPointer, and Scout, and a technique for tracing packet trajectories called CherryPick. We call for a different approach to network monitoring and debugging: in contrast to implementing debugging functionality entirely in-network, we should carefully partition the debugging tasks between end-hosts and network elements. Towards this direction, we present CherryPick, PathDump, and SwitchPointer. The core of CherryPick is to cherry-pick the links that are key to representing an end-to-end path of a packet, and to embed picked linkIDs into its header on its way to destination. PathDump is an end-host based network debugger based on tracing packet trajectories, and exploits resources at the end-hosts to implement various monitoring and debugging functionalities. PathDump currently runs over a real network comprising only of commodity hardware, and yet, can support surprisingly a large class of network debugging problems with minimal in-network functionality. The key contributions of SwitchPointer is to efficiently provide network visibility to end-host based network debuggers like PathDump by using switch memory as a "directory service" — each switch, rather than storing telemetry data necessary for debugging functionalities, stores pointers to end hosts where relevant telemetry data is stored. The key design choice of thinking about memory as a directory service allows to solve performance problems that were hard or infeasible with existing designs. Finally, we present and solve a network policy fault localization problem that arises in operating policy management frameworks for a production network. We develop Scout, a fully-automated system that localizes faults in a large scale policy deployment and further pin-points the physical-level failures which are most likely cause for observed faults

Contra: A Programmable System for Performance-aware Routing

We present Contra, a system for performance-aware routing that can adapt to traffic changes at hardware speeds. While existing work has developed point solutions for performance-aware routing on a fixed topology (e.g., a Fattree) with a fixed routing policy (e.g., use least utilized paths), Contra can be configured to operate seamlessly over any network topology and a wide variety of sophisticated routing policies. Users of Contra write network-wide policies that rank network paths given their current performance. A compiler then analyzes such policies in conjunction with the network topology and decomposes them into switch-local P4 programs, which collectively implement a new, specialized distance-vector protocol. This protocol generates compact probes that traverse the network, gathering path metrics to optimize for the user policy dynamically. Switches respond to changing network conditions at hardware speeds by routing flowlets along the best policy-compliant paths. Our experiments show that Contra scales to large networks, and that in terms of flow completion times, it is competitive with hand-crafted systems that have been customized for specific topologies and policies

Rare Manifestation of a Rare Disease, Acute Liver Failure in Adult Onset Still’s Disease: Dramatic Response to Methylprednisolone Pulse Therapy—A Case Report and Review

Adult onset Still’s disease (AOSD) is a rare systemic inflammatory disorder of unknown etiology. It is characterized by daily fevers, arthralgias or arthritis, typical skin rash, and leukocytosis. Hepatic involvement is frequently observed in the course of AOSD with mildly elevated transaminases and/or hepatomegaly. Fulminant hepatic failure, occasionally requiring urgent liver transplantation, is a rare manifestation of AOSD. Here, we present a case of 22-year-old woman with no significant medical history who initially came with fever, arthralgias, myalgias, generalized weakness, and sore throat. Laboratory data showed mildly elevated transaminases and markedly elevated ferritin levels. She was diagnosed with AOSD based on Yamaguchi diagnostic criteria and was started on prednisone. Three months later, while she was on tapering dose of steroid, she presented with fever, abdominal pain, jaundice, and markedly elevated transaminases. Extensive workup excluded all potential causes of liver failure. She was diagnosed with AOSD associated acute liver failure (ALF). Intravenous (IV) methylprednisolone pulse therapy was started, with dramatic improvement in liver function. Our case demonstrated that ALF can present as a complication of AOSD and IV mega dose pulse methylprednisolone therapy can be employed as a first-line treatment in AOSD associated ALF with favorable outcome

ADF/cofilin-driven actin dynamics in early events of Leishmania cell division

ADF/cofilin is an actin-dynamics-regulating protein that is required for several actin-based cellular processes such as cell motility and cytokinesis. A homologue of this protein has recently been identified in the protozoan parasite Leishmania, which has been shown to be essentially required in flagellum assembly and cell motility. However, the role of this protein in cytokinesis remains largely unknown. We show here that deletion of the gene encoding ADF/cofilin in these organisms results in several aberrations in the process of cell division. These aberrations include delay in basal body and kinetoplast separation, cleavage furrow progression and flagellar pocket division. In addition to these changes, the intracellular trafficking and actin dynamics are also adversely affected. All these abnormalities are, however, reversed by episomal complementation. Together, these results indicate that actin dynamics regulates early events in Leishmania cell division

Improvement of radar ice-thickness measurements of Greenland outlet glaciers using SAR processing

This is the published version, also available here: http://dx.doi.org/10.3189/172756402781816852.Extensive aircraft-based radar ice-thickness measurements over the interior and outlet-glacier regions of the Greenland ice sheet have been obtained by the University of Kansas since 1993, with the latest airborne surveys conducted in May 2001. The radar has evolved during this period to a highly versatile system capable of characterizing ice thickness over a wide variety of ice-sheet conditions. Before 1997, the digital system was limited, only capable of storing incoherent data or coherent data with a very large number of presumed signals at a low pulse-repetition frequency. In 1998, the radar was upgraded with modern components allowing coherent data to be stored with a small number of presumed returns for 1024 range cells at a high pulse-repetition frequency.The new data on ice thickness of Greenland outlet glaciers are archived and made available to the scientific community in the form of radar echograms and derived ice thickness at http://tornado.rsl.ukans.edu/Greenlanddata.htm. The U.S. National Snow and Ice Data Center (NSIDC) also provides a link to these data, and NSIDC will eventually serve as the permanent archive of these data. Improvements in radar sensitivity in outlet-glacier regions have been achieved by collecting coherent radar data and applying various signal-processing techniques. Deep outlet-glacier channels that were previously unresolved with incoherent data can now be mapped using a coherent signal, signal conditioning and synthetic aperture radar (SAR) processing

Trafficking activity of myosin XXI is required in assembly of Leishmania flagellum

Actin-based myosin motors have a pivotal role in intracellular trafficking in eukaryotic cells. The parasitic protozoan organism Leishmania expresses a novel class of myosin, myosin XXI (Myo21), which is preferentially localized at the proximal region of the flagellum. However, its function in this organism remains largely unknown. Here, we show that Myo21 interacts with actin, and its expression is dependent of the growth stage. We further reveal that depletion of Myo21 levels results in impairment of the flagellar assembly and intracellular trafficking. These defects are, however, reversed by episomal complementation. Additionally, it is shown that deletion of the Myo21 gene leads to generation of ploidy, suggesting an essential role of Myo21 in survival of Leishmania cells. Together, these results indicate that actin-dependent trafficking activity of Myo21 is essentially required during assembly of the Leishmania flagellum

IoT MUD enforcement in the edge cloud using programmable switch

Targeted data breaches and cybersecurity attacks involving IoT devices are becoming ever more concerning. To combat these threats and risks, the IETF standardized Manufacturer Usage Description (MUD), which allows IoT device vendors to specify the intended communication patterns (MUD profile) of an IoT device. MUD profile enables validation of the actual communication pattern of an IoT device with the intended behavior at run-time. However, the MUD specification was primarily intended for enforcement at the Local Area Network (LAN) of the IoT device, thus fragmenting the solution across multiple heterogeneous networks. MUD enforcement at higher levels in the network hierarchy (e.g., private edge for enterprise networks) eases security policy management and reduces processing overheads on the existing security infrastructure. To realize MUD enforcement at the edge, there are mainly two challenges: (1) How to identify an IoT device at the edge so that enforcing device-specific MUD profile on the IoT traffic is possible. (2) How to scale MUD enforcement to a large network of IoT devices. In this paper, we present our approach to address these challenges and validate IoT device communication at the edge. In order to scale MUD enforcement to a large IoT network, we leverage multi-stage pipeline architecture and stateful ALUs of P4 programmable switch and process IoT traffic in the dataplane. © 2022 ACM