Vibrational testing of optical fiber connector joints

An experimental study was performed to determine the effects of vibration on the propagation of light through SMA- and ST-type fiber-optic connectors. A multimode, fiber-optic link was vibrated from 0 to 10,000 Hz at a constant peak acceleration along the connector transverse and longitudinal axes. All other environmental parameters were ambient. Transfer characteristics through the connection were examined as a function of vibrational frequency using both laser and light-emitting diode (LED) light to illuminate the system. Slight differences in operation between the SMA and ST connectors were observed with no appreciative attenuation as a result of vibration. Vibration did cause the constant-amplitude input light to be modulated in the connector; however, the amplitude of vibration-induced noise was less than 3 standard deviations from the mean

Search and Tracking Algorithms for Rapidly Moving Mobiles

With the advent of wireless technology and laptops, mobility is an important area of research. A fundamental problem in this area is the delivery of messages to a moving mobile. Current solutions work correctly only for slowly moving nodes that stay in one location long enough for tracking to stabilize. In this paper we consider the problem of message delivery to rapidly moving mobile units. With these algorithms, we introduce a new method for designing algorithms based on the paradigm of considering a mobile unit as a message, and adapting traditional message passing algorithms to mobility. Our first algorithm is based on tracking and can be efficient when the path of the mobile node exhibits considerable locality. While it uses the Dijkstra-Scholten algorithm for diffusing computations as a point of departure, the final algorithm adds a number of mechanisms. Our second example is a search algorithm based on transforming the classic Chandy-Lamport snapshot algorithm. The algorithm generalizes to multicasting to a set of rapidly moving mobiles. Both our algorithms are based on the assumption that messages and mobiles travel through the same FIFO channels. We show how to enforce this assumption by modifying existing handover protocols

Differential effects of calcium channel blockers on size selectivity of proteinuria in diabetic glomerulopathy

Differential effects of calcium channel blockers on size selectivity of proteinuria in diabetic glomerulopathy.BackgroundCalcium channel blockers (CCBs) are known to have differential effects on both changes in proteinuria as well as progression of diabetic nephropathy. No clinical study, however, has evaluated whether the differential antiproteinuric effects of CCBs may be explained by their effect on glomerular membrane permeability. We, therefore, tested the hypothesis that certain subclasses of CCBs reduce proteinuria by changing size selectivity of the glomerular membrane, hence changing its permeability.MethodsTwenty-one patients with type 2 diabetes and the presence of nephropathy with hypertension were randomized to receive either diltiazem CD or nifedipine GITS after baseline data for mean systolic and diastolic pressure, urinary protein excretion, glomerular filtration rate, renal plasma flow, neutral dextran and IgG clearances were obtained. Glomerular filtration rate, renal plasma flow, neutral dextran and IgG clearance were measured every three months, arterial pressure and heart rate every month. Patients were followed for 21months.ResultsAt 21months, both patient groups had similar levels of blood pressure control, however, only the diltiazem group had a change in proteinuria (4 ± 10%Δ, nifedipine vs. -57 ± 18%Δ, diltiazem; P < 0.001) with improvement in glomerular size selectivity and change in IgG clearance.ConclusionsThese data support the hypothesis that CCBs that provide sustained reductions in proteinuria do so, in part, by improving glomerular size permselectivity

An Algorithm for Message Delivery in a Micromobility Environment

With recent advances in wireless communication and the ubiquity of laptops, mobile computing has become an important research area. An essential problem in mobile computing is the delivery of a message from a source to either a single mobile node, unicast, or to a group of mobile nodes, multicast. Standard solutions proposed for macromobility (Mobile IP) and micromobility (cellular phones) for the unicast problem rely on tracking the mobile node. Tracking solutions scale badly when mobile nodes move frequently, and do not generalize well to multicast delivery. Our paper proposes a new message delivery algorithm for micromobility based on a modification of classical snapshot algorithms. Our algorithm requires no tracking, provides stronger guarantees than existing protocols in micromobility, and generalizes easily to multicasting. Besides a particular solution to the delivery problem, our approach offers a new strategy for transferring established results from distributed computing to mobile computing. The general idea is to treat mobile nodes as messages that roam across the fixed network structure and to leverage off existing distributed algorithms that compute information about messages

Algorithms for Message Delivery in a Micromobility Environment

As computing components get smaller and people become accustomed to having computational power at their disposal at any time, mobile computing is developing as an important research area. One of the fundamental problems in mobility is maintaining connectivity through message passing as the user moves through the network. This is usually accomplished in one of two ways: search or tracking. In search, an algorithm hunts the mobile unit through the network each time a message is to be delivered, while in tracking, a specific home keeps up to date information about the current location of the mobile unit. Our paper proposes two message delivery algorithms based on these two paradigms of mobility. In general, our approach is to adopt existing algorithms from distributed computing to solve the problem of message delivery in the mobile setting, allowing us to leverage off existing knowledge about these algorithms and extensive research from distributed computing. The transformation from distributed to mobile computing is accomplished by treating the mobile units as messages that roam across the fixed network structure. First we show how snapshot algorithms can be adapted to perform message delivery through search, and then how the model of diffusing computations can be altered to track a mobile unit

Tracking Mobile Units for Dependable Message Delivery

As computing components get smaller and people become accustomed to having computational power at their disposal at any time, mobile computing is developing as an important research area. One of the fundamental problems in mobility is maintaining connectivity through message passing as the user moves through the network. An approach to this is to have a single home node constantly track the current location of the mobile unit and forward messages to this location. One problem with this approach is that during the update to the home agent after movement, messages are often dropped, especially in the case of frequent movement. In this paper, we present a new algorithm which uses a home agent, but maintains information regarding a subnet within which the mobile unit must be present. We also present a reliable message delivery algorithm which is superimposed on the region maintenance algorithm. Our strategy is based on ideas from diffusing computations as first proposed by Dijkstra and Scholten. Finally, we present a second algorithm which limits the size of the subnet by keeping only a path from the home node to the mobile unit

An Algorithm for Message Delivery to Mobile Units

With recent advances in wireless communication and the ubiquity of laptops, mobile computing has become an important research area. An essential problem in mobile computing is the delivery of a message from a source to either a single mobile node, unicast, or to a group of mobile nodes, multicast. Standard solutions used in Mobile IP and cellular phones for the unicast problem rely on tracking the mobile unit. Tracking solutions scale badly when mobile nodes move frequently, and do not generalize well to multicast delivery. Our paper proposes a new message delivery algorithm for micromobility based on a modification of classical snapshot algorithms and includes a proof outline using the UNITY logic. Our algorithm requires no tracking, provides stronger guarantees than existing protocols in micromobility, and generalizes easily to multicasting. Besides a particular solution to the delivery problem, our approach offers a new strategy for transferring established results from distributed computing to mobile computing. The general idea is to treat mobile nodes as messages that roam across the fixed network structure and to leverage off existing distributed algorithms that compute information about messages