"The War for the Fare": How Driver Compensation Affects Bus System Performance

Two systems of bus driver compensation exist in Santiago, Chile. Most drivers are paid per passenger transported, while a second system compensates other drivers with a fixed wage. Compared with fixed-wage drivers, per-passenger drivers have incentives to engage in "La Guerra por el Boleto" ("The War for the Fare"), in which drivers change their driving patterns to compete for passengers. This paper takes advantage of a natural experiment provided by the coexistence of these two compensation schemes on similar routes in the same city. Using data on intervals between bus arrivals, we find that the fixed-wage contract leads to more bunching of buses, and hence longer average passenger wait times. The per-passenger drivers are assisted by a group of independent information intermediaries called "sapos" who earn their living by standing at bus stops, recording arrival times, and selling the information to subsequent drivers who drive past. We find that a typical bus passenger in Santiago waits roughly 10% longer for a bus on a fixed-wage route relative to an incentive-contract route. However, the incentives also lead drivers to drive noticeably more aggressively, causing approximately 67% more accidents per kilometer driven. Our results have implications for the design of incentives in public transportation systems.

Perceptually smooth timbral guides by state-space analysis of phase-vocoder parameters

Sculptor is a phase-vocoder-based package of programs that allows users to explore timbral manipulation of sound in real time. It is the product of a research program seeking ultimately to perform gestural capture by analysis of the sound a performer makes using a conventional instrument. Since the phase-vocoder output is of high dimensionality — typically more than 1,000 channels per analysis frame—mapping phase-vocoder output to appropriate input parameters for a synthesizer is only feasible in theory

Ordination of Trace Metals in Syacium papillosum (Dusky Flounder) from the Eastern Gulf of Mexico

Variations in the metal contents (Ba, Cd, Cr, Cu, Fe, Ni, Pb, V, and Zn) in the skeletal flesh of the demersal fish Syacium papillosum from 12 stations on the relatively unpolluted Mississippi, Alabama, and Florida continental margin are investigated with the aid of a-mode ordination techniques. Gradient analysis on the station-season ordination shows that Ba, Cu, and Ni explain most of the normal variation. Of these metals only Cu and Ni increased from summer to winter; this increase may be related to decreased metabolism. The decrease of Ba (and Cd) in winter may be diet controlled. Based on ordination synthetic indices, nonparametric statistical testing indicates that the winter trace metal concentrations are multivariately distinct from those of the fall and summer sampling suites; the latter are not statistically distinguishable. The trace metal concentrations measured in the demersal fish specimens are weakly correlated (positive) with the metal concentrations measured in the weak acid digest of the study area bottom sediments

Advanced modulation technology development for earth station demodulator applications. Coded modulation system development

A jointly optimized coded modulation system is described which was designed, built, and tested by COMSAT Laboratories for NASA LeRC which provides a bandwidth efficiency of 2 bits/s/Hz at an information rate of 160 Mbit/s. A high speed rate 8/9 encoder with a Viterbi decoder and an Octal PSK modem are used to achieve this. The BER performance is approximately 1 dB from the theoretically calculated value for this system at a BER of 5 E-7 under nominal conditions. The system operates in burst mode for downlink applications and tests have demonstrated very little degradation in performance with frequency and level offset. Unique word miss rate measurements were conducted which demonstrate reliable acquisition at low values of Eb/No. Codec self tests have verified the performance of this subsystem in a stand alone mode. The codec is capable of operation at a 200 Mbit/s information rate as demonstrated using a codec test set which introduces noise digitally. The measured performance is within 0.2 dB of the computer simulated predictions. A gate array implementation of the most time critical element of the high speed Viterbi decoder was completed. This gate array add-compare-select chip significantly reduces the power consumption and improves the manufacturability of the decoder. This chip has general application in the implementation of high speed Viterbi decoders

Feedback-enhanced algorithm for aberration correction of holographic atom traps

We show that a phase-only spatial light modulator can be used to generate non-trivial light distributions suitable for trapping ultracold atoms, when the hologram calculation is included within a simple and robust feedback loop that corrects for imperfect device response and optical aberrations. This correction reduces the discrepancy between target and experimental light distribution to the level of a few percent (RMS error). We prove the generality of this algorithm by applying it to a variety of target light distributions of relevance for cold atomic physics.Comment: 5 pages, 4 figure

Descriptions of WHOI sediment cores : volume 5

This report supplements Volumes 1-4 of the core descriptions published previously in this sequence (Johnson and Driscoll, 1975). It contains visual descriptions and smear slide analyses for all cores received in the geological samples collection of the Woods Hole Oceanographic Institution between November, 1973 and November, 1976. Approximately 368 sample localities from the North Atlantic, Mediterranean, and South Atlantic are represented. Charts of ships' tracks and updated computer listings of all cores in the W.H.O.I. collection are also included.Prepared for the Office of Naval Research under Contract N00014-74-C0262, NR 083-004; and for the National Science Foundation under Grant OCE76-81488