A Visit to Taxicab Geometry

ERIC Educational Resources Information Center

Hanson, J. R.

2012-01-01

The taxi metric is introduced, compared to the Euclidean metric, and used to define the taxi circle. For all pairs of points "A" and "B" the set of points equally distant under the taxi metric to "A" and to "B" is determined. For any triangle these sets are used to either find the centre of a taxi circle that can circumscribe the triangle or to…

75 FR 26761 - National Cancer Institute; Notice of Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-12

... Group(s); and Budget Presentations; Reports of Special Initiatives; RFA and RFP Concept Reviews; and... campus. All visitor vehicles, including taxicabs, hotel, and airport shuttles will be inspected before...

76 FR 62422 - National Cancer Institute; Notice of Meetings

Federal Register 2010, 2011, 2012, 2013, 2014

2011-10-07

... Groups; and Budget Presentations; Reports of Special Initiatives; RFA and RFP Concept Reviews; and... taxicabs, hotel, and airport shuttles will be inspected before being allowed on campus. Visitors will be...

75 FR 63494 - National Cancer Institute; Notice of Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2010-10-15

... Group(s); and Budget Presentations; Reports of Special Initiatives; RFA and RFP Concept Reviews; and... taxicabs, hotel, and airport shuttles will be inspected before being allowed on campus. Visitors will be...

78 FR 5192 - National Cancer Institute; Notice of Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2013-01-24

... Review Group(s); and Budget Presentations; Reports of Special Initiatives; RFA and RFP Concept Reviews... entrance onto the NIH campus. All visitor vehicles, including taxicabs, hotel, and airport shuttles will be...

76 FR 26310 - National Cancer Institute; Notice of Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2011-05-06

... Group(s); and Budget Presentations. Place: National Institutes of Health, Building 31, 31 Center Drive... entrance onto the NIH campus. All visitor vehicles, including taxicabs, hotel, and airport shuttles will be...

29 CFR 778.217 - Reimbursement for expenses.

Code of Federal Regulations, 2010 CFR

2010-07-01

.... (2) The actual or reasonably approximate amount expended by an employee in purchasing, laundering or... expenses, such as taxicab fares, incurred while traveling on the employer's business. (4) “Supper money”, a...

2006 public transportation fact book

DOT National Transportation Integrated Search

2006-04-01

This book includes only public transportation data and excludes taxicab, unregulated jitney, school, sightseeing, intercity, charter, : military, and non-public service (e.g., governmental and corporate shuttles), and special application systems (e.g...

2004 public transportation fact book

DOT National Transportation Integrated Search

2004-03-01

This book includes only public transportation data and excludes taxicab, unregulated jitney, school, sightseeing, intercity, charter, : military, and non-public service (e.g., governmental and corporate shuttles), and special application systems (e.g...

2005 public transportation fact book

DOT National Transportation Integrated Search

2005-04-01

This book includes only public transportation data and excludes taxicab, unregulated jitney, school, sightseeing, intercity, charter, military, and non-public service (e.g., governmental and corporate shuttles), and special application systems (e.g.,...

2007 public transportation fact book

DOT National Transportation Integrated Search

2007-05-01

This book includes only public transportation data and excludes taxicab, unregulated jitney, school, sightseeing, intercity, charter, : military, and services not available to the general public, or segments of the general public (e.g., governmental ...

29 CFR 778.217 - Reimbursement for expenses.

Code of Federal Regulations, 2014 CFR

2014-07-01

... expenses, such as taxicab fares, incurred while traveling on the employer's business. (4) “Supper money”, a... or furnishes the facilities (such as free lunches or free housing), the amount paid to the employee...

75 FR 9912 - Clinical Center; Notice of Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2010-03-04

..., 2010. Open: 10 a.m. to 1:15 p.m. Agenda: To review the FY11 Clinical Center Budget. Place: National..., including taxicabs, hotel, and airport shuttles will be inspected before being allowed on campus. Visitors...

77 FR 12602 - Clinical Center Notice of Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2012-03-01

..., 2012. Time: 10 a.m. to 1:15 p.m. Agenda: To review the FY13 Clinical Center Budget. Place: National... procedures for entrance onto the NIH campus. All visitor vehicles, including taxicabs, hotel, and airport...

76 FR 13196 - Clinical Center; Notice of Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2011-03-10

..., 2011. Open: 10 a.m. to 1:15 p.m. Agenda: To review the FY12 Clinical Center Budget. Place: National..., including taxicabs, hotel, and airport shuttles will be inspected before being allowed on campus. Visitors...

User-Side Subsidies for the Elderly and Handicapped in Lawrence, Massachusetts

DOT National Transportation Integrated Search

1984-06-01

Funding provided by the Service and Methods Demonstration (SMD) Program of the U.S. Department of Transportation, Urban Mass Transportation Administration, was used to subsidize the bus, taxicab, and wheelchair lift-equipped van travel of elderly and...

48 CFR 22.1003-5 - Some examples of contracts covered.

Code of Federal Regulations, 2010 CFR

2010-10-01

... CFR 4.130 for additional examples): (a) Motor pool operation, parking, taxicab, and ambulance services...) Certain specialized services requiring specific skills, such as drafting, illustrating, graphic arts..., engines, electrical motors, vehicles, and electronic, office and related business and construction...

Taxi Scrip Program in Seattle, Washington

DOT National Transportation Integrated Search

1982-09-01

The Municipality of Metropolitan Seattle (Metro) took over a taxi user-side subsidy program from the City of Seattle in December 1978, which was based on the sale of discounted taxicab scrip. Metro expanded the program, raised the discount, and condu...

Late-Night Shared-Ride Taxi Transit in Ann Arbor, MI

DOT National Transportation Integrated Search

1984-10-01

The Ann Arbor Transportation Authority introduced Night Ride, a late-night shared-ride taxi transit service, in mid-March 1982. The service was provided through a contract with a local taxicab company and funded through a demonstration grant from the...

Taxi Regulatory Revision in Oakland and Berkeley, California : Two Case Studies

DOT National Transportation Integrated Search

1983-06-01

A case study was performed of regulatory changes pertaining to taxicabs in Oakland and neighboring Berkeley, CA. In Oakland rates were approximately doubled and limits on the number of taxi permits removed. Companies were allowed to levy a per-trip s...

Effects of Taxi Regulatory Revision in Seattle, Washington

DOT National Transportation Integrated Search

1983-05-01

In May 1979 the City of Seattle enacted license code revisions affecting taxicabs. Entry is opened to both fleets and independents and there is no limit on total licenses or the number of licenses a single operator may obtain. Open rate setting repla...

Taxi Regulatory Revision in Seattle, Washington : Background and Implementation

DOT National Transportation Integrated Search

1980-01-01

In May 1979 the City of Seattle enacted license code revisions affecting taxicabs. Entry is opened to both fleets and independents and there is no limit on total licenses or the number of licenses a single operator may obtain. Open rate setting repla...

Exit and Voice: Organizational Loyalty and Dispute Resolution Strategies

ERIC Educational Resources Information Center

Hoffmann, Elizabeth A.

2006-01-01

This study compares workplace dispute resolution strategies (exit, voice and toleration) in matched pairs of conventional and worker-owned cooperative organizations operating in three industries--coal mining, taxicab driving and organic food distribution. Building on Hirschman's classic exit, voice and loyalty thesis, this research demonstrates…

22 CFR Appendix E to Part 62 - Unskilled Occupations

Code of Federal Regulations, 2011 CFR

2011-04-01

... Cleaners (10) Chauffeurs and Taxicab Drivers (11) Cleaners, Hotel and Motel (12) Clerks, General (13) Clerks, Hotel (14) Clerks and Checkers, Grocery Stores (15) Clerk Typist (16) Cooks, Short Order (17... Operators (21) Floorworkers (22) Groundskeepers (23) Guards (24) Helpers, any industry (25) Hotel Cleaners...

75 FR 17794 - Medallion Financial Corp.; Notice of Application

Federal Register 2010, 2011, 2012, 2013, 2014

2010-04-07

....\\1\\ The Company is a specialty finance company that has a leading position in originating, acquiring, and servicing loans that finance taxicab medallions and various types of commercial businesses. The... NASDAQ Global Select Market under the symbol ``TAXI.'' As of May 5, 2009, there were 17,565,771 shares of...

29 CFR 778.217 - Reimbursement for expenses.

Code of Federal Regulations, 2011 CFR

2011-07-01

... expended by an employee in purchasing supplies, tools, materials, or equipment on behalf of his employer... approximate amount expended by an employee, who is traveling “over the road” on his employer's business, for... expenses, such as taxicab fares, incurred while traveling on the employer's business. (4) “Supper money”, a...

Gifted Mathematicians Constructing Their Own Geometries--Changes in Knowledge and Attitude.

ERIC Educational Resources Information Center

Shillor, Irith

1997-01-01

Using Taxi-Cab Geometry (a non-Euclidean geometry program) as the starting point, 14 mathematically gifted British secondary students (ages 12-14) were asked to consider the differences between Euclidean and Non-Euclidean geometries, then to construct their own geometry and to consider the non-Euclidean elements within it. The positive effects of…

Remembering Kate and Kathy: Two Passionate Youth Librarians Leave Behind a Lasting Legacy

ERIC Educational Resources Information Center

Smith, Vicky

2009-01-01

For children's book lovers, the world was infinitely glorious on Monday, January 26, 2009, as the winners of the American Library Association's (ALA) awards were announced at the midwinter meeting in Denver. But two days later, a drunk driver slammed into a taxicab, killing two children's librarians as they were on their way to the Denver…

Taxi-cabs as Subjects for a Population Study

ERIC Educational Resources Information Center

Bishop, J. A.; Bradley, J. S.

1972-01-01

Describes the use of capture-recapture techniques to estimate the population of taxis in Liverpool and demonstrates the points of similarity to animal population estimation. Considers advantages of studying taxis rather than organisms in introductory studies of the techniques. (AL)

Telemedicine and the sharing economy: the "Uber" for healthcare.

PubMed

Miller, Brian J; Moore, Derek W; Schmidt, Chester W

2016-12-01

Telehealth platforms, which include both competitors and complements to traditional care delivery, will offer many benefits for both consumers and clinicians, and may promote increased specialization and competition in service delivery. Traditional medical services providers face a challenge similar to that faced by traditional taxicabs after Uber entered the marketplace: how to compete with a connection services platform that threatens to disrupt existing, regulated, and licensed service providers.

Psychology of Intelligence Analysis

DTIC Science & Technology

1999-01-01

information. Each neuron has octopus - like arms called axons and dendrites. Electrical impulses flow through these arms and are ferried by...information rings a bell, the bell cannot be unrung. The ambiguity of most real-world situations contributes to the operation of this perseverance...Potomac, MD: Lawrence Erlbaum Associates, 1976), pp. 177-78. 147. This is a modified version, developed by Frank J. Stech, of the blue and green taxicab

Discussion Material for Small Unit Leaders: Issues of Battlefield Ethics and Leadership

DTIC Science & Technology

2008-01-01

they may feel comfortable approaching him and asking for clarification of the incident. Because they did not witness the incident, the Platoon...Company XO took command of the scene. Visibly angry, he shouted at the Squad Leader to take some Marines and “clear out those shooters.” The...west he heard shouts and then a brief period of high volume small arms fire. Running to the scene, the Platoon Commander saw a white taxicab with five

GENERATING FRACTAL PATTERNS BY USING p-CIRCLE INVERSION

NASA Astrophysics Data System (ADS)

Ramírez, José L.; Rubiano, Gustavo N.; Zlobec, Borut Jurčič

2015-10-01

In this paper, we introduce the p-circle inversion which generalizes the classical inversion with respect to a circle (p = 2) and the taxicab inversion (p = 1). We study some basic properties and we also show the inversive images of some basic curves. We apply this new transformation to well-known fractals such as Sierpinski triangle, Koch curve, dragon curve, Fibonacci fractal, among others. Then we obtain new fractal patterns. Moreover, we generalize the method called circle inversion fractal be means of the p-circle inversion.

Correction of Measured Taxicab Exhaust Emission Data Based on Cmem Modle

NASA Astrophysics Data System (ADS)

Li, Q.; Jia, T.

2017-09-01

Carbon dioxide emissions from urban road traffic mainly come from automobile exhaust. However, the carbon dioxide emissions obtained by the instruments are unreliable due to time delay error. In order to improve the reliability of data, we propose a method to correct the measured vehicles' carbon dioxide emissions from instrument based on the CMEM model. Firstly, the synthetic time series of carbon dioxide emissions are simulated by CMEM model and GPS velocity data. Then, taking the simulation data as the control group, the time delay error of the measured carbon dioxide emissions can be estimated by the asynchronous correlation analysis, and the outliers can be automatically identified and corrected using the principle of DTW algorithm. Taking the taxi trajectory data of Wuhan as an example, the results show that (1) the correlation coefficient between the measured data and the control group data can be improved from 0.52 to 0.59 by mitigating the systematic time delay error. Furthermore, by adjusting the outliers which account for 4.73 % of the total data, the correlation coefficient can raise to 0.63, which suggests strong correlation. The construction of low carbon traffic has become the focus of the local government. In order to respond to the slogan of energy saving and emission reduction, the distribution of carbon emissions from motor vehicle exhaust emission was studied. So our corrected data can be used to make further air quality analysis.

Land mobile spectrum utilization: San Francisco, California and Chicago, Illinois

NASA Astrophysics Data System (ADS)

Reed, L. D.

1980-08-01

Radio frequency utilization by Federal Communication Commission licenses in the San Francisco and Chicago urbanized areas is described. The license include among others: police and fire departments; hospitals; public utilities; marine; and common carrier users. The extent of frequency utilization is described in terms of four occupancy categorizations (zero, low, substantial and very high). The rationale for these categories and their relationship to measured usage data is given. Summary tables enable direct comparison of the use by various individual, radio services, e.g., police, business, taxicab, etc. Separate analyses are given for utilization by each of the land mobile radio services and for each frequency band.

Awards to academic institutions by the Department of Transportation in FY 1975

DOE Office of Scientific and Technical Information (OSTI.GOV)

Megerian, G.K.; Whitfield, H.L.

1976-02-20

A comprehensive listing is given of contracts and grants awarded by the Department of Transportation to colleges and universities during fiscal year 1975. The awards are categorized into seven different schemes. Subject areas include (1) carpooling; (2) problems of the elderly and the handicapped; (3) energy; (4) environment; (5) facilities and services; (6) Federal Government role; (7) freight movement; (8) human factors; (9) land use planning; (10) management; (11) materials; (12) motorcycles; (13) noise; (14) personal rapid transit; (15) rural planning; (16) safety; (17) systems development; (18) taxicabs; (19) technology; (20) traffic control; (21) training; (22) tunneling; and (23) urbanmore » planning. (PMA)« less

Mass transit and appropriate technology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bell, L.

1978-06-01

Population pressures, dwinding fossil-fuel reserves, and new technological developments will make mass transet more and more competitive with private automobiles in the future. But future transit systems require a combination of high and low technologies--automated subways and conventional sidewalks. Buses and taxicabs may still be the answer in some cities, because more-sophisticated technologies may cause more problems than they solve. Larry Bell reviews information on some of the more advanced transit systems--those in service, proposed, and defunct. He concludes that the most appropriate thechnology for each problem will be found by aiming at balanced, integrated solutions that consider all responablemore » options. (MCW)« less

19 CFR 123.17 - Foreign repairs to domestic trucks, busses, taxicabs and their equipment.

Code of Federal Regulations, 2011 CFR

2011-04-01

... into another country, nor used in foreign local traffic otherwise than as an incident of their return to the United States. (b) Report of arrival and payment of duty on repairs. A report of the first... have been made in a foreign country, other than those required to restore such vehicle or equipment to...

19 CFR 123.17 - Foreign repairs to domestic trucks, busses, taxicabs and their equipment.

Code of Federal Regulations, 2010 CFR

2010-04-01

... into another country, nor used in foreign local traffic otherwise than as an incident of their return to the United States. (b) Report of arrival and payment of duty on repairs. A report of the first... have been made in a foreign country, other than those required to restore such vehicle or equipment to...

Potential markets for a satellite-based mobile communications system

NASA Technical Reports Server (NTRS)

Jamieson, W. M.; Peet, C. S.; Bengston, R. J.

1976-01-01

The objective of the study was to define the market needs for improved land mobile communications systems. Within the context of this objective, the following goals were set: (1) characterize the present mobile communications industry; (2) determine the market for an improved system for mobile communications; and (3) define the system requirements as seen from the potential customer's viewpoint. The scope of the study was defined by the following parameters: (1) markets were confined to U.S. and Canada; (2) range of operation generally exceeded 20 miles, but this was not restrictive; (3) the classes of potential users considered included all private sector users, and non-military public sector users; (4) the time span examined was 1975 to 1985; and (5) highly localized users were generally excluded - e.g., taxicabs, and local paging.

Barwood CNG Cab Fleet Study: Final Results

DOE Office of Scientific and Technical Information (OSTI.GOV)

Whalen, P.; Kelly, K.; John, M.

1999-05-03

This report describes a fleet study conducted over a 12-month period to evaluate the operation of dedicated compress natural gas (CNG) Ford Crown Victoria sedans in a taxicab fleet. In the study, we assess the performance and reliability of the vehicles and the cost of operating the CNG vehicles compared to gasoline vehicles. The study results reveal that the CNG vehicles operated by this fleet offer both economic and environmental advantages. The total operating costs of the CNG vehicles were about 25% lower than those of the gasoline vehicles. The CNG vehicles performed as well as the gasoline vehicles, andmore » were just as reliable. Barwood representatives and drivers have come to consider the CNG vehicles an asset to their business and to the air quality of the local community.« less

Pair correlation functions for identifying spatial correlation in discrete domains

NASA Astrophysics Data System (ADS)

Gavagnin, Enrico; Owen, Jennifer P.; Yates, Christian A.

2018-06-01

Identifying and quantifying spatial correlation are important aspects of studying the collective behavior of multiagent systems. Pair correlation functions (PCFs) are powerful statistical tools that can provide qualitative and quantitative information about correlation between pairs of agents. Despite the numerous PCFs defined for off-lattice domains, only a few recent studies have considered a PCF for discrete domains. Our work extends the study of spatial correlation in discrete domains by defining a new set of PCFs using two natural and intuitive definitions of distance for a square lattice: the taxicab and uniform metric. We show how these PCFs improve upon previous attempts and compare between the quantitative data acquired. We also extend our definitions of the PCF to other types of regular tessellation that have not been studied before, including hexagonal, triangular, and cuboidal. Finally, we provide a comprehensive PCF for any tessellation and metric, allowing investigation of spatial correlation in irregular lattices for which recognizing correlation is less intuitive.

Perception and reality of particulate matter exposure in New York City taxi drivers

PubMed Central

Gany, Francesca; Bari, Sehrish; Prasad, Lakshmi; Leng, Jennifer; Lee, Trevor; Thurston, George D; Gordon, Terry; Acharya, Sudha; Zelikoff, Judith T

2017-01-01

Background Exposure to fine particulate matter (PM2.5) and black carbon (BC) have been linked to negative health risks, but exposure among professional taxi drivers is unknown. This study measured drivers' knowledge, attitudes, and beliefs (KAB) about air pollution compared to direct measures of exposures. Methods Roadside and in-vehicle levels of PM2.5 and BC were continuously measured over a single shift and compared to central site monitoring. Participants completed an air pollution KAB questionnaire. Results Taxicab PM2.5 and BC concentrations were elevated compared to central monitoring. Average PM2.5 concentrations per 15-minute interval were 4 - 49 μg/m3; 1-minute peaks measured up to 452 μg/m3. BC levels were also elevated; reaching > 10 μg/m3. 56 of 100 drivers surveyed believed they were more exposed than non-drivers; 81 believed air pollution causes health problems. Conclusions Air pollution exposure among drivers likely exceeds EPA recommendations. Future studies should focus on reducing exposures and increasing awareness among taxi drivers. PMID:27168392

9th Diesel Engine Emissions Reduction (DEER) Workshop 2003

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kukla, P; Wright, J; Harris, G

2003-08-24

The PowerTrap{trademark} is a non-exhaust temperature dependent system that cannot become blocked and features a controlled regeneration process independent of the vehicle's drive cycle. The system has a low direct-current power source requirement available in both 12-volt and 24-volt configurations. The system is fully programmable, fully automated and includes Euro IV requirements of operation verification. The system has gained European component-type approval and has been tested with both on- road and off-road diesel fuel up to 2000 parts per million. The device is fail-safe: in the event of a device malfunction, it cannot affect the engine's performance. Accumulated mileage testingmore » is in excess of 640,000 miles to date. Vehicles include London-type taxicabs (Euro 1 and 2), emergency service fire engines (Euro 1, 2, and 3), inner city buses, and light-duty locomotives. Independent test results by Shell Global Solutions have consistently demonstrated 85-99 percent reduction of ultrafines across the 7-35 nanometer size range using a scanning mobility particle sizer with both ultra-low sulfur diesel and off-road high-sulfur fuel.« less

Road Traffic Anomaly Detection via Collaborative Path Inference from GPS Snippets

PubMed Central

Wang, Hongtao; Wen, Hui; Yi, Feng; Zhu, Hongsong; Sun, Limin

2017-01-01

Road traffic anomaly denotes a road segment that is anomalous in terms of traffic flow of vehicles. Detecting road traffic anomalies from GPS (Global Position System) snippets data is becoming critical in urban computing since they often suggest underlying events. However, the noisy and sparse nature of GPS snippets data have ushered multiple problems, which have prompted the detection of road traffic anomalies to be very challenging. To address these issues, we propose a two-stage solution which consists of two components: a Collaborative Path Inference (CPI) model and a Road Anomaly Test (RAT) model. CPI model performs path inference incorporating both static and dynamic features into a Conditional Random Field (CRF). Dynamic context features are learned collaboratively from large GPS snippets via a tensor decomposition technique. Then RAT calculates the anomalous degree for each road segment from the inferred fine-grained trajectories in given time intervals. We evaluated our method using a large scale real world dataset, which includes one-month GPS location data from more than eight thousand taxicabs in Beijing. The evaluation results show the advantages of our method beyond other baseline techniques. PMID:28282948

Dynamic Scheduling for Veterans Health Administration Patients using Geospatial Dynamic Overbooking.

PubMed

Adams, Stephen; Scherer, William T; White, K Preston; Payne, Jason; Hernandez, Oved; Gerber, Mathew S; Whitehead, N Peter

2017-10-12

The Veterans Health Administration (VHA) is plagued by abnormally high no-show and cancellation rates that reduce the productivity and efficiency of its medical outpatient clinics. We address this issue by developing a dynamic scheduling system that utilizes mobile computing via geo-location data to estimate the likelihood of a patient arriving on time for a scheduled appointment. These likelihoods are used to update the clinic's schedule in real time. When a patient's arrival probability falls below a given threshold, the patient's appointment is canceled. This appointment is immediately reassigned to another patient drawn from a pool of patients who are actively seeking an appointment. The replacement patients are prioritized using their arrival probability. Real-world data were not available for this study, so synthetic patient data were generated to test the feasibility of the design. The method for predicting the arrival probability was verified on a real set of taxicab data. This study demonstrates that dynamic scheduling using geo-location data can reduce the number of unused appointments with minimal risk of double booking resulting from incorrect predictions. We acknowledge that there could be privacy concerns with regards to government possession of one's location and offer strategies for alleviating these concerns in our conclusion.

Costs of occupational injury and illness across industries.

PubMed

Leigh, J Paul; Waehrer, Geetha; Miller, Ted R; Keenan, Craig

2004-06-01

This study has ranked industries using estimated total costs and costs per worker. This incidence study of nationwide data was carried out in 1993. The main outcome measure was total cost for medical care, lost productivity, and pain and suffering for the entire United States (US). The analysis was conducted using fatal and nonfatal injury and illness data recorded in large data sets from the US Bureau of Labor Statistics. Cost data were derived from workers' compensation records, estimates of lost wages, and jury awards. Current-value calculations were used to express all costs in 1993 in US dollars. The following industries were at the top of the list for average cost (cost per worker): taxicabs, bituminous coal and lignite mining, logging, crushed stone, oil field services, water transportation services, sand and gravel, and trucking. Industries high on the total-cost list were trucking, eating and drinking places, hospitals, grocery stores, nursing homes, motor vehicles, and department stores. Industries at the bottom of the cost-per-worker list included legal services, security brokers, mortgage bankers, security exchanges, and labor union offices. Detailed methodology was developed for ranking industries by total cost and cost per worker. Ranking by total costs provided information on total burden of hazards, and ranking by cost per worker provided information on risk. Industries that ranked high on both lists deserve increased research and regulatory attention.

On-demand high-capacity ride-sharing via dynamic trip-vehicle assignment.

PubMed

Alonso-Mora, Javier; Samaranayake, Samitha; Wallar, Alex; Frazzoli, Emilio; Rus, Daniela

2017-01-17

Ride-sharing services are transforming urban mobility by providing timely and convenient transportation to anybody, anywhere, and anytime. These services present enormous potential for positive societal impacts with respect to pollution, energy consumption, congestion, etc. Current mathematical models, however, do not fully address the potential of ride-sharing. Recently, a large-scale study highlighted some of the benefits of car pooling but was limited to static routes with two riders per vehicle (optimally) or three (with heuristics). We present a more general mathematical model for real-time high-capacity ride-sharing that (i) scales to large numbers of passengers and trips and (ii) dynamically generates optimal routes with respect to online demand and vehicle locations. The algorithm starts from a greedy assignment and improves it through a constrained optimization, quickly returning solutions of good quality and converging to the optimal assignment over time. We quantify experimentally the tradeoff between fleet size, capacity, waiting time, travel delay, and operational costs for low- to medium-capacity vehicles, such as taxis and van shuttles. The algorithm is validated with ∼3 million rides extracted from the New York City taxicab public dataset. Our experimental study considers ride-sharing with rider capacity of up to 10 simultaneous passengers per vehicle. The algorithm applies to fleets of autonomous vehicles and also incorporates rebalancing of idling vehicles to areas of high demand. This framework is general and can be used for many real-time multivehicle, multitask assignment problems.

Long-distance quantum communication over noisy networks without long-time quantum memory

NASA Astrophysics Data System (ADS)

Mazurek, Paweł; Grudka, Andrzej; Horodecki, Michał; Horodecki, Paweł; Łodyga, Justyna; Pankowski, Łukasz; PrzysieŻna, Anna

2014-12-01

The problem of sharing entanglement over large distances is crucial for implementations of quantum cryptography. A possible scheme for long-distance entanglement sharing and quantum communication exploits networks whose nodes share Einstein-Podolsky-Rosen (EPR) pairs. In Perseguers et al. [Phys. Rev. A 78, 062324 (2008), 10.1103/PhysRevA.78.062324] the authors put forward an important isomorphism between storing quantum information in a dimension D and transmission of quantum information in a D +1 -dimensional network. We show that it is possible to obtain long-distance entanglement in a noisy two-dimensional (2D) network, even when taking into account that encoding and decoding of a state is exposed to an error. For 3D networks we propose a simple encoding and decoding scheme based solely on syndrome measurements on 2D Kitaev topological quantum memory. Our procedure constitutes an alternative scheme of state injection that can be used for universal quantum computation on 2D Kitaev code. It is shown that the encoding scheme is equivalent to teleporting the state, from a specific node into a whole two-dimensional network, through some virtual EPR pair existing within the rest of network qubits. We present an analytic lower bound on fidelity of the encoding and decoding procedure, using as our main tool a modified metric on space-time lattice, deviating from a taxicab metric at the first and the last time slices.

On-demand high-capacity ride-sharing via dynamic trip-vehicle assignment

PubMed Central

Alonso-Mora, Javier; Samaranayake, Samitha; Wallar, Alex; Frazzoli, Emilio; Rus, Daniela

2017-01-01

Ride-sharing services are transforming urban mobility by providing timely and convenient transportation to anybody, anywhere, and anytime. These services present enormous potential for positive societal impacts with respect to pollution, energy consumption, congestion, etc. Current mathematical models, however, do not fully address the potential of ride-sharing. Recently, a large-scale study highlighted some of the benefits of car pooling but was limited to static routes with two riders per vehicle (optimally) or three (with heuristics). We present a more general mathematical model for real-time high-capacity ride-sharing that (i) scales to large numbers of passengers and trips and (ii) dynamically generates optimal routes with respect to online demand and vehicle locations. The algorithm starts from a greedy assignment and improves it through a constrained optimization, quickly returning solutions of good quality and converging to the optimal assignment over time. We quantify experimentally the tradeoff between fleet size, capacity, waiting time, travel delay, and operational costs for low- to medium-capacity vehicles, such as taxis and van shuttles. The algorithm is validated with ∼3 million rides extracted from the New York City taxicab public dataset. Our experimental study considers ride-sharing with rider capacity of up to 10 simultaneous passengers per vehicle. The algorithm applies to fleets of autonomous vehicles and also incorporates rebalancing of idling vehicles to areas of high demand. This framework is general and can be used for many real-time multivehicle, multitask assignment problems. PMID:28049820

Occupational and personal factors associated with acquired lumbar spondylolisthesis of urban taxi drivers

PubMed Central

Chen, J; Chan, W; Katz, J; Chang, W; Christiani, D

2004-01-01

Aims: To investigate the occupational and personal factors associated with lumbar spondylolisthesis in taxi drivers. Methods: Cross-sectional analysis of the baseline data from the Taxi Drivers' Health Study cohort. Information was retrieved from the medical records of standardised lumbosacral spine plain films, age, and anthropometric measures of 1242 subjects. Acquired spondylolisthesis (ASL) was defined as non-lytic spondylolisthesis involving lumbar spines above L5. Questionnaires were used to gather information on demographic features, health behaviours, exercise, work related physical and psychosocial factors, and driving time profiles. Multiple logistic regression was used to model the odds ratio (OR) for prevalent ASL cases associated with personal and occupational factors. Results: A total of 40 cases (3.2%) of ASL were diagnosed. Among those driving ⩽5 years, 6–15 years, and >15 years, the estimated prevalence of lumbar spondylolisthesis was 1.1%, 2.4%, and 7.1% respectively. Results of multiple logistic regression suggested that taxicab driving >15 years (OR = 3.4, 95% CI 1.1 to 10.7, compared to driving ⩽5 years), age (OR = 2.6, 95% CI 1.1 to 6.6 for age 46–55; and OR = 4.8, 95% CI 1.8 to 12.9 for age >55), body mass index ⩾25 kg/m2 (OR = 2.2, 95% CI 1.1 to 4.6), and frequent strenuous exercise (OR = 2.2, 95% CI 1.1 to 4.5) were significantly associated with higher prevalence of spondylolisthesis. There was a consistent likely exposure-response relation between professional seniority and ASL prevalence. Conclusions: Longitudinal studies are needed to confirm the observed association between professional driving and spondylolisthesis, and to examine further the specific occupational exposures accountable for this association. PMID:15550605

Understanding the brain through its spatial structure

NASA Astrophysics Data System (ADS)

Morrison, Will Zachary

The spatial location of cells in neural tissue can be easily extracted from many imaging modalities, but the information contained in spatial relationships between cells is seldom utilized. This is because of a lack of recognition of the importance of spatial relationships to some aspects of brain function, and the reflection in spatial statistics of other types of information. The mathematical tools necessary to describe spatial relationships are also unknown to many neuroscientists, and biologists in general. We analyze two cases, and show that spatial relationships can be used to understand the role of a particular type of cell, the astrocyte, in Alzheimer's disease, and that the geometry of axons in the brain's white matter sheds light on the process of establishing connectivity between areas of the brain. Astrocytes provide nutrients for neuronal metabolism, and regulate the chemical environment of the brain, activities that require manipulation of spatial distributions (of neurotransmitters, for example). We first show, through the use of a correlation function, that inter-astrocyte forces determine the size of independent regulatory domains in the cortex. By examining the spatial distribution of astrocytes in a mouse model of Alzheimer's Disease, we determine that astrocytes are not actively transported to fight the disease, as was previously thought. The paths axons take through the white matter determine which parts of the brain are connected, and how quickly signals are transmitted. The rules that determine these paths (i.e. shortest distance) are currently unknown. By measurement of axon orientation distributions using three-point correlation functions and the statistics of axon turning and branching, we reveal that axons are restricted to growth in three directions, like a taxicab traversing city blocks, albeit in three-dimensions. We show how geometric restrictions at the small scale are related to large-scale trajectories. Finally we discuss the

The collaborative image of the city: mapping the inequality of urban perception.

PubMed

Salesses, Philip; Schechtner, Katja; Hidalgo, César A

2013-01-01

A traveler visiting Rio, Manila or Caracas does not need a report to learn that these cities are unequal; she can see it directly from the taxicab window. This is because in most cities inequality is conspicuous, but also, because cities express different forms of inequality that are evident to casual observers. Cities are highly heterogeneous and often unequal with respect to the income of their residents, but also with respect to the cleanliness of their neighborhoods, the beauty of their architecture, and the liveliness of their streets, among many other evaluative dimensions. Until now, however, our ability to understand the effect of a city's built environment on social and economic outcomes has been limited by the lack of quantitative data on urban perception. Here, we build on the intuition that inequality is partly conspicuous to create quantitative measure of a city's contrasts. Using thousands of geo-tagged images, we measure the perception of safety, class and uniqueness; in the cities of Boston and New York in the United States, and Linz and Salzburg in Austria, finding that the range of perceptions elicited by the images of New York and Boston is larger than the range of perceptions elicited by images from Linz and Salzburg. We interpret this as evidence that the cityscapes of Boston and New York are more contrasting, or unequal, than those of Linz and Salzburg. Finally, we validate our measures by exploring the connection between them and homicides, finding a significant correlation between the perceptions of safety and class and the number of homicides in a NYC zip code, after controlling for the effects of income, population, area and age. Our results show that online images can be used to create reproducible quantitative measures of urban perception and characterize the inequality of different cities.

The Collaborative Image of The City: Mapping the Inequality of Urban Perception

PubMed Central

Salesses, Philip; Schechtner, Katja; Hidalgo, César A.

2013-01-01

A traveler visiting Rio, Manila or Caracas does not need a report to learn that these cities are unequal; she can see it directly from the taxicab window. This is because in most cities inequality is conspicuous, but also, because cities express different forms of inequality that are evident to casual observers. Cities are highly heterogeneous and often unequal with respect to the income of their residents, but also with respect to the cleanliness of their neighborhoods, the beauty of their architecture, and the liveliness of their streets, among many other evaluative dimensions. Until now, however, our ability to understand the effect of a city's built environment on social and economic outcomes has been limited by the lack of quantitative data on urban perception. Here, we build on the intuition that inequality is partly conspicuous to create quantitative measure of a city's contrasts. Using thousands of geo-tagged images, we measure the perception of safety, class and uniqueness; in the cities of Boston and New York in the United States, and Linz and Salzburg in Austria, finding that the range of perceptions elicited by the images of New York and Boston is larger than the range of perceptions elicited by images from Linz and Salzburg. We interpret this as evidence that the cityscapes of Boston and New York are more contrasting, or unequal, than those of Linz and Salzburg. Finally, we validate our measures by exploring the connection between them and homicides, finding a significant correlation between the perceptions of safety and class and the number of homicides in a NYC zip code, after controlling for the effects of income, population, area and age. Our results show that online images can be used to create reproducible quantitative measures of urban perception and characterize the inequality of different cities. PMID:23894301

Essays in Applied Microeconomics

NASA Astrophysics Data System (ADS)

Ge, Qi

This dissertation consists of three self-contained applied microeconomics essays on topics related to behavioral economics and industrial organization. Chapter 1 studies how sentiment as a result of sports event outcomes affects consumers' tipping behavior in the presence of social norms. I formulate a model of tipping behavior that captures consumer sentiment following a reference-dependent preference framework and empirically test its relevance using the game outcomes of the NBA and the trip and tipping data on New York City taxicabs. While I find that consumers' tipping behavior responds to unexpected wins and losses of their home team, particularly in close game outcomes, I do not find evidence for loss aversion. Coupled with the findings on default tipping, my empirical results on the asymmetric tipping responses suggest that while social norms may dominate loss aversion, affect and surprises can result in freedom on the upside of tipping. Chapter 2 utilizes a novel data source of airline entry and exit announcements and examines how the incumbent airlines adjust quality provisions as a response to their competitors' announcements and the role of timing in such responses. I find no evidence that the incumbents engage in preemptive actions when facing probable entry and exit threats as signaled by the competitors' announcements in either short term or long term. There is, however, evidence supporting their responses to the competitors' realized entry or exit. My empirical findings underscore the role of timing in determining preemptive actions and suggest that previous studies may have overestimated how the incumbent airlines respond to entry threats. Chapter 3, which is collaborated with Benjamin Ho, investigates the habit formation of consumers' thermostat setting behavior, an often implicitly made decision and yet a key determinant of home energy consumption and expenditures. We utilize a high frequency dataset on household thermostat usage and find that

Intersection delay estimation from floating car data via principal curves: a case study on Beijing's road network

NASA Astrophysics Data System (ADS)

Liu, Xiliang; Lu, Feng; Zhang, Hengcai; Qiu, Peiyuan

2013-06-01

It is a pressing task to estimate the real-time travel time on road networks reliably in big cities, even though floating car data has been widely used to reflect the real traffic. Currently floating car data are mainly used to estimate the real-time traffic conditions on road segments, and has done little for turn delay estimation. However, turn delays on road intersections contribute significantly to the overall travel time on road networks in modern cities. In this paper, we present a technical framework to calculate the turn delays on road networks with float car data. First, the original floating car data collected with GPS equipped taxies was cleaned and matched to a street map with a distributed system based on Hadoop and MongoDB. Secondly, the refined trajectory data set was distributed among 96 time intervals (from 0: 00 to 23: 59). All of the intersections where the trajectories passed were connected with the trajectory segments, and constituted an experiment sample, while the intersections on arterial streets were specially selected to form another experiment sample. Thirdly, a principal curve-based algorithm was presented to estimate the turn delays at the given intersections. The algorithm argued is not only statistically fitted the real traffic conditions, but also is insensitive to data sparseness and missing data problems, which currently are almost inevitable with the widely used floating car data collecting technology. We adopted the floating car data collected from March to June in Beijing city in 2011, which contains more than 2.6 million trajectories generated from about 20000 GPS-equipped taxicabs and accounts for about 600 GB in data volume. The result shows the principal curve based algorithm we presented takes precedence over traditional methods, such as mean and median based approaches, and holds a higher estimation accuracy (about 10%-15% higher in RMSE), as well as reflecting the changing trend of traffic congestion. With the estimation

Incentives for increasing prenatal care use by women in order to improve maternal and neonatal outcomes.

PubMed

Till, Sara R; Everetts, David; Haas, David M

2015-12-15

Prenatal care is recommended during pregnancy as a method to improve neonatal and maternal outcomes. Improving the use of prenatal care is important, particularly for women at moderate to high risk of adverse outcomes. Incentives are sometimes utilized to encourage women to attend prenatal care visits. To determine whether incentives are an effective tool to increase utilization of timely prenatal care among women. We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 January 2015) and the reference lists of all retrieved studies. Randomized controlled trials (RCTs), quasi-RCTs, and cluster-RCTs that utilized direct incentives to pregnant women explicitly linked to initiation and frequency of prenatal care were included. Incentives could include cash, vouchers, coupons or products not generally offered to women as a standard of prenatal care. Comparisons were to no incentives and to incentives not linked directly to utilization of care. We also planned to compare different types of interventions, i.e. monetary versus products or services. Two review authors independently assessed studies for inclusion and methodological quality. Two review authors independently extracted data. Data were checked for accuracy. We identified 11 studies (19 reports), six of which we excluded. Five studies, involving 11,935 pregnancies were included, but only 1893 pregnancies contributed data regarding our specified outcomes. Incentives in the studies included cash, gift card, baby carrier, baby blanket or taxicab voucher and were compared with no incentives. Meta-analysis was performed for only one outcome 'Return for postpartum care' and this outcome was not pre-specified in our protocol. Other analyses were restricted to data from single studies.Trials were at a moderate risk of bias overall. Randomization and allocation were adequate and risk of selection bias was low in three studies and unclear in two studies. None of the studies were blinded to the