African entrepreneurs: An analysis of their motivation for starting their own business

This study analyses the motivation of entrepreneurs for starting a business.  More specifically, it aims to identify whether entrepreneurs have common  motives for starting their own business, and whether men and women have  different reasons for becoming entrepreneurs. A motivation scale and openended  questions were used to measure motivation on a sample of more than 100  entrepreneurs. The results of a factor analysis indicate that entrepreneurs have  various reasons for starting a business, and are primarily motivated by the needs  for independence, material incentives and achievement

Digital dual-rate burst-mode receiver for 10G and 1G coexistence in optical access networks

A digital dual-rate burst-mode receiver, intended to support 10 and 1 Gb/s coexistence in optical access networks, is proposed and experimentally characterized. The receiver employs a standard DC-coupled photoreceiver followed by a 20 GS/s digitizer and the detection of the packet presence and line-rate is implemented in the digital domain. A polyphase, 2 samples-per-bit digital signal processing algorithm is then used for efficient clock and data recovery of the 10/1.25 Gb/s packets. The receiver performance is characterized in terms of sensitivity and dynamic range under burst-mode operation for 10/1.25 Gb/s intensity modulated data in terms of both the packet error rate (PER) and the payload bit error rate (pBER). The impact of packet preamble lengths of 16, 32, 48, and 64 bits, at 10 Gb/s, on the receiver performance is investigated. We show that there is a trade-off between pBER and PER that is limited by electrical noise and digitizer clipping at low and high received powers, respectively, and that a 16/2-bit preamble at 10/1.25 Gb/s is sufficient to reliably detect packets at both line-rates over a burst-to-burst dynamic range of 14,5dB with a sensitivity of -18.5dBm at 10 Gb/s. (C)2011 Optical Society of Americ

Clinical effectiveness of a rehabilitation program integrating exercise, self-management, and active coping strategies for chronic knee pain: a cluster randomized trial.

OBJECTIVE: Chronic knee pain is a major cause of disability and health care expenditure, but there are concerns about efficacy, cost, and side effects associated with usual primary care. Conservative rehabilitation may offer a safe, effective, affordable alternative. We compared the effectiveness of a rehabilitation program integrating exercise, self-management, and active coping strategies (Enabling Self-management and Coping with Arthritic Knee Pain through Exercise [ESCAPE-knee pain]) with usual primary care in improving functioning in persons with chronic knee pain. METHODS: We conducted a single-blind, pragmatic, cluster randomized controlled trial. Participants age >/=50 years, reporting knee pain for >6 months, were recruited from 54 inner-city primary care practices. Primary care practices were randomized to continued usual primary care (i.e., whatever intervention a participant's primary care physician deemed appropriate), usual primary care plus the rehabilitation program delivered to individual participants, or usual primary care plus the rehabilitation program delivered to groups of 8 participants. The primary outcome was self-reported functioning (Western Ontario and McMaster Universities Osteoarthritis Index physical functioning [WOMAC-func]) 6 months after completing rehabilitation. RESULTS: A total of 418 participants were recruited; 76 (18%) withdrew, only 5 (1%) due to adverse events. Rehabilitated participants had better functioning than participants continuing usual primary care (-3.33 difference in WOMAC-func score; 95% confidence interval [95% CI] -5.88, -0.78; P = 0.01). Improvements were similar whether participants received individual rehabilitation (-3.53; 95% CI -6.52, -0.55) or group rehabilitation (-3.16; 95% CI -6.55, -0.12). CONCLUSION: ESCAPE-knee pain provides a safe, relatively brief intervention for chronic knee pain that is equally effective whether delivered to individuals or groups of participants

Existential Types for Relaxed Noninterference

Information-flow security type systems ensure confidentiality by enforcing noninterference: a program cannot leak private data to public channels. However, in practice, programs need to selectively declassify information about private data. Several approaches have provided a notion of relaxed noninterference supporting selective and expressive declassification while retaining a formal security property. The labels-as-functions approach provides relaxed noninterference by means of declassification policies expressed as functions. The labels-as-types approach expresses declassification policies using type abstraction and faceted types, a pair of types representing the secret and public facets of values. The original proposal of labels-as-types is formulated in an object-oriented setting where type abstraction is realized by subtyping. The object-oriented approach however suffers from limitations due to its receiver-centric paradigm. In this work, we consider an alternative approach to labels-as-types, applicable in non-object-oriented languages, which allows us to express advanced declassification policies, such as extrinsic policies, based on a different form of type abstraction: existential types. An existential type exposes abstract types and operations on these; we leverage this abstraction mechanism to express secrets that can be declassified using the provided operations. We formalize the approach in a core functional calculus with existential types, define existential relaxed noninterference, and prove that well-typed programs satisfy this form of type-based relaxed noninterference

A Cultural Immersion Experience to Enhance Nursing Students’ Appreciation and Understanding of Different Cultures

The practice of studying abroad for professional development is not new and has been undertaken by scholars since the medieval times, however it is a relatively new endeavor in nursing education. Research has shown that cultural knowledge in nursing is extremely important and the lack of it may cause deficits in practice. The purpose of this study is a two-fold. Nursing faculty completed a literature review and sent out a self-designed 15-question survey to all nursing students registered for the travel abroad experience. This experience took place during March 14-24, 2019. The goal of this experience was professional growth and to be more culturally aware in various populations

Super-resolving phase measurements with a multi-photon entangled state

Using a linear optical elements and post-selection, we construct an entangled polarization state of three photons in the same spatial mode. This state is analogous to a ``photon-number path entangled state'' and can be used for super-resolving interferometry. Measuring a birefringent phase shift, we demonstrate two- and three-fold improvements in phase resolution.Comment: 4 pages, 3 figure

Spectrally Efficient WDM Nyquist Pulse-Shaped Subcarrier Modulation Using a Dual-Drive Mach-Zehnder Modulator and Direct Detection

High data transmission capacity is increasingly needed in shortand medium-haul optical communication links. Cost-effective wavelength division multiplexed (WDM) transceiver architectures, achieving high information spectral densities (ISDs) (>1 b/s/Hz) and using low-complexity direct detection receivers are attractive solutions for such links. In this paper, we assess the use of dual-drive Mach-Zehnder modulators (DD-MZMs), and compare them with in-phase quadrature (IQ)-modulators for generating spectrally-efficient single sideband Nyquist pulse-shaped 16-QAM subcarrier (N-SCM) modulation format signals. The impact of the extinction ratio (ER) of a modulator on the optical sideband suppression ratio (OSSR) was investigated for the SSB signals in WDM systems, together with the resulting impact on inter-channel crosstalk penalties. First, in back-to-back operation, an IQ-modulator with an ER of 30 dB and a DD-MZM with an ER of 18 dB were experimentally compared in a 6×25 Gb/s WDM system by varying the channel spacing. Following this comparison, 16 GHz-spaced 6×25 Gb/s WDM signal transmission was experimentally demonstrated using the DD-MZM. The experiment was performed using a recirculating loop with uncompensated standard single-mode fiber (SSMF) and EDFA-only amplification. The maximum achievable transmission distances for single channel and WDM signals were found to be 565 and 242 km, respectively, at a net optical ISD of 1.5 b/s/Hz. This is the first experimental comparison of such modulator types for SSB N-SCM signal generation and the highest achieved ISD using a DD-MZM in direct-detection WDM transmission

Demonstration of a 10 Gbit/s Long Reach Wavelength Converting Optical Access Network

This paper demonstrates a 10 Gbit/s wavelength converting access network utilising a centralised optical processing unit that consolidates multiple low cost PONs onto a DWDM backhaul. The centralised processing unit functions as an amplifier, wavelength converter, pre-chirping stage and optical burst equaliser to map legacy PONs onto a DWDM grid for efficient backhaul transmission and to ease the dynamic range requirement of the 10 Gbit/s burst-mode receiver at the optical line termination (OLT). The dispersion limited performance, wavelength tolerance, and burst-mode dynamic range are evaluated demonstrating a maximum range of 62 km for 20 nm of input wavelength variation and a dynamic range of up to 22 dB

Performance of an optical equalizer in a 10 G wavelength converting optical access network

A centralized optical processing unit (COPU) that functions both as a wavelength converter (WC) and optical burst equaliser in a 10 Gb/s wavelength-converting optical access network is proposed and experimentally characterized. This COPU is designed to consolidate drifting wavelengths generated with an uncooled laser in the upstream direction into a stable wavelength channel for WDM backhaul transmission and to equalize the optical loud/soft burst power in order to relax the burst-mode receiver dynamic range requirement. The COPU consists of an optical power equaliser composed of two cascaded SOAs followed by a WC. Using an optical packet generator and a DC-coupled PIN-based digital burst-mode receiver, the COPU is characterized in terms of payload-BER for back-to-back and backhaul transmission distances of 22, 40, and 62 km. We show that there is a compromise between the receiver sensitivity and overload points that can be optimized tuning the WC operating point for a particular backhaul fiber transmission distance. Using the optimized settings, sensitivities of −30.94, −30.17, and −27.26 dBm with overloads of −9.3, −5, and >-5 dBm were demonstrated for backhaul transmission distances of 22, 40 and 62 km, respectively