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The interurban network of criminal collaboration in Canada is described, and possible explanations for its structure are explored. The data include all police-reported co-offences in the 32 major cities of Canada during 2006–09. Component analysis and graph drawings in network space and in geospace elucidate the structure of the network. Quadratic assignment procedure multiple regressions, repeated separately on the networks of instrumental and noninstrumental co-offences, test hypotheses about possible determinants of the network structure. The cities form one connected component, containing two clusters connected by a link between Toronto and Vancouver. One cluster, centred on the triad of Toronto, Montreal, and Ottawa, comprises the cities in Ontario and Quebec, with weak links to cities in the Atlantic provinces. The other cluster, centred on Vancouver, comprises the cities in the four western provinces. The structure is strongly correlated with the residential mobility of the general population, which in turn is strongly correlated with intercity distances. The correlation with mobility is less strong for instrumental than for noninstrumental crimes. The structure of this co-offending network can be explained by criminals’ routine activities, namely ordinary residential mobility, but the alternative explanation of purposive interurban criminal collaboration is more plausible for instrumental crime.

ULTRARAM™ is a non-volatile memory with the potential to achieve fast, ultra-low-energy electron storage in a floating gate accessed through a triple-barrier resonant tunnelling heterostructure. Here we report the implementation of ULTRARAM™ on a Si substrate; a vital step towards cost-effective mass production. Sample growth was carried out using molecular beam epitaxy, by first depositing an AlSb nucleation layer to seed the growth of a GaSb buffer layer, followed by the III-V memory epilayers. Fabricated single-cell memories show clear 0/1 logic-state contrast after ≤10-ms duration program/erase pulses of ~2.5 V, a remarkably fast switching speed for 10- and 20-µm devices. Furthermore, the combination of low voltage and small device capacitance per unit area results in a switching energy that is orders of magnitude lower than dynamic random access memory and flash, for a given cell size. Extended testing of the devices revealed retention in excess of 1000 years and degradation-free endurance of over 107 program/erase cycles, exceeding very recent results for similar devices on GaAs substrates.

Thermophotovoltaic (TPV) devices based on GaInAsSb lattice matched to GaSb (100) substrates have demonstrated high external quantum efficiencies (EQEs) in the mid-infrared spectral range, making them promising candidates for waste heat recovery from high temperature “blackbody” sources. In this work, the GaInAsSb alloy has been integrated onto more cost-effective GaAs (100) substrates by using advanced metamorphic buffer layer techniques in molecular beam epitaxy (MBE), which included an interfacial misfit (IMF) array at the GaSb/GaAs interface followed by GaInSb/GaSb dislocation filtering layers. The threading dislocations in the GaInAsSb region can be efficiently supressed, resulting in high quality materials for TPV applications. To determine the performance of the GaInAsSb TPV on GaAs it was compared with a cell grown lattice matched onto GaSb substrate having the same structure. The resulting TPV on GaAs exhibited similar dark current-voltage characteristics with that on GaSb. Under illumination from an 800 °C silicon nitride emitter, the short circuit current density (Jsc) from the GaInAsSb TPVs on GaAs reached more than 90% of the control cell on GaSb, and the open circuit voltage (Voc) exceeded 80% of the cell on GaSb. The EQE from the TPV on GaAs reached around 62%, the highest value reported from this type of TPV on GaAs. With improved TPV structure design, large area GaInAsSb TPV panels on GaAs substrates can be realized in the future for waste heat energy recovery applications.

Silicon photonics has emerged as the most promising technology for next-generation compact optoelectronic systems, but further development is still required to achieve efficient and reliable on-chip light sources. Direct epitaxial growth of antimonide-based compound semiconductor materials on silicon provides a pathway toward the monolithic integration of new, mid-infrared solid-state light sources and comprehensive photonic circuits on silicon platforms. Such devices have wide-ranging applications in environmental monitoring and medical diagnostics. This paper reports on the realization of a mid-infrared InAsSb light emitting diode directly integrated onto silicon using molecular beam epitaxy. The heteroepitaxial integration of the InAsSb p-i-n device onto silicon was achieved with the use of a novel, antiphase domain-free, GaSb-on-silicon buffer layer. The device exhibited efficient light emission at room temperature, peaking at around 4.5 μm, which corresponds well to the CO2 atmospheric absorption band. An output power of 6 μW and an external quantum efficiency of 0.011% was measured at 300 K. These results demonstrate mid-infrared III-V light emitting diodes can be directly grown on silicon, which is an essential step towards the realization of the next generation, on-chip integrated light sources.

GaSb-based materials can be used to produce high performance photonic devices operating in the technologically important mid-infrared spectral range. Direct epitaxial growth of GaSb on silicon (Si) is an attractive method to reduce manufacturing costs and opens the possibility of new applications, such as lab-on-a-chip MIR photonic integrated circuits and monolithic integration of focal plane arrays (FPAs) with Si readout integrated circuits (ROICs). However, fundamental material dissimilarities, such as the large lattice mismatch, polar-nonpolar character of the III-V/Si interface and differences in thermal expansion coefficients lead to the formation of threading dislocations and antiphase domains, which effect the device performance. This work reports on the molecular beam epitaxial growth of high quality GaSb-based materials and devices onto Si. This was achieved using a novel growth procedure consisting of an efficient AlSb interfacial misfit array, a two-step GaSb growth temperature procedure and a series of dislocation filter superlattices, resulting in a low defect density, anti-phase domain free GaSb buffer layer on Si. A nBn barrier photodetector based on a type-II InAs/InAsSb superlattice was grown on top of the buffer layer. The device exhibited an extended 50 % cut-off wavelength at 5.40 μm at 200 K which moved to 5.9 μm at 300 K. A specific detectivity of 1.5 x1010 Jones was measured, corresponding in an external quantum efficiency of 25.6 % at 200 K.

There are many applications for light-emitting diodes (LEDs) that can operate in the mid-infrared spectral range. However, the efficiency of these devices at room temperature is limited by competing nonradiative recombination mechanisms, inadequate carrier confinement, and insufficient optical extraction. Earlier devices based on bulk materials and heterojunctions have been quite successful to date, leading to some commercialization, but several new designs containing quantum structures for the active region have since been proposed and are being studied. Similarly, there is growing interest in using more cost-effective substrates requiring the development of metamorphic buffer layers as well as resonant cavity structures to increase optical extraction. An overview of the current status of mid-infrared LED technology is given here together with a brief summary of some recent developments.

InAs thermophotovoltaic (TPV) cells with external quantum efficiency at the peak wavelengths reaching 71% at low temperature and 55% at room temperature are reported, which are the highest values to date for InAs. The TPV exhibited 10% power conversion efficiency at 100 K cell temperature. The dark and light current-voltage characteristics were measured at different cell temperatures (100–340 K) in response to heat sources in the range 500–800 °C. The resulting dependences of the output voltage and current as well as the spectral response of the InAs TPV have been extensively characterized for waste heat recovery applications. The performance of these cells is strongly determined by the dark current which increases rapidly with increasing cell temperature originating from bandgap narrowing, which resulted in a reduction of open circuit voltage and output power.

Most MPA networks are designed only with ecological processes in mind to increase their conservation utility. However, since MPA networks often involve large geographic areas, they also affect and involve multiple actors, institutions, and policy sectors. A key challenge when establishing an effective MPA network is to align the ‘social system’ with the biophysical MPA network (the ‘ecological system’). This challenge is often denoted as ‘social–ecological fit’. Facilitating collaborative social interactions among various actors and stakeholders (social connectivity) is equally as important as accomplishing ecological connectivity. New analytical approaches are required to effectively examine this ‘social’ dimension of fit. An emerging marine reserve network in Jamaica and the recent invasion of Indo-Pacific lionfish are used as a case study to: (1) examine the extent to which horizontal and vertical social ties bring local and national actors together to collaborate, coordinate, and share knowledge; and (2) assess the extent to which different attributes and features of such multilevel social networks may enhance or inhibit particular aspects of social–ecological fit. Findings suggest that multilevel linkages have played the greatest role in relation to enhancing fit in the marine reserve network in the context of the recent lionfish invasion. However, the long-term propensity of the multi-actor and multilevel networks to enhance social–ecological fit is uncertain given the prevalence of weak social ties, lack of a culture of information sharing and collaboration, and limited financial resources.

We report on the first single-junction GaSb solar cell epitaxially grown on a Si substrate. A control stand-alone GaSb solar cell was primarily fabricated, which demonstrated a 5.90% efficiency (AM1.5G). The preparation, growth and manufacturing procedures were then adapted to create the GaSb-on-Si solar cell. The hybrid device resulted in a degraded efficiency for which comparison between experimental and simulated data revealed dominant non-radiative recombination processes. Material and electrical characterization also highlighted the impact of anti-phase domains and boundaries and threading dislocation density on the shunt resistance of the cell. Nevertheless, the GaSb-on-Si cell performance is close to recent results on the integration of GaSb solar cells on GaAs, despite a much larger lattice mismatch (12% vs 8%). Routes for improvement, concerning the material quality and cell structure, are proposed. This work lays the foundations of a GaSb-based multi-junction solar cell monolithically integrated on Si.

Mid-infrared (MIR) silicon photonics holds the potential for realizing next generation ultracompact spectroscopic systems for applications in gas sensing, defense, and medical diagnostics. The direct epitaxial growth of antimonide-based compound semiconductors on silicon provides a promising approach for extending the wavelength of silicon photonics to the longer infrared range. This paper reports on the fabrication of a high performance MIR photodetector directly grown onto silicon by molecular beam epitaxy. The device exhibited an extended cutoff wavelength at ∼5.5 μm and a dark current density of 1.4 × 10–2 A/cm2 under 100 mV reverse bias at 200 K. A responsivity of 0.88 A/W and a specific detectivity in the order of 1.5 × 1010 Jones was measured at 200 K under 100 mV reverse bias operation. These results were achieved through the development of an innovative structure which incorporates a type-II InAs/InAsSb superlattice-based barrier nBn photodetector grown on a GaSb-on-silicon buffer layer. The difficulties in growing GaSb directly on silicon were overcome using a novel growth procedure consisting of an efficient AlSb interfacial misfit array, a two-step growth temperature procedure and dislocation filters resulting in a low defect density, antiphase domain free GaSb epitaxial layer on silicon. This work demonstrates that complex superlattice-based MIR photodetectors can be directly integrated onto a Si platform, which provides a pathway toward the realization of new, high performance, large area focal plane arrays and mid-infrared integrated photonic circuits.

The capture cross-section, intersubband optical cross-section and non-radiative emission rates related to localized hole states are obtained for p-i-n solar cells containing GaSb/GaAs quantum rings embedded within the i-region of the device. The technique developed uses the intraband photoemission current to probe the charge state of the nanostructures during two-color excitation. Analysis of the excitation power dependence revealed a non-radiative hole capture lifetime of 12 ns under low excitation conditions, with high injection leading to the saturation of the hole occupancy within the quantum-rings. The decay characteristics of the optical hole emission current has also been exploited to determine the spectral and temperature dependence of the radiative and non-radiative hole escape mechanisms from the quantum-rings.

The qHAADF method allows the quantification of the composition at atomic column resolution in semiconductor materials by comparing the HAADF-STEM intensities between a region of interest to a region of the material of known composition. However, the application of this qHAADF approach requires both regions to be differentiable and included in the same micrograph at close proximity. This limits the application of this approach to certain materials and magnifications where this requirement is fulfilled. In this work, we extend the qHAADF method to analyses where the reference region is imaged in a separate micrograph. The validity of this modified method is proved by comparison to the original qHAADF approach using HAADF-STEM simulated images of the semiconductor heterostructure InSb/InAs. Additionally, the methods are applied successfully to experimental images both of a simple InSb/InAs interface and of a complex InSb/GaSb heterostructure, justifying the significance of the modified method over the original method.

Background The success of treatment for substance use issues varies with personal and social factors, including the composition and structure of the individual's personal support network. This paper describes the personal support networks and social capital of a sample of Italian adults after long-term residential therapeutic treatment for substance use issues, and analyses network correlates of post-treatment substance use (relapse). Methods Using a social network analysis approach, data were obtained from structured interviews (90–120min long) with 80 former clients of a large non-governmental therapeutic treatment agency in Italy providing voluntary residential treatments and rehabilitation services for substance use issues. Participants had concluded the program at least six months prior. Data were collected on socio-demographic variables, addiction history, current drug use status (drug-free or relapsed), and the composition and structure of personal support networks. Factors related to risk of relapse were assessed using bivariate and multivariate logistic regression models. Results A main goal of this study was to identify differences between the support network profiles of drug free and relapsed participants. Drug free participants had larger, less dense, more heterogeneous and reciprocal support networks, and more brokerage social capital than relapsed participants. Additionally, a lower risk of relapse was associated with higher socio-economic status, being married/cohabiting, and having network members with higher socio-economic status, who have greater occupational heterogeneity, and reciprocate support. Conclusions Post-treatment relapse was found to be negatively associated with the socioeconomic status and occupational heterogeneity of ego's support network, reciprocity in the ties between ego and network members, and a support network in which the members are relatively loosely connected with one another (i.e., ego possesses "brokerage social capital"). These findings suggest the incorporation into therapeutic programming of interventions that address those aspects of clients' personal support networks.

Direct integration of III–V semiconductor light sources on silicon is an essential step toward the development of portable, on-chip infrared sensor systems. Driven by the presence of characteristic molecular fingerprints in the mid-infrared (MIR) spectral region, such systems may have a wide range of applications in infrared imaging, gas sensing, and medical diagnostics. This paper reports on the integration of an InAs virtual substrate and high crystalline quality InAs/InAsSb multi-quantum wells on Si using a three-stage InAs/GaSb/Si buffer layer. It is shown that the InAs/GaSb interface demonstrates a strong dislocation filtering effect. A series of strained AlSb/InAs dislocation filter superlattices was also used, resulting in a low surface dislocation density of approximately 4 × 107 cm−2. The InAs/InAsSb wells exhibited a strong photoluminescence signal at elevated temperatures. Analysis of these results indicates that radiative recombination is the dominant recombination mechanism, making this structure promising for fabricating MIR Si-based sensor systems.

We report on a mid-infrared resonant cavity light emitting diode (RCLED) operating at the wavelength of 4.5 µm with a narrow spectral linewidth at room temperature. Compared to a reference LED without a resonant cavity, our RCLED exhibits (85x) higher peak intensity, (13x) higher integrated output power, (16x) narrower spectral linewidth and (7x) superior temperature stability. The device consists of a one-wavelength thick micro-cavity containing an Al0.12In0.88As/InAs0.85Sb0.15 quantum well active region sandwiched between two high contrast AlAs0.08Sb0.92/GaSb distributed Bragg reflector mirrors, grown lattice–matched on GaSb by molecular beam epitaxy. The high spectral brightness, narrow linewidth and superior temperature stability are attractive features, enabling these devices to be used for detection of N2O at 4.5 µm. We show that with only minor adjustments the gases CO2 (4.2 µm) and CO (4.6 µm) are also readily accessible.

Hydrostatic pressure can be used as a powerful diagnostic tool to enable the study of lattice dynamics, defects, impurities and recombination processes in a variety of semiconductor materials and devices. Here we report on intermediate band GaAs solar cells containing GaSb quantum rings which exhibit a 15% increase in open-circuit voltage under application of 8 kbar hydrostatic pressure at room temperature. The pressure coefficients of the respective optical transitions for the GaSb quantum rings, the wetting layer and the GaAs bulk, were each measured to be ~ 10.5 ± 0.5 meV/kbar. A comparison of the pressure induced and temperature induced bandgap changes highlights the significance of the thermal energy of carriers in intermediate band solar cells.

There is considerable interest in the development of InAsSb-based nanowires for infrared photonics due to their high tunability across the infrared spectral range, high mobility, and integration with silicon electronics. However, optical emission is currently limited to low temperatures due to strong nonradiative Auger and surface recombination. Here, we present a new structure based on conical type II InAsSb/InAs multiquantum wells within InAs nanowires which exhibit bright mid-infrared photoluminescence up to room temperature. The nanowires are grown by catalyst-free selective area epitaxy on silicon. This unique geometry confines the electron-hole recombination to within the quantum wells which alleviates the problems associated with recombination via surface states, while the quantum confinement of carriers increases the radiative recombination rate and suppresses Auger recombination. This demonstration will pave the way for the development of new integrated quantum light sources operating in the technologically important mid-infrared spectral range.

We analyse the optical properties of InAs1−x Sb x /Al y In1−y As quantum wells (QWs) grown by molecular beam epitaxy on relaxed Al y In1−y As metamorphic buffer layers (MBLs) using GaAs substrates. The use of Al y In1−y As MBLs allows for the growth of QWs having large type-I band offsets, and emission wavelengths >3 m. Photoluminescence (PL) measurements for QWs having Sb compositions up to x = 10% demonstrate strong room temperature PL up to 3.4 m, as well as enhancement of the PL intensity with increasing wavelength. To quantify the trends in the measured PL we calculate the QW spontaneous emission (SE), using a theoretical model based on an eight-band Hamiltonian. The theoretical calculations, which are in good agreement with experiment, identify that the observed enhancement in PL intensity with increasing wavelength is associated with the impact of compressive strain on the QW valence band structure, which reduces the band edge density of states making more carriers available to undergo radiative recombination at fixed carrier density. Our results highlight the potential of type-I InAs1−x Sb x /Al y In1−y As metamorphic QWs to address several limitations associated with existing heterostructures operating in the mid-infrared, establishing these novel heterostructures as a suitable platform for the development of light-emitting diodes and diode lasers.

Assess gender and age segregation and stratification among co-offenders. The population comprises co-offenders aged 5–75 in police-reported co-offenses in Canada, 2006–2009. Segregation is indicated by observed and inbreeding homophily, measured with cross-tabulations and log-linear distance models. Stratification is assessed with elaborations by crime type. Intersectionality of gender and age status is estimated with interaction terms in the log-linear models. Female and younger offenders are over-represented among co-offenders. Co-offending exhibits gender and age status homophily: same-gender dyads are approximately twice as frequent as mixed-gender, and same-age-status dyads are almost 7 times as frequent as mixed-age-status. Gender homophily varies by crime type, being stronger in robbery, aggravated assault, common assault, and minor theft, and weaker in serious drug crime and homicide, and (especially) sex crimes against children. Age homophily is strong in all types of crime. Gender and age homophily have a negative interaction: dyads comprising a female child or youth and an adult male occur 1.4 times as frequently as predicted from the main effects of gender and age status. Female and younger offenders are not excluded from co-offending per se but, consistent with expectations from Blau’s (Inequality and heterogeneity. Free Press, New York, 1977) and Steffensmeier’s (Soc Forces 6:1010–1032, 1983) theories, they are segregated from co-offending with male and (especially) adult offenders. There was limited evidence of gender stratification, and no evidence of age stratification. The interaction of gender and age status in the segregation and stratification of co-offending attenuates their individual effects, contrary to expectations from feminist intersectionality theory and consistent with Blau’s (1977) theory.

We report on the open-circuit voltage recovery in GaSb quantum ring (QR) solar cells under high solar concentration up to 2500 suns. The detailed behaviour of type II GaSb/GaAs QR solar cells under solar concentration, using different temperatures and light illumination conditions, is analysed through optical and electrical measurements. Although enhancement of the short-circuit current was observed because of sub-bandgap photon absorption in the QR, the thermionic emission rate of holes was found to be insufficient for ideal operation. The direct excitation of electron–hole pairs into QRs has revealed that the accumulation of holes is one of the causes of the open-circuit voltage (VOC) degradation. However, using concentrated light up to 2500 suns, the GaSb QR cell showed much quicker VOC recovery rate than a GaAs control cell.

III-V semiconductor heterostructures grown on GaSb and InAs substrates are widely used to produce high performance optoelectronic devices operating in the technologically important mid-infrared spectral range. However, these substrates are expensive, only available in small sizes and have low thermal conductivity. Integration of III-Vs onto silicon substrates offers the opportunity to overcome these shortcomings and opens the possibility of new applications in lab-on-chip MIR photonic integrated circuits. However, the unusual III-V/Si interface and large lattice mismatch presents challenges to epitaxial growth. Here, we report on novel techniques employed to grow high quality Sb-based optoelectronic devices on silicon using molecular beam epitaxy.

This article examines age homophily among co-offenders, using data on approximately 440,000 co-offenses recorded by police in Canada during 2006 to 2009. Log-linear models for social mobility tables are applied to an 86-by-86 table of frequencies of co-offending among year-of-age groups for individuals from 3 to 88 years old. The results indicate strong age homophily for co-offenders of all ages, but decreasing with age. There is further structuration into four age groups: children (3-11 years), youth (12-17 years), young adults (18-45 years), and older adults (46-88 years). The “Fagin” hypothesis that offenders below the age of criminal responsibility are particularly attractive as co-offenders for older offenders is disconfirmed.

The authors report on the structural, the optical and the electrical properties of solar cells containing 20 layers of doped InAs/GaAs quantum dots (QDs). The structures were grown by molecular beam epitaxy and contain n dopant sheet densities of 8 and 16 × 1010cm−2, respectively, in between the QD layers. Under a 1 sun illumination, the open-circuit voltage (V oc) and the efficiency of the 8 × 1010cm−2 n-doped sample were increased to values of 0.73 V and 9.7%, respectively, compared with a reference undoped sample (a V oc of 0.70 V and an efficiency of 9.0%). However, the short-circuit current density (J sc) decreased from 20.1 to 17.4 mA/cm2 indicating bandfilling within the QD array.

The authors report on the analysis of the hole escape mechanisms from type-II GaSb quantum rings (QRs) embedded within the active region of a GaAs single junction solar cell. When the solar cell is excited by using a 1064 nm infrared laser with excitation energy lower than the bandgap of the GaAs matrix, photogenerated electron-hole pairs are created directly within the GaSb QRs. The QR photocurrent exhibits a linear dependence on the excitation intensity over several decades. The thermal activation energy was found to be weakly dependent on the incident light level and increased by only a few meV over several orders of excitation intensity. The magnitude of the relative absorption in the author's QRs when directly probed by using a 1064 nm laser with an incident power density of approximate to 2.6 W cm(-2) is found to be approximate to 1.4 x 10(-4) per layer. The thermal escape rate of the holes was calculated and found to be approximate to 10(11) to 10(12) s(-1), which is much faster than the radiative recombination rate 10(9) s(-1). This behaviour is promising for concentrator solar cell development and has the potential to increase solar cell efficiency under a strong solar concentration.

Trends in the seriousness of youth crime in Canada from 1984 to 2011 are assessed by analysing changes over time in the mix of offences for which young people have been reported by police as chargeable. Four indicators of seriousness are used: Statistics Canada crime seriousness weights, the proportion of youth accused of an indictable offence, a fivefold classification of offences; and a selection of high volume offences. All four analyses clearly indicate a substantial downward trend over the period in the overall seriousness of police-reported youth crime. The decline in seriousness is mainly due to a very large decrease in the proportion of youth accused of the serious offence of break and enter and a correspondingly large increase in the proportion accused of the minor offences of common assault, cannabis possession, and offences against the administration of justice. The proportion of chargeable youth accused of major offences against the person has increased substantially relative to its level in 1984, but it remains low compared to property and other offenders. Thus, reported youth crime in Canada has become proportionally more violent but less serious overall.

We report the successful molecular-beam epitaxial growth of 10 stacked layers of GaSb/GaAs quantum rings using a new procedure. Exact control of the arsenic flux during capping helps to reduce the strong group-V As–Sb exchange reactions, enabling the rings to be capped at the same growth temperature (480 °C) without dissolution. X-ray diffraction and transmission electron microscopy indicate excellent structural quality and uniformity with no threading dislocations. This is due to the reduction in the average strain through the quantum-ring formation. The total ring density in the stacks is 1 × 1011 cm–2. An unusually long-wavelength quantum-ring photoluminescence peak of 1.3 μm is observed at low temperature, which is attributed to a reduction in the quantum-ring charging due to lower unintentional p-doping in the GaAs cap layer. The impact that this effect will have on future device designs in solar cells and lasers is also discussed.

Novel InSb quantum dot (QD) nanostructures grown by molecular beam epitaxy (MBE) are investigated in order to improve the performance of light sources and detectors for the technologically important mid-infrared (2-5 μm) spectral range. Unlike the InAs/GaAs system which has a similar lattice mismatch, the growth of InSb/InAs QDs by MBE is a challenging task due to Sb segregation and surfactant effects. These problems can be overcome by using an Sb-As exchange growth technique to realize uniform, dense arrays (dot density ~1012 cm-2) of extremely small (mean diameter ~2.5 nm) InSb submonolayer QDs in InAs. Light emitting diodes (LEDs) containing ten layers of InSb QDs exhibit bright electroluminescence peaking at 3.8 μm at room temperature. These devices show superior temperature quenching compared with bulk and quantum well (QW) LEDs due to a reduction in Auger recombination. We also report the growth of InSb QDs in InAs/AlAsSb ‘W’ QWs grown on GaSb substrates which are designed to increase the electron-hole (e-h) wavefunction overlap to ~75%. These samples exhibit very good structural quality and photoluminescence peaking near 3.0 μm at low temperatures.

La Loi sur le systeme de justice penale pour les adolescents (2003) a ete promulguee dans le but de diminuer le recours aux tribunaux et a la detention pour les jeunes contrevenants, et a ameliorer l’efficacite des mesures prises dans les cas de violence criminelle grave commise par des jeunes. Dans l’article, on evalue l’impact qu’a eu la Loi au cours des cinq annees suivant son adoption. On y passe en revue les principales dispositions de la Loi touchant la determination de la peine et les mesures extrajudiciaires. On y parle aussi de la jurisprudence de la Cour supreme du Canada quant a l’interpretation de la Loi et on presente des donnees statistiques sur l’impact qu’a eu la Loi sur les mesures extrajudiciaires et la determination de la peine chez les adolescents, ainsi que sur le nombre de cas juges devant les tribunaux et en detention. La Cour supreme a interprete de maniere restrictive les dispositions de la Loi permettant de recourir a la detention, ce qui a contribue a faire diminuer le taux de detention. La Cour a aussi insiste sur le fait qu’il faut traiter les jeunes differemment des adultes. De plus, elle a juge inconstitutionnelles les dispositions de la Loi creant une presomption de peine applicable aux adultes pour les jeunes contrevenants les plus violents, limitant ainsi les effets de certains articles de la Loi visant les crimes graves avec violence. Grâce a la Loi, le taux de recours aux tribunaux et a la detention ont considerablement diminue, sans que la criminalite enregistree chez les jeunes augmente pour autant. Il existe encore des variations importantes d’une region a l’autre du recours aux tribunaux de la jeunesse et de detention chez les jeunes. Meme s’il y a moins de differences regionales liees au recours aux tribunaux depuis l’adoption de la Loi, il n’y a pas vraiment eu de changement quant a la detention apres son entree en vigueur. La criminalite chez les jeunes demeure un sujet de preoccupation politique litigieux au Canada. Abstract: The Youth Criminal Justice Act (2003) was enacted with the intent of decreasing the use of courts and restricting the use of custody for adolescent offenders, while improving the effectiveness of the responses to serious violent youth offenders. This paper assesses the impact of the act in its first five years. It reviews salient provisions of the act dealing with sentencing and diversion, discusses Supreme Court of Canada jurisprudence interpreting the act, and presents statistical data on the impact of the YCJA on diversion and sentencing of youth and on youth court and custodial caseloads. The Supreme Court has narrowly interpreted the provisions of the YCJA that allow for the use of custody, contributing to a reduction in use of custody. The Court has also emphasized that youth are to be treated differently from adults and ruled unconstitutional provisions of the YCJA that created a presumption of adult sentencing for the most serious offences by young offenders, limiting the effect of provisions of the act directed at serious violent offenders. The YCJA has succeeded in significantly reducing the rates of use of court and custody, without increasing recorded youth crime. There continue to be significant regional variations in rates of use of youth courts and custody. Although regional differences in the use of court have declined under the YCJA, variation in the use of custody has not been significantly affected by the new act. Youth crime remains a contentious political concern in Canada.

GaSb p–i–n photodiodes were grown on GaAs and Si, using interfacial misfit arrays, and on native GaSb. For the samples grown on GaAs and Si, high-resolution transmission electron microscopy images revealed interface atomic periodicities in agreement with atomistic modeling. Surface defect densities of ~View the MathML source were measured for both samples. Atomic force microscopy scans revealed surface roughnesses of around 1.6 nm, compared with 0.5 nm for the sample grown on native GaSb. Dark current and spectral response measurements were used to study the electrical and optoelectronic properties of all three samples.

We report on the fabrication of GaAs based p–i–n solar cells containing 5 and 10 layers of type II GaSb quantum rings grown by molecular beam epitaxy. Solar cells containing quantum rings show improved efficiency at longer wavelengths into the near-IR extending up to 1500 nm and show enhanced short-circuit current under 1 sun illumination compared to a GaAs control cell. A reduction in the open-circuit voltage is observed due to the build-up of internal strain. The MBE growth, formation and photoluminescence of single and stacked layers of GaSb/GaAs quantum rings are also presented.

The concept of social exclusion is used to explore the relationship between people and groups who are socially and economically disadvantaged and the phenomenon of going missing. Police data about missing persons are compared to census data to determine whether groups who experience family dissolution, labour market exclusion, and other forms of disadvantage and social exclusion are overrepresented among missing persons compared to the general population. The analysis shows that disadvantaged youth, women, Aboriginal people, people who are not in the labour force, unemployed people, and homeless people are all overrepresented among missing persons. People occupying the intersections of multiple high risk categories are at particularly high risk of going missing. Linking missing persons with the concept of social exclusion shows that social and economic disadvantage lead directly and indirectly to peoples’ disappearances. (133 words)

There is a consensus that some racial groups are over-represented in their contact with the Canadian justice system, but a lack of agreement about possible reasons for this over-representation. The two dominant explanations for disproportionate minority contact (DMC) with the police are differential involvement in crime and differential treatment by the police. Differential treatment may be due to disproportionate possession by minorities of risk factors for police contact or to discriminatory policing. This paper uses data on self-reported delinquency and police contacts from a representative sample of Canadian youth aged 12 to 17 years from the National Longitudinal Study of Children and Youth to test the hypotheses that DMC is due to differential involvement or to differential treatment due to disproportionate risk factors. The results indicate that there was disproportionate minority contact with the police, but no support was found for explanations of DMC in terms of either differential involvement or differential treatment due to risk factors. Distinguishing between youth who report violent delinquency and all other youth, DMC was found only for the non-violent youth; this DMC was also not explained by differential treatment due to risk factors. By eliminating other explanations, the results suggest that racially discriminatory policing may be one explanation for DMC in Canada.

Electroluminescence is reported from dilute nitride InAsSbN/InAs multiquantum well light-emitting diodes grown using nitrogen plasma source molecular beam epitaxy. The diodes exhibited bright emission in the midinfrared peaking at 3.56 μm at room temperature. Emission occurred from a type I transition from electrons in the InAsSbN to confined heavy and light hole states in the QW. Analysis of the temperature- and current-dependent electroluminescence shows that thermally activated hole leakage and Auger recombination are the performance limiting factors in these devices.

The liquid phase epitaxial growth of pentanary GaInAsSbP lattice matched onto InAs substrates is reported for use in narrow bandgap thermophotovoltaic cells. The epitaxial layers were characterised and exhibited bright photoluminescence up to room temperature. Prototype thermophotovoltaic cells were fabricated, which were sensitive in the mid-infrared spectral range having cut-off wavelengths in the range 4.0-4.5 mu m at room temperature. (C) 2010 Elsevier B.V. All rights reserved.

We present the results of an investigation into the growth of InGaSb/GaAs quantum dots (QDs) by molecular beam epitaxy using migration-enhanced epitaxy. Surface atomic force microscopy and cross-sectional transmission electron microscopy show that the QDs undergo a significant change in morphology upon capping with GaAs. A GaAs ‘cold capping’ technique was partly successful in preserving QD morphology during this process, but strong group V intermixing was still observed. Energy-dispersive x-ray spectroscopy reveals that the resulting nanostructures are small ‘core’ QDs surrounded by a highly intermixed disc. Temperature varying photoluminescence measurements indicate strong light emission from the QDs, with an emission wavelength of 1230 nm at room temperature. Nextnano 8x8 k.p calculations show good agreement with the PL results and indicate a low level of group-V intermixing in the core QD.

This article examines the role of co-offending in the development of the delinquent career. Hypotheses derived from Reiss's (1986, 1988) taxonomic theory of co-offending are tested, using police-reported data on the delinquent careers and co-offending of 55,336 Canadian offenders. Support is found for a taxonomic theory and for age-related and functional theories of co-offending. The taxonomy consists of two types of offenders-high activity (3 percent) and low activity (97 percent)-whose co-offending patterns differ during the teenage years but not during childhood. For low-activity offenders as teenagers, the proportion of co-offenses decreases with criminal experience. The rate of co-offending by high-activity offenders as teenagers is lower at onset than for low-activity offenders, and it varies little with criminal experience. For both offender types, the proportion of co-offenses decreases with age, is slightly less in males, and varies with the type of offense. For both offender types, the proportion of co-offenses in childhood offending is greater than in the teenage years and is unrelated to the offender's age or criminal experience.

We report the molecular beam epitaxial growth of InSb quantum dots (QD) inserted as sub-monolayers in an InAs matrix which exhibit intense mid-infrared photoluminescence up to room temperature. The InSb QD sheets were formed by briefly exposing the surface to an antimony flux (Sb2) exploiting an As-Sb anion exchange reaction. Light emitting diodes were fabricated using 10 InSb QD sheets and were found to exhibit bright electroluminescence with a single peak at 3.8μm at room temperature.

This article addresses Carol La Prairie's (1992; 2002) hypothesis that the over-representation of Aboriginal people in the Canadian criminal justice system is, to a considerable extent, due to their disadvantaged urban living conditions. Specifically, it investigates the sources of the high level of police-reported Aboriginal crime in Winnipeg in 2001. Geocoded crime incident data from the incident-based Uniform Crime Reporting Survey and Census data for the City of Winnipeg are combined in a neighbourhood-level ecological analysis of urban Aboriginal crime. The results indicate that a substantial part of the elevated level of police-reported Aboriginal crime is explained by the structural characteristics of the neighbourhoods in which Aboriginal people tend to live. These results confirm La Prairie's hypothesis and point to the importance of considering community conditions in understanding and preventing crime.

This article examines the impact of the Youth Criminal Justice Act of 2002 on police discretion with apprehended young offenders in Canada. Data for 1986 to 2005 from the Canadian Uniform Crime Reporting Survey are analyzed using an interrupted time series design. The Youth Criminal Justice Act was successful in achieving its objective of reducing youth court referrals by structuring police discretion. It caused a substantial change in the exercise of police discretion with apprehended youth: a substantial decrease in the use of charges and a corresponding increase in the use of alternatives to charging. The substitution of extrajudicial measures for charges occurred in all four regions of Canada and was much greater with minor offenses than with serious youth crime. Possible reasons for the success of the Youth Criminal Justice Act are discussed.

There are many applications for mid-infrared light sources which has stimulated intensive research into the physics and technology of narrow gap materials and devices. In this article we give an overview of the development of mid-infrared LEDs and diode lasers being studied in our laboratory. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)