Search

Objective Recent studies have examined the extent to which alcohol dependence (AD) criteria prospectively predict the course of AD. Critically, these studies have lacked a developmental perspective. However, the differential performance of criteria by age might indicate overendorsement in younger individuals. The current study examined AD criteria in terms of persistence and prediction of AD course and alcohol use by age in order to identify criteria that are likely to be overly endorsed by younger individuals. Method The current study used longitudinal data from the National Epidemiologic Survey on Alcohol and Related Conditions to depict age differences in rates of new onset, recurrence, and persistence for each AD criterion, thereby showing how these three factors contribute to the overall age-prevalence curve of each criterion. Additionally, we tested age moderation of the predictive association between each criterion at baseline and new onset, recurrence, and persistence of syndromal AD. Results Some criteria (particularly, persistent desire or unsuccessful efforts to cut down or control drinking, and drinking despite physical/psychological problems) are both less persistent and less predictive of AD course among younger adults compared to older adults. Conclusions These findings raise the possibility of elevated rates of false-positive AD among younger adults and suggest ways to improve the assessment of AD criteria. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Scholars of classical economics have largely rejected the popular view of Adam Smith as an apologist for big business indifferent to the plight of the poor. To test and ultimately vindicate this consensus, I attempt to tabulate all mentions of the poor in Smith's published works in which their well-being is under discussion. For each such appearance I assess his attitude toward such well-being, as well as where his sympathies lie should there be a conflict between the poor on one side and the rich and powerful on the other. The textual search strongly supports the idea that Smith was indeed partial to workers and the poor, although this judgment requires that the reader enter into Smith's patterns of thought about property rights, economic growth, and the system of natural liberty.

Modified boron-coated straw (BCS) detector configurations are introduced, in order to improve detection efficiency, and reduce the number of layers required to match the response of high-pressure 3He tubes, in large-scale neutron science instruments. A new 7-straw design employing thin-walled aluminum tubes facilitates operation in vacuum, and substantially reduces the scattering material by a factor of 5 compared with the flow-through design of the Multi-Grid detector. Another design introduces 18 radial walls inside each straw, coated on both sides with enriched boron carbide, to increase the coated wall perimeter 4.3 times. The so-called Pie straw offers a significant benefit in detection efficiency compared with round straws used in LoKI. An example of such a straw having 18 septa is explored in modeling and experimental studies, that can potentially reduce the number of layers needed in large-scale instruments like LoKI by a factor of 2.8. In a parallel development, a totally new configuration of boron-coated detectors is introduced, aimed to address the need for high spatial resolution, and high-rate capability in single crystal diffractometers, like MaNDi and TOPAZ at the SNS, and in neutron reflectometers. The proposed structure is a close-packed array of rectangular cells, each fabricated by wrapping copper foil having a coating of 10B4C on one side and electroplated tin on the other side, around precisely machined rectangular bars. The array is pressed together and then vacuum brazed together. The resulting structure is quite strong and precise in geometry. This so-called Microcell Straw Array can be configured with channel dimensions as small as 0.5 mm × 2.5 mm. Due to its ultra thin walls (25 μm) secondary scattering of neutrons is minimized. It is sealed inside a fully welded thin aluminum containment vessel that allows convenient operation in vacuum. A mature low power readout system capable of an estimated count rate of 22 MHz in a 15 × 15 cm2 detector is also proposed. The improvements are the result of recent advances in BCS design, spurred by the development of compact, high-sensitivity monitors for homeland security and military applications.

This paper examines Hayek's constitutional theory of the liberal state. Hayek argued powerfully that no central planner has sufficient knowledge to run an economy, and that no one has sufficient knowledge to determine ends for others. Pushed to their logical conclusion, these arguments would seem to prescribe the smallest possible state in both scope and size, or perhaps even no state at all. Elsewhere in his writings, however, Hayek explicitly endorsed government activity that goes far beyond a “night watchman” state (to include public works such as infrastructure, roads and bridge, as well as social insurance, conscription, a minimum safety net, and even countercyclical investment)—as long as state action was carefully constrained by a generality principle. After thoroughly setting forth Hayek's worries about knowledge and his proposals for acceptable station action, the paper synthesizes the two into a Hayekian constitutional theory of the liberal state, then closes with a brief discussion of some tensions in Hayek's work.

The eustachian valve is an uncommon embryologic remnant of the sinus venosus present in the right atrium that may persist in some adults. Typically, in adults, right sided valvular endocarditis is associated with intravenous drug use or presence of central venous of hemodialysis catheters. Eustachian valve endocarditis is a rare cause of right sided endocarditis with very few cases reported. A routine transthoracic echocardiogram (TTE) may not be sensitive and miss this infection. Pasteurella multocida is gram negative microorganism that can rarely cause infective endocarditis. We present what we believe to be the first reported case of Eustachian valve endocarditis (EVE) caused by P. multocida.

Psychiatric diagnostic systems, such as The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), use expert consensus to determine diagnostic criteria sets and rules (DCSRs), rather than exploiting empirical techniques to arrive at optimal solutions (OS). Our project utilizes complete enumeration (i.e., generating all possible subsets of item combinations A and B with all possible thresholds, T) to evaluate all possible DCSRs given a set of relevant diagnostic data. This method yields the entire population distribution of diagnostic classifications (i.e., diagnosis of the disorder versus no diagnosis) produced by a set of dichotomous predictors (i.e., diagnostic criteria). Once unique sets are enumerated, optimization on some predefined correlate or predictor will maximally separate diagnostic groups on one or more, disorder-specific “outcome” criteria. We used this approach to illustrate how to create a common Substance Use Disorder (SUD) DCSR that is applicable to multiple substances. We demonstrate the utility of this approach with respect to alcohol use disorder and Cannabis Use Disorder (CUD) using DSM-5 criteria as input variables. The optimal SUD solution with a moderate or above severity grading included four criteria (i.e. 1) having a strong urge or craving for the substance (CR), 2) failure to fulfill major role obligations at work school or home (FF), 3) continued use of the substance despite social or interpersonal problems caused by the substance use (SI) and 4) physically hazardous use (HU)) with a diagnostic threshold of two. The derived DCSR was validated with known correlates of SUD and performed as well as DSM-5. Our findings illustrate the value of using an empirical approach to what is typically a subjective process of choosing criteria and algorithms that is prone to bias. The optimization of diagnostic criteria can reduce criteria set sizes, resulting in decreased research, clinician, and patient burden.

We consider scheduling problems in which jobs must be processed through a (shared) network of machines. The network is given in the form of a graph, the edges of which represent the machines. We are also given a set of jobs, each specified by its processing time and a path in the graph. Every job must be processed in the order of edges specified by its path. We assume that jobs can wait between machines and preemption is not allowed; that is, once a job starts processing on a machine, it must be completed without interruption. Every machine can only process one job at a time. The makespan of a schedule is the earliest time by which all the jobs have finished processing. The completion time of a job in a schedule is defined as the time it finishes processing on its last machine. The total completion time refers to the sum of completion times of all the jobs. Our focus is on finding schedules with the minimum sum of completion times or minimum makespan. In this paper, we develop several algorithms (both approximate and exact) for the problem both on general graphs and when the underlying graph of machines is a tree. Even in the very special case when the underlying network is a simple star, the problem is very interesting as it models a biprocessor scheduling with applications to data migration.

Binge drinking, commonly defined as consuming five or more standard drinks per occasion for men and four or more drinks for women, typically begins in adolescence. Adolescents, although they may drink less often, tend to consume higher quantities of alcohol per occasion compared with adults. This developmental difference in pattern of alcohol consumption may result, in part, from maturational changes that involve an adolescent-specific sensitivity to certain alcohol effects and greater propensity for risk-taking behaviors, such as binge drinking. Adolescent binge drinking is associated with a range of acute alcohol-related harms, some of which may persist into adulthood. The prevalence of binge drinking, including high-intensity drinking (i.e., 10 or more and 15 or more drinks per occasion), has declined among adolescents in recent years. Overall, however, the proportion of youth who engage in binge drinking remains high. This article reviews the definition and prevalence of binge drinking in adolescence, trajectories of binge drinking and their correlates, and implications for prevention.

We have developed a large-area, low-cost, high-efficiency neutron detector for vehicle-mounted operation. The detector, which has overall dimensions 12.7 cm $\times 91.4$ cm $\times 102$ cm (5” $\times 36$ ” $\times 40$ ”), a sensitive area equal to $0.85~\text {m}^{{\mathbf {2}}}$ (1320 in2), and weight of 110 kg (242 lbs), employs an array of 90 boron-coated straw (BCS) detectors. PTI has also developed electronics to minimize cost and space while providing low-noise signal conditioning for both neutron and gamma detection channels, as well as low energy Bluetooth communication with handheld devices. Extremely low power consumption allows continuous use for 225 hours (~10 days) using three AAA lithium-ion rechargeable batteries. We present radiological, mechanical, and environmental tests, collected from four full-scale prototypes. Outdoor neutron-counting tests with a moderated 252Cf source 2 m away from the center of the detector face showed an average detection rate of 5.5 cps/ng with a standard deviation of 0.09 cps/ng over the four individual detector measurements. Measurements showed a gamma rejection ratio of $1.0\times 10^{{\mathbf {-8}}}$ , and gamma absolute rejection ratio (GARRn) of 0.93. The prototypes were also operated successfully onboard a moving vehicle for high-speed tests and a long-range 1433-mile, two-day road trip from Houston, TX, USA, to Laurel, MD, USA. Using auxiliary DARPA SIGMA equipment, the GPS, timestamp, gamma and neutron data were transmitted over the cellular network with 10 Hz resolution to a server and real-time tracking website. Mechanical impact and electrostatic discharge testing produced no spurious counts in either the neutron or gamma channels. Ambient environmental temperature testing showed less than ± 1% response variation over the range from −30°C to +55°C.

We study variants of the capacitated vehicle routing problem. In the multiple depot capacitated k-travelling repairmen problem (MD-CkTRP), we have a collection of clients to be served by one vehicle in a fleet of k identical vehicles based at given depots. Each client has a given demand that must be satisfied, and each vehicle can carry a total of at most Q demand before it must resupply at its original depot. We wish to route the vehicles in a way that obeys the constraints while minimizing the average time (latency) required to serve a client. This generalizes the Multi-depot k-Travelling Repairman Problem (MD-kTRP) (Chaudhuri et al. in 44th IEEE-FOCS, pp 36–45, 2003; Post and Swamy in 26th ACM-SIAM SODA, pp 512–531, 2015) to the capacitated vehicle setting, and while it has been previously studied (Lysgaard and Wholk in Eur J Oper Res 236(3):800–810, 2014), no approximation algorithm with a proven ratio is known. We give a 42.49-approximation to this general problem, and refine this constant to 25.49 when clients have unit demands. As far as we are aware, these are the first constant-factor approximations for capacitated vehicle routing problems with a latency objective. We achieve these results by developing a framework allowing us to solve a wider range of latency problems, and crafting various orienteering-style oracles for use in this framework. We also show a simple LP rounding algorithm has a better approximation ratio for the maximum coverage problem with groups (MCG), first studied by Chekuri and Kumar (Approximation, randomization, and combinatorial optimization, algorithms and techniques, pp 72–83, 2004), and use it as a subroutine in our framework. Our approximation ratio for MD-CkTRP when restricted to uncapacitated setting matches the best known bound for it (Post and Swamy in 26th ACM-SIAM SODA, pp 512–531, 2015). With our framework, any improvements to our oracles or our MCG approximation will result in improved approximations to the corresponding k-TRP problem.

The Biphasic Alcohol Effects Scale (BAES) is widely used to assess stimulant and sedative alcohol effects. This paper reviews (a) recent measurement developments, (b) behavioral and physiological correlates, and (c) the role of the BAES in refining theories of SR and pharmacological interventions. An abbreviated scale (B-BAES) and a comprehensive measures of alcohol effects (SEAS) demonstrate strong psychometric properties and use of the BAES has helped refine the Differentiator Model of SR. Importantly, both BAES stimulation and sedation robustly predict risk for later alcohol problems, and the BAES has demonstrated utility in examining mechanisms of pharmacotherapy effects. The BAES is the most widely used measure of SR and has informed both theory and practice. Recent findings point to important future directions including the need to (a) examine developmental influences, (b) refine our understanding of FH effects, and (c) consider expansion to capture novel aspects of SR.

What are the limits of collective action? As James Buchanan famously worried, is it possible to empower the productive state without lapsing into the predatory state? This paper uses insights from F.A. Hayek to address problems of public goods and the role of the state. Hayek convincingly argued that no central planner has sufficient knowledge to run an economy. Yet Hayek also allowed for state provision of some goods beyond the prevention of coercion. The question, then, is whether Hayek’s safeguards offer a satisfactory response to Buchanan’s worry. This paper contends that Hayek violated his own conditions for permissible government activity. Nevertheless, he offers a serious research agenda for limiting state abuses.

A neutron imaging detector, based on boron-coated straws (BCS), a technology aimed to replace 3He tubes in large- scale neutron science instruments, has been tested at the China Spallation Neutron Source (CSNS), a recently commissioned neutron science facility in Dongguan, China. The detector consists of bundles of straws, each 7.5 mm in diameter, 1 m in active length, coated on the inside with a pure layer of 10B- enriched boron carbide (10B 4 C). A total of 231 BCS are employed in the full imaging panel, which has a sensitive area of 0.18×1.0 m2. We present results of initial testing with a collimated neutron beam designed to determine spatial resolution, and a series of planned improvements, including the replacement of the copper straw wall with aluminum to minimize scattering, design modifications that allow operation inside vacuum, and a fast amplifier that can achieve a pulse width on the order of tens of nanoseconds.

Prototypes of in-house developed boron-coated straw (BCS) detectors have been tested in the thermal and cold neutron energy ranges. Their neutron detection performance has been benchmarked against the industry standard (detector tubes filled with 3 He gas). The tests show that the BCS detectors perform near their theoretical limit regarding the detection efficiency, which is adequate for scientific instruments in the cold neutron energy range. The BCS detectors perform on par with 3 He tubes in terms of signal to noise and timing resolution, and superior regarding longitudinal spatial resolution.

BACKGROUND AND AIMS: Nearly all the research conducted on high-intensity drinking has focused on college and school-based samples, with recent calls for research to understand this risky drinking pattern in non-school-based samples and across time. This study aimed to characterize predictors and consequences of non-binge drinking, age- and gender-adjusted binge drinking (level I) and drinking at levels representing two or more times (level II) and three or more times the level I binge threshold (level III) in a clinical sample of adolescents followed into young adulthood. DESIGN: Cross-sectional associations between non-binge drinking, binge levels, and negative alcohol-related consequences were examined during adolescence; prospective analyses tested whether adolescent non-binge drinking and binge levels predicted alcohol use disorder (AUD) symptoms in young adulthood and whether changes in drinking motives over time were associated with binge levels in young adulthood. SETTING: US clinical settings. PARTICIPANTS: A total of 432 adolescents (aged 12–18 years) with alcohol-related problems followed into young adulthood (aged 19–25 years). MEASUREMENTS: Life-time drinking history, Structured Clinical Interview for DSM AUDs, and Inventory of Drinking Situations. FINDINGS: Results were generally consistent with a distinction between binge level I versus levels II–III on various negative alcohol-related consequences in adolescence (Ps < 0.05) that were maintained in young adulthood (Ps < 0.01). The maintenance of relatively high endorsement of enhancement and social motives over time was associated with binge levels II–III in young adulthood (Ps < 0.001); decreases in coping motives were associated with less risky drinking in adulthood (P = 0.003). CONCLUSIONS: Among US adolescents with alcohol-related problems who were followed-up in young adulthood (aged 19–25 years), standard threshold binge drinking (five or more drinks per occasion; level I) was generally associated with fewer alcohol-related consequences and problem behaviors than binge drinking at two or more times (level II) or three or more times (level III) the standard binge threshold.

BACKGROUND: Alcohol withdrawal (AW) is an important clinical and diagnostic feature of alcohol dependence. AW has been found to predict a worsened course of illness in clinical samples, but in some community studies AW endorsement rates are strikingly high, suggesting false positive symptom assignments. Little research has examined the validity of the DSM-5 algorithm for AW, which requires either the presence of at least 2 of 8 sub-criteria (i.e., autonomic hyperactivity, tremulousness, insomnia, nausea, hallucinations, psychomotor agitation, anxiety, and grand mal seizures), or, the use of alcohol to avoid or relieve these symptoms. METHOD: We used item and algorithm analyses of data from waves 1 and 2 of the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC; current drinkers, n = 26,946 at wave 1) to study the validity of DSM-5 AW as operationalized by the Alcohol Use Disorder and Associated Disabilities Interview Schedule-DSM-IV (AUDADIS-IV). RESULTS: A substantial proportion of individuals given the AW symptom reported only modest to moderate levels of alcohol use and alcohol problems. Alternative AW algorithms were superior to DSM-5 in terms of levels of alcohol use and alcohol problem severity among those with AW, group difference effect sizes, and predictive validity at a three-year follow-up. The superior alternative algorithms included those that excluded the nausea sub-criterion; required withdrawal-related distress or impairment; increased the AW sub-criteria threshold from 2 to 3 items; and, required tremulousness for AW symptom assignment. CONCLUSIONS: The results indicate that the DSM-5 definition of AW, as assessed by the AUDADIS-IV, has low specificity. This shortcoming can be addressed by making the algorithm for symptom assignment more stringent.

Generations of readers have nodded in agreement with Adam Smith’s argument, in Book One of the Wealth of Nations, that a nation cannot be happy if the workers who constitute the majority of its population are miserable. Smith notes that equity, besides, demands that workers receive a generous recompense for their labor. I contend that this famous statement is best interpreted in light of contemporary arguments that it was socially useful for workers to be poor. Smith’s engagement with these arguments is usually interpreted with reference to the labor supply function, but I argue that it also involved deeper suppositions about the place of workers in the social order. Smith’s reaction to these suppositions enriches our understanding of his contribution to liberal economics.

AIMS: This study examined the personality traits of negative emotionality and constraint and the ability to resist drinking during negative affective states as correlates of solitary drinking in adolescence. We hypothesized that higher levels of negative emotionality and lower levels of constraint would predict solitary drinking and that these relationships would be mediated by the ability to resist drinking in response to negative emotions. DESIGN: Structural equation modeling was used to fit a path model from the personality traits of negative emotionality and constraint to solitary drinking status through intermediate effects on the ability to resist drinking during negative emotions using cross-sectional data. SETTING: Clinical and community settings in Pennsylvania, USA. PARTICIPANTS: The sample included 761 adolescent drinkers (mean age = 17.1). MEASUREMENTS: Adolescents completed the Lifetime Drinking History, the Multidimensional Personality Questionnaire, the Constructive Thinking Inventory, and the Situational Confidence Questionnaire. FINDINGS: The path model provided good fit to the data. The association between trait negative emotionality and solitary drinking was fully mediated by adolescents' ability to resist drinking during negative affective states (OR=1.05, b=.05, p=.01). In contrast, constraint had a direct effect on solitary drinking (OR=.79, b=-.23, pCONCLUSIONS: The ability to resist drinking while experiencing negative feelings or emotions may be an important underlying mechanism linking trait negative emotionality (a tendency toward depression, anxiety, and poor reaction to stress) and constraint (lack of impulsiveness) to adolescent solitary drinking. Language: en

© 2017 Clark, Chung, Martin, Hasler, Fitzgerald, Luna, Brown, Tapert, Brumback, Cummins, Pfefferbaum, Sullivan, Pohl, Colrain, Baker, De Bellis, Nooner and Nagel. During adolescence, problems reflecting cognitive, behavioral and affective dysregulation, such as inattention and emotional dyscontrol, have been observed to be associated with substance use disorder (SUD) risks and outcomes. Prior studies have typically been with small samples, and have typically not included comprehensive measurement of executive dysfunction domains. The relationships of executive dysfunction in daily life with performance based testing of cognitive skills and structural brain characteristics, thought to be the basis for executive functioning, have not been definitively determined. The aims of this study were to determine the relationships between executive dysfunction in daily life, measured by the Behavior Rating Inventory of Executive Function (BRIEF), cognitive skills and structural brain characteristics, and SUD risks, including a global SUD risk indicator, sleep quality, and risky alcohol and cannabis use. In addition to bivariate relationships, multivariate models were tested. The subjects (n = 817; ages 12 through 21) were participants in the National Consortium on Alcohol and Neurodevelopment in Adolescence (NCANDA) study. The results indicated that executive dysfunction was significantly related to SUD risks, poor sleep quality, risky alcohol use and cannabis use, and was not significantly related to cognitive skills or structural brain characteristics. In multivariate models, the relationship between poor sleep quality and risky substance use was mediated by executive dysfunction. While these cross-sectional relationships need to be further examined in longitudinal analyses, the results suggest that poor sleep quality and executive dysfunction may be viable preventive intervention targets to reduce adolescent substance use.

Background Proposed International Classification of Diseases, 11th edition (ICD-11) criteria for substance use disorder (SUD) radically simplify the algorithm used to diagnose substance dependence. Major differences in case identification across Diagnostic and Statistical Manual (DSM) and ICD impact determinations of treatment need and conceptualizations of substance dependence. This study compared the draft algorithm for ICD-11 SUD against DSM-IV, DSM-5, and ICD-10, for alcohol and cannabis. Methods Adolescents (n=339, ages 14-18) admitted to intensive outpatient addictions treatment completed, as part of a research study, a Structured Clinical Interview for DSM SUDs (SCID) adapted for use with adolescents, and which has been used to assess DSM and ICD SUD diagnoses. Analyses examined prevalence across classification systems, diagnostic concordance, and sources of diagnostic disagreement. Results Prevalence of any past year proposed ICD-11 alcohol or cannabis use disorder was significantly lower compared to DSM-IV and DSM-5 (ps

Background Sleep disturbances are both common and well-characterized in adults with alcohol use disorders (AUDs), but have received little study in adolescents with AUDs. Furthermore, a handful of studies suggest that sleep complaints are a risk factor for AUDs. However, no published studies have yet examined the longitudinal course of sleep complaints in adolescents with AUDs; in particular, it remains unclear how persistent AUD-associated sleep complaints are in this age group, and what types of sleep complaints are most relevant to alcohol-use symptoms. We investigated these questions in a 5-year longitudinal study of adolescents with and without AUDs at baseline. Methods Participants were 696 adolescents (age 12 to 19) from a longitudinal study at the Pittsburgh Adolescent Alcohol Research Center. At baseline, 347 participants had a current AUD (AUD+), while 349 had no current or past AUD (AUD−). We examined sleep and alcohol involvement at baseline as well as 1-, 3-, and 5-year follow-up visits. Sleep variables included self-reported insomnia and hypersomnia, as well as variability in weekday–weekend sleep duration, all at baseline. Covariates included sex, age, current alcohol symptoms, and depression severity. Results The AUD+ group reported more overall sleep disturbance at baseline, including greater insomnia and hypersomnia complaints, and greater variability in weekday–weekend sleep duration. Group differences in insomnia and hypersomnia complaints persisted to the 5- and 3-year follow-ups, respectively. In the AUD− group, greater insomnia complaints at baseline predicted an increase in alcohol symptoms at the 1-year follow-up, while greater variability in sleep duration at baseline predicted an increase in alcohol symptoms at the 3- and 5-year follow-ups. Conclusions These results complement previous findings in other samples, indicating that insomnia and other sleep problems are a chronic predicament for adolescents with AUDs. The findings also suggest that sleep disturbances may place adolescents without AUDs at an elevated risk of developing alcohol problems.

Aims This commentary critically evaluates the use of substance-related negative psychosocial and health consequences to define and diagnose alcohol and other substance use disorders. Methods Narrative review. Results The consequences of substance use cause much suffering and are major public health and economic problems. However, there are a number of conceptual and measurement problems with using consequences as diagnostic criteria for substance disorders. Data indicate that substance-related consequences introduce systematic bias and degrade the validity of diagnostic systems. Conclusions Negative psychosocial and health consequences of substance use should play a fundamentally reduced role in modern diagnostic systems for, and definitions of, addictive disorders.

Adolescent solitary drinking may represent an informative divergence from normative behavior, with important implications for understanding risk for alcohol-use disorders later in life. Within a self-medication framework, we hypothesized that solitary alcohol use would be associated with drinking in response to negative affect and that such a pattern of drinking would predict alcohol problems in young adulthood. We tested these predictions in a longitudinal study in which we examined whether solitary drinking in adolescence (ages 12–18) predicted alcohol-use disorders in young adulthood (age 25) in 466 alcohol-using teens recruited from clinical programs and 243 alcohol-using teens recruited from the community. Findings showed that solitary drinking was associated with drinking in response to negative affect during adolescence and predicted alcohol problems in young adulthood. Results indicate that drinking alone is an important type of alcohol-use behavior that increases risk for the escalation of alcohol use and the development of alcohol problems.

The limited inventory and minute natural abundance of 3He gas on Earth necessitate the adoption of new technologies for the detection of neutrons, especially in homeland security applications, where large volume deployments are required. We investigate the neutron detection efficiency of a backpack radiation detector based on an unmoderated array of boron-coated straws (BCS). A neutron module was configured that would be light and small enough to fit inside a regular-sized backpack. The module consisted of 36 tubes, arranged in two rows, for a total number of BCS detectors equal to 36 × 7=252. The overall dimensions of the neutron module were 3.18 cm × 26.7 cm × 38.1 cm, and its weight was 1.62 kg (3.57 lbs). The module was fitted immediately inside the back side of the backpack. The detectors are thus very close to the torso of the operator, which, together with a plastic scintillator for gamma detection, act as moderators for high-energy neutrons. In order to maintain a low weight, no other moderating material was installed inside the backpack. The weight of the pack containing both neutron and gamma detector panels, along with foam packing, electronics, and battery, was 5.36 kg (11.8 lbs). The compact dimensions of the design afforded use of a computer style backpack of minimal dimension providing significant additional operational advantages. The testing results indicate that, through use of high-density straw cluster detectors, the proposed design meets both neutron and gamma response government requirements for backpack monitors.

The dwindling supply of 3He has necessitated the adoption of new technologies for detection of neutrons especially in Homeland Security (HS), where detectors require large volumes of the precious gas. The boron-coated straw (BCS) technology consists of very thin-walled metal tubes equipped with a highly robust coating of 10B4C on the inner wall. The coating, applied with Physical Vapor Deposition (PVD), is atomically bound to the metal substrate, and it is able to resist delamination over a temperature range from -200° C to 1000° C. Accelerated lifetime testing of sealed straw detectors over extreme temperature ranges (-70° C to +125° C) have recently demonstrated a 99% expected lifetime of 30 years. At the same time, the coating purity is high, with a 10B content approaching 77%. Straws stacked 5 deep in a dense array have demonstrated an efficiency of > 70% when evaluated in a cold neutron beam. A number of field worthy HS detectors have been developed over the past 2 years based on the BCS. Examples are presented, including neutron modules for Radiation Portal Monitors (RPM), a vehicle mounted modular detector with an intrinsic efficiency of 30% for unmoderated 252Cf neutrons, and handheld detectors. All of these systems have been government tested. The 10B4C coated straw offers a highly versatile, robust and low cost technology meeting multiple needs in homeland and international security.

The boron-coated straw (BCS) neutron detection technology has been proposed as an attractive 3He replacement solution in a series of applications in homeland security, neutron science, and safeguards. In order to improve the neutron detection efficiency of the BCS, while maintaining manufacturability, Proportional Technologies, Inc. is introducing a modified BCS with significant performance benefits. The proposed pie-like shape consists of any desired number of arc segments, and an equal number of septa walls, which are radially oriented, and extending a desired distance towards the center of the geometry. Each septum is essentially a segment of the wall that has been collapsed onto itself, resulting in a rigid surface, coated on both sides. The area coated on the septa is added to the area coated on the arc segments, thus offering a significant benefit in sensitivity. Compared to a round straw of the same diameter, the coated wall area of the proposed shape with 12 septa is 3 times larger, assuming the septa are equal in length to each of the arc segments. We present laboratory measurements with two prototype detectors that demonstrate stable operation, a neutron sensitivity that is nearly 3 times higher than that measured in a simple BCS with no septa walls, and adequate energy resolution to effectively discriminate against gamma rays.

In previous projects funded by the DOE, Proportional Technologies, Inc. developed the basic design of a neutron imaging detector, based on the boron-coated straw technology, aimed to replace 3He tubes in large-scale neutron science instruments. Recent efforts have focused on automated production methods, including a critical 10B 4 C high volume sputter coating system, and automated in-line straw tube production system, in order to dramatically increase production capacity and reduce cost. A limited-scale prototype developed during Phase I of the project was operated successfully in the Cold Neutron Chopper Spectrometer (CNCS) at the SNS (ORNL) over a period of 6 months, for more than 2500 hours logging more than 200 million events. The prototype demonstrated longitudinal spatial resolution of 5.5 mm (FWHM), and good image uniformity (2%). A 5-layer deep, fully operational, imaging panel has been completed recently. The panel was installed in the CNCS instrument, and tested in real neutron scattering experiments. Results of detection efficiency over a range of neutron wavelengths, image uniformity, and time-of-flight distribution are reported.

Proposed Diagnostic and Statistical Manual (DSM) of Mental Disorders, fifth edition (DSM-5), substance use disorder (SUD) criteria (www.dsm5.org) would involve more change for nicotine, compared to other drug classes in DSM-IV (1–3). Specifically, proposed DSM-5 nicotine use disorder (NUD) criteria would increase the number of criteria used for diagnosis from 7 to 11, with the addition of three DSM-IV abuse criteria (used for most other substances in DSM-IV with the exception of nicotine), and a new Craving criterion. In addition, the threshold for nicotine diagnosis would be lowered from 3 to 2 symptoms. The implications of proposed changes to NUD criteria with regard to the prevalence and validity of nicotine diagnoses, and diagnostic concordance across iterations of DSM warrant study prior to the publication of DSM-5 in 2013. DSM-IV recognizes two SUDs: substance abuse and dependence. A diagnosis of substance abuse requires 1 of 4 criteria representing certain negative consequences resulting from substance use: recurrent failure to meet Role Obligations, Hazardous Use, Interpersonal Problems, and Legal Problems. DSM-IV substance dependence requires the co-occurrence of 3 of 7 criteria within 1-year: Tolerance, Withdrawal, use more or longer than intended (Larger/Longer), failed attempts or strong desire to limit use (Quit/Cut), Much Time spent using, Reduce Activities in order to use, and psychological or physical problems exacerbated or caused by use (Psych/Phys). Importantly, DSM-IV acknowledges that some of the generic dependence criteria used to determine a nicotine diagnosis do not appear to directly apply to nicotine or require some explanation as to how they might apply to nicotine (2: page 243; 3: page 264). Proposed DSM-5 NUD criteria include 11 symptoms (1): 3 DSM-IV abuse criteria (i.e., Role Obligations, Hazardous Use, Interpersonal Problems), all 7 DSM-IV dependence criteria, and a new Craving symptom (i.e., strong desire to engage in use). Proposed DSM-5 NUD requires the co-occurrence of two or more of 11 symptoms within 1-year. Presence of 2–3 symptoms represents “moderate” NUD, and 4 or more symptoms represents “severe” NUD. The use of a criterion set that combines abuse and dependence symptoms in DSM-5 is based on the idea that the proposed criteria represent a single dimension, which has been supported for alcohol and some other drugs (e.g., 4, 5, 6). To date, only 1 study has examined the dimensionality of proposed DSM-5 NUD criteria (7), and like other studies of nicotine-related symptoms (e.g., 8, 9), found support for a single dimension. Because few existing datasets include data relevant to examining proposed DSM-5 NUD criteria, we attempted to replicate (cf. 7) the dimensionality and performance characteristics of 10 of the 11 (Role Obligation not assessed) proposed DSM-5 NUD criteria. Decisions to include new diagnostic criteria, such as Craving, need to consider whether the criteria improve diagnosis in terms of reliability, validity, and case identification (10). This study examined concordance of DSM-IV dependence and proposed DSM-5 NUD, and evidence for concurrent validity of the two algorithms in adolescents and young adults, who were initially recruited from substance use treatment. This study addresses the DSM-5 workgroup’s call for field trials in patient samples because patient samples tend to have more, and more severe symptoms, compared to the general population (1). We focus on adolescents and young adults because nicotine addiction often has origins in adolescence, and peak rates of tobacco use emerge in young adulthood (11). For analyses comparing the prevalence of DSM-IV dependence and proposed DSM-5 NUD, we predicted greater prevalence of proposed DSM-5 NUD compared to DSM-IV, due to proposed DSM-5’s lower threshold and expanded array of symptoms. We also predicted that lowering the threshold to 2 symptoms would result in limited concurrent validity for proposed DSM-5 NUD, relative to DSM-IV nicotine dependence. We tested the unidimensionality of proposed DSM-5 NUD criteria, and used Item Response Theory (IRT) to examine symptom performance characteristics. We predicted that the 3 DSM-IV abuse items would show poor psychometric performance (e.g., low rates of endorsement) when included in the proposed DSM-5 algorithm.

The authors compared 3 measures of readiness to change alcohol use commonly used in clinical research and practice with adolescents: the Readiness Ruler, the SOCRATES (subscales of Recognition and Taking Steps), and a Staging Algorithm. The analysis sample consisted of 161 male and female adolescents presenting for intensive outpatient alcohol-abuse treatment who reported current alcohol use at the initial assessment. Evidence for concurrent validity was assessed by computing simple correlations of each readiness measure with the other 3 and of each readiness measure with drinking behavior (percentage of days abstinent [PDA] and drinks per drinking day [DDD], respectively, in the last 30 days) at the start of treatment and at the 6-month follow-up assessment. Evidence for predictive validity was based on percentage of independent variance accounted for by each of the readiness measures in predicting drinking behavior at 6 months from the start of treatment, and then in predicting drinking behavior at 12 months from the readiness assessment at 6 months. The results showed that all but Recognition had good concurrent validity, the Readiness Ruler score showed consistent evidence for predictive validity, and the Staging Algorithm showed good predictive validity for DDD at 6 and 12 months. For the 82 participants with an alcohol-use disorder diagnosis, the findings for the Ruler and Recognition were similar, but the Staging Algorithm had poorer prediction of DDD at 12 months, and Taking Steps was a better predictor of 6- and 12-month PDA and DDD. Research and clinical implications of the findings are discussed.

US and international government efforts to equip major seaports with large area neutron detectors, aimed to intercept the smuggling of nuclear materials, have precipitated a critical shortage of 3 He gas. It is estimated that the annual demand of 3 He for US security applications alone is more than the worldwide supply. This is strongly limiting the prospects of neutron science, safeguards, and other applications that rely heavily on 3 He-based detectors. Clearly, alternate neutron detection technologies that can support large sensitive areas, and have low gamma sensitivity and low cost must be developed. We propose a low-cost technology based on long copper tubes (straws), coated on the inside with a thin layer of 10 B-enriched boron carbide ( 10 B 4 C). In addition to the high abundance of boron on Earth and low cost of 10 B enrichment, the boron-coated straw (BCS) detector offers distinct advantages over conventional 3 He-based detectors, and alternate technologies such as 10 BF 3 tubes and 10 B-coated rigid tubes. These include better distribution inside moderator assemblies, many-times faster electronic signals, no pressurization, improved gamma-ray rejection, no toxic or flammable gases, and ease of serviceability. We present the performance of BCS detectors dispersed in a solid plastic moderator to address the need for portal monitoring. The design adopts the outer dimensions of currently deployed 3 He-based monitors, but takes advantage of the small BCS diameter to achieve a more uniform distribution of neutron converter throughout the moderating material. We show that approximately 63 BCS detectors, each 205 cm long, distributed inside the moderator, can match or exceed the detection efficiency of typical monitors fitted with a 5 cm diameter 3 He tube, 187 cm long, pressurized to 3 atm.

This study examined the concurrent and predictive validity of four brief measures of readiness to change tobacco use for use with adolescents in clinical practice (Readiness Ruler, Thoughts About Abstinence, motivation to abstain, and confidence to abstain) and a single-item measure of difficulty to abstain. Participants were 154 adolescent smokers recruited from outpatient addictions treatment, who completed assessments shortly after admission and at 6- and 12-month follow-up. Concurrent validity analyses indicated that the four readiness measures were moderately correlated at each time point. Predictive validity analyses indicated that the Ruler and the motivation to abstain ratings predicted number of cigarettes smoked at 6 and 12 months. Perceived difficulty to abstain predicted cigarette use over and above the readiness to change measures. Results support the clinical utility of the Ruler and motivation to abstain as brief measures of readiness to change, and perceived difficulty to abstain as a tool to aid adolescent tobacco cessation.

The measurement of readiness to change has become common practice in alcohol and drug treatment of both adults and adolescents. Nevertheless, there is relatively little research on the validity of measures of readiness to change among treated adolescents. The purpose of this study was to compare three measures of readiness to change marijuana use commonly used in clinical research and practice with adolescents: the Readiness Ruler, the Stages of Change Readiness and Treatment Eagerness Scale (SOCRATES; Factors 1 and 2, Recognition and Taking Steps, respectively), and a staging algorithm.The participants were 174 adolescents presenting for intensive outpatient alcohol and drug treatment who reported current marijuana use at the initial assessment. Evidence for concurrent validity was assessed by computing simple correlations among readiness measures, and correlations of each readiness measure with marijuana involvement (percentage of days abstinent in the last 30 days, problem severity score, and marijuana abuse and dependence symptom count [based on Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, criteria]) at both the initial/baseline assessment and at a 6-month follow-up assessment. Evidence for predictive validity was based on the results of multilevel regression models of the readiness measures in predicting frequency of marijuana use, symptoms, and problems at 6 months from the initial readiness assessment and then in predicting marijuana use, symptoms, and problems at 12 months from the readiness assessment at 6 months.The results showed evidence for good concurrent and predictive validity for the ruler, the staging algorithm, and Taking Steps but poor evidence for the validity of Recognition. The ruler emerged as the measure with the most clinical utility when brevity and ease of administration are taken into account.Research and clinical implications of the findings are discussed.

Aims Controversy exists regarding the inclusion of cannabis withdrawal as an indicator of dependence in the next revision of the Diagnostic and Statistical Manual of Mental Disorders (DSM) and International Classification of Diseases (ICD). This study contrasted the concurrent and predictive validity of three operational definitions of cannabis withdrawal in a sample of treated adolescents. Design Prospective study of treated adolescents with 1-year follow-up. Setting and participants Adolescents (n = 214) were recruited from intensive out-patient treatment programs for substance abuse, and followed at 1 year (92% retention). Youth who were included in the analyses reported regular cannabis use. Measurements The number of DSM-IV cannabis abuse and dependence symptoms at baseline and 1-year follow-up, past year frequency of cannabis use at baseline and follow-up, and periods of abstinence at 1-year follow-up. Cannabis withdrawal was defined based on (i) the presence of two or more cannabis withdrawal symptoms; (ii) a definition proposed by Budney and colleagues (2006) that requires four or more withdrawal symptoms (foursymptom definition); and (iii) the use of latent class analysis to identify subgroups with similar cannabis withdrawal symptom profiles. Findings and conclusions All three definitions of cannabis withdrawal demonstrated some concurrent validity. Only the four-symptom and latent class-derived definitions of withdrawal predicted severity of cannabis-relatedproblemsat1-yearfollow-up.Nocannabiswithdrawaldefinitionpredictedfrequencyof useatfollowup. Further research is needed to determine the clinical utility and validity of the four-symptom definition, as well as alternative definitions of cannabis withdrawal, to inform revisions leading to DSM-V and ICD-11.

OBJECTIVE: To examine the National Institute on Alcohol Abuse and Alcoholism Youth Guide alcohol frequency screening thresholds when applied to Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5) diagnostic criteria, and to describe alcohol use patterns and alcohol use disorder (AUD) characteristics in rural youth from primary care settings. STUDY DESIGN: Adolescents (n = 1193; ages 12 through 20 years) visiting their primary care practitioner for outpatient visits in six rural primary care clinics were assessed prior to their practitioner visit. A tablet computer collected youth self-report of past-year frequency and quantity of alcohol use and DSM-5 AUD symptoms. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were determined. RESULTS: For early adolescents (ages 12 through 14 years), 1.9% met DSM-5 criteria for past-year AUD and ≥3 days with alcohol use in the past year yielded a screen for DSM-5 with optimal psychometric properties (sensitivity: 89%; specificity: 95%; PPV: 37%; NPV: 100%). For middle adolescents (ages 15 through 17 years), 9.5% met DSM-5 AUD criteria, and ≥3 past year drinking days showed optimal screening results (sensitivity: 91%; specificity: 89%; PPV: 50%; NPV: 99%). For late adolescents (ages 18 through 20 years), 10.0% met DSM-5 AUD criteria, and ≥12 past year drinking days showed optimal screening results (sensitivity: 92%; specificity: 75%; PPV: 31%; NPV: 99%). The age stratified National Institute on Alcohol Abuse and Alcoholism frequency thresholds also produced effective results. CONCLUSION: In rural primary care clinics, 10% of youth over age 14 years had a past-year DSM-5 AUD. These at-risk adolescents can be identified with a single question on alcohol use frequency.Copyright © 2016 Elsevier Inc. All rights reserved. Language: en

Most adolescent cannabis use occurs in social settings among peers. Solitary cannabis use during adolescence may represent an informative divergence from normative behavior with important implications for understanding risk for cannabis problems. This longitudinal study examined associations of adolescent solitary cannabis use with levels of cannabis use and problems in adolescence and in young adulthood.Cannabis using-adolescents aged 12-18 were recruited from clinical programs (n=354; 43.8% female; 83.3% Caucasian) and community sources (n=93; 52.7% female; 80.6% Caucasian). Participants reported on cannabis use patterns and diagnostic symptoms at baseline and multiple follow-ups into young adulthood.Compared to social-only users, adolescent solitary cannabis users were more likely to be male and reported more frequent cannabis use and more DSM-IV cannabis use disorder (CUD) symptoms. Regression analyses showed that solitary cannabis use in adolescence predicted CUD symptom counts in young adulthood (age 25) after controlling for demographic variables and the frequency of adolescent cannabis use. However, solitary adolescent cannabis use was no longer predictive of age 25 CUD symptoms after additionally controlling for adolescent CUD symptoms.Solitary cannabis use is associated with greater cannabis use and problems during adolescence, but evidence is mixed that it predicts young adult cannabis problems.

Objective The present investigation had two main goals: (1) Determine whether binary substance use disorder (SUD) diagnoses are indicators of a unidimensional trait indexing severity of disorder; and, (2) demonstrate the predictive, concurrent and construct validity of the SUD severity scale. Methods Boys and their biological parents were administered structured diagnostic interviews to diagnose SUD. Item response theory (IRT) was applied to determine whether the diagnoses are indicators of a unidimensional trait. The score on this scale was correlated with substance use behavior, violence, treatment history, risky sex, and social adjustment. Results SUD diagnoses are indicators of a unidimensional latent trait. Maternal and paternal SUD severity predicted son's SUD severity at age 19. The score on the SUD severity scale correlated with drug use frequency, number of different drugs used in lifetime, treatment seeking, illegal behavior, social maladjustment, and risky sex. Conclusion SUD can be quantified on an interval scale indexing severity of disorder. The advantages of measuring SUD severity as a continuous trait are discussed.

This article presents the proceedings of a symposium held at the June 2005 meeting of the Research Society on Alcoholism in Santa Barbara, California. Impaired control over substance use has long been considered a central feature of alcohol and drug dependence. However, much remains to be learned about the nature of impaired control, the mechanisms by which acute and chronic substance use can lead to impaired control, and how this construct is best assessed in the laboratory and the clinic. The goal of this symposium was to describe current perspectives on impaired control over alcohol and drug use from diverse research areas, to promote future multidisciplinary work in this area. Four speakers described their work on impaired control using human clinical samples (Dr. Chung), animal models (Dr. Miczek), experimental laboratory paradigms in humans (Dr. Fillmore), and neuroimaging studies (Dr. Easdon). Taken together, the talks highlighted the heterogeneous nature of constructs such as impaired inhibitory control, and patterns of impulsive and compulsive substance use. Future clinical and experimental research should attempt to carefully define and measure particular aspects of impaired control and to seek insights from other disciplines.

This article presents a novel method for measuring the acute effects of alcohol. One hundred twenty nonproblem drinkers aged 21-28 participated in 3 alcohol administration sessions that produced peak blood alcohol concentrations (BACs) near .09 g%. Subjective intoxication ratings were taken at multiple points across rising and falling BACs. Mathematical modeling techniques decomposed intoxication ratings into a tonic component sensitive to BAC level and a phasic component sensitive to BAC rate of change. This model provided a good fit to observed data. Tonic and phasic gain parameters showed high repeatability across sessions. The average phasic gain parameter was about 4 times larger than the average tonic gain parameter, indicating that subjective intoxication is usually more affected by BAC change than by BAC level. The associations of drinking practices with tonic and phasic gain parameters varied by gender and family history of alcoholism. Tonic-phasic modeling allows individual and group differences in the acute effects of alcohol to be studied as time-dynamic processes.

This study examined the latent class structure of Diagnostic and Statistical Manual of Mental Disorders (text rev.; DSM-IV; American Psychiatric Association, 2000) symptoms used to diagnose cannabis, hallucinogen, cocaine, and opiate disorders among 501 adolescents recruited from addictions treatment. Latent class results were compared with the DSM-IV categories of abuse and dependence, and latent transition analysis (LTA) was used to examine changes in symptom severity over a 1-year follow-up. Although 2- and 3-class solutions provided the best fit to the data (2-class: hallucinogens, cocaine, opioids; 3-class: cannabis), 3-class solutions provided more substantive results and were emphasized in analyses. There was good agreement between latent classes and DSM-IV diagnosis. LTA suggested greater likelihood of transitioning to a less severe class at 1 year for all 4 drugs; in- and outpatients differed in pattern of change.

Objective: DSM-IV alcohol dependence criteria of tolerance to alcohol and drinking more or longer than intended have relatively high prevalence among youth, and may be vulnerable to false positive symptom assignments that degrade diagnostic validity. We conducted a methodological study of DSM-IV symptom queries used to assess alcohol tolerance and impaired control over drinking to determine potential sources of measurement error. Method: Adolescents recruited from addictions treatment participated in either a focus group (n = 9) or an individual interview (n = 41) to provide data on their interpretation of selected items contained in a semi-structured diagnostic interview. Results: When alcohol tolerance is operationally defined as a change in quantity to obtain the same effect, large individual differences in the change in quantity that represents a high level of tolerance limit the utility of this operational definition as an indicator of dependence. The symptom “drinking more or longer than intended”, includes the embedded assumption that a limit on use had been set. Teens, however, typically intended to become intoxicated, rather than to keep to a limit. Conclusions: Adolescents’ understanding of symptom queries suggests how validity of DSM-IV alcohol symptoms and diagnoses can be improved through greater attention to developmental considerations affecting assessment.

Item response theory (IRT) is supplanting classical test theory as the basis for measures development. This study demonstrated the utility of IRT for evaluating DSM-IV diagnostic criteria. Data on alcohol, cannabis, and cocaine symptoms from 372 adult clinical participants interviewed with the Composite International Diagnostic Interview--Expanded Substance Abuse Module (CIDI-SAM) were analyzed with Mplus (B. Muthen & L. Muthen, 1998) and MULTILOG (D. Thissen, 1991) software. Tolerance and legal problems criteria were dropped because of poor fit with a unidimensional model. Item response curves, test information curves, and testing of variously constrained models suggested that DSM-IV criteria in the CIDI-SAM discriminate between only impaired and less impaired cases and may not be useful to scale case severity. IRT can be used to study the construct validity of DSM-IV diagnoses and to identify diagnostic criteria with poor performance.

Beyond the initial relapse episode, little is known about short-term patterns of alcohol and other drug use in treated adolescents. This study characterized treated teens' short-term alcohol and other drug use trajectories over 1-year follow-up.Adolescents (N = 110, ages 12-18, 65% male, 94% white) recruited from addictions treatment, with a current DSM-IV alcohol diagnosis, reported on daily alcohol and other drug use in monthly telephone contacts over 1-year follow-up using the Timeline Follow-Back procedure. Latent class mixture modeling identified trajectories based on maximum number of consecutive abstinent days per month, separately for alcohol and other drugs.Four alcohol trajectories were identified: high abstinence (53%), decreasing abstinence (10%), increasing abstinence (16%) and low abstinence (21%). The alcohol trajectories were distinguished by gender, age, readiness to change substance use and alcohol-related coping. To characterize changes in alcohol abstinence in relation to abstinence from other drugs, four other drug trajectories were identified: high (59%), decreasing (12%), increasing (14%) and low (15%) abstinence. Cross-classification of the alcohol and drug trajectories indicated a moderate level of concordance (kappa = 0.49).Multiple pathways of short-term change in alcohol and other drug use were identified. Although changes in abstinence from alcohol and other drug use tended to co-occur, exceptions were observed. Differences between alcohol trajectories in readiness to change substance use and use of substance coping suggest the potentially positive impact of targeted and effectively timed interventions that focus on motivational enhancement and on improving substance coping for certain adolescent subgroups.