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Although a large number of crystal structures of heterocyclic thiosemicarbazones have recently appeared in the literature, few structures of heterocyclic bis(thiosemicarbazones) or their metal complexes have been reported. Complexes of iron(II), indium(III), tin(IV), bismuth(III) involve bis(thiosemicarbazones) coordinating as N3S2 pentadentate ligands, often resulting in 7-coordinate complexes. In contrast, complexes with zinc(II) are often binuclear with thiosemicarbazone moieties of a bis(thiosemicarbazone) coordinating to two different zinc centers. Also included in this study is the structure of the first complex with a 2,6-diformylpyridine bis(thiosemicarbazone) ligand, a 4-coordinate nickel(II) complex with unusual coordination.

The goal of this study is to develop and validate a lightweight, interpretable machine learning (ML) classifier to identify opioid overdoses in emergency medical services (EMS) records. We conducted a comparative assessment of three feature engineering approaches designed for use with unstructured narrative data. Opioid overdose annotations were provided by two harm reduction paramedics and two supporting annotators trained to reliably match expert annotations. Candidate feature engineering techniques included term frequency-inverse document frequency (TF-IDF), a highly performant approach to concept vectorization, and a custom approach based on the count of empirically-identified keywords. Each feature set was trained using four model architectures: generalized linear model (GLM), Naïve Bayes, neural network, and Extreme Gradient Boost (XGBoost). Ensembles of trained models were also evaluated. The custom feature models were also assessed for variable importance to aid interpretation. Models trained using TF-IDF feature engineering ranged from AUROC = 0.59 (95% CI: 0.53-0.66) for the Naïve Bayes to AUROC = 0.76 (95% CI: 0.71-0.81) for the neural network. Models trained using concept vectorization features ranged from AUROC = 0.83 (95% 0.78-0.88)for the Naïve Bayes to AUROC = 0.89 (95% CI: 0.85-0.94) for the ensemble. Models trained using custom features were the most performant, with benchmarks ranging from AUROC = 0.92 (95% CI: 0.88-0.95) with the GLM to 0.93 (95% CI: 0.90-0.96) for the ensemble. The custom features model achieved positive predictive values (PPV) ranging for 80 to 100%, which represent substantial improvements over previously published EMS encounter opioid overdose classifiers. The application of this approach to county EMS data can productively inform local and targeted harm reduction initiatives., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Graham et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Background: Unprecedented increases in substance-related overdose fatalities have been observed in Texas and the U.S. since the onset of the COVID-19 pandemic and have made clear there is considerable need to reduce harms associated with drug use. At the federal level, initiatives have called for widespread dissemination and implementation of evidence-based harm reduction practices to reduce overdose deaths. Implementation of harm reduction strategies is challenging in Texas. There is a paucity of literature on understanding current harm reduction practices in Texas. As such, this qualitative study aims to understand harm reduction practices among people who use drugs (PWUD), harm reductionists, and emergency responders across four counties in Texas. This work would inform future efforts to scale and spread harm reduction in Texas., Methods: Semi-structured qualitative interviews were conducted with N = 69 key stakeholders (25 harm reductionists; 24 PWUD; 20 emergency responders). Interviews were transcribed verbatim, coded for emergent themes, and analyzed using Applied Thematic Analysis with Nvivo 12. A community advisory board defined the research questions, reviewed the emergent themes, and assisted with interpretation of the data., Results: Emergent themes highlighted barriers to harm reduction at micro and macro levels, from the individual experience of PWUD and harm reductionists to systemic issues in healthcare and the emergency medical response system. Specifically, (1) Texas has existing strengths in overdose prevention and response efforts on which to build, (2) PWUD are fearful of interacting with healthcare and 911 systems, (3) harm reductionists are in increasing need of support for reaching all PWUD communities, and (4) state-level policies may hinder widespread implementation and adoption of evidence-based harm reduction practices., Conclusions: Perspectives from harm reduction stakeholders highlighted existing strengths, avenues for improvement, and specific barriers that currently exist to harm reduction practices in Texas., (© 2023. The Author(s).)

Background: Drug overdose deaths in Texas have been accelerating in recent years with an increase of 33% in the 12 months leading up to December 2020. Accurate counts of nonfatal overdoses - including associated aspects of overdose, such as substances involved, demographic information, and reversal agents administered is critical to increase timely and adequate response to individuals and communities in need. Methods: Twenty semi-structured interviews were conducted with harm reduction workers across four Texas counties to understand existing methods of reporting overdoses, naloxone dissemination/administration, and recommendations for improving overdose surveillance. Interviews were transcribed and emergent themes were identified based on the a priori research goals. Results: Findings highlighted a variety of overdose data collection methods and tools among harm reduction organizations including Excel spreadsheet, web-based TONI application, notes on personal cell phones, and paper notes. Types of overdose data collected varied widely. Participants noted existing methods are suboptimal and that there is a need for a unified, statewide reporting system to improve overdose data capture. Participants also highlighted that overdose surveillance should include "hidden populations" of people who use drugs that are not currently counted in surveillance methods as a result of not interacting with the healthcare system. Conclusions: Texas lacks a unified overdose reporting system to capture critical data to inform overdose response and prevention efforts. Nontraditional reporters may be critical toward improving overdose syndromic efforts and capturing data among hard-to-reach populations. Harm reduction organizations are uniquely positioned to facilitate reporting among community gatekeepers and people who use drugs.

HIV and substance use interact synergistically to exacerbate disease progression and contribute to poorer engagement in treatment. There is a lack of qualitative research exploring the complexity of systems that impact HIV patients' linkage to and retention in both substance use and HIV care. Data from qualitative individual interviews with 16 HIV and 13 substance use providers were analyzed using applied thematic analysis. Four themes emerged as barriers to linkage to care providers limited knowledge with appropriate referrals; limited access to treatment options within the community; difficult admission criteria to substance use facilities; and communication challenges across providers including power differential. Emergent themes as barriers to treatment retention were: unstable life of people who use drugs; providers' negative attitude and stigma towards patients; and transportation challenges. Interventions are needed to increase provider cross-training in HIV and substance use disorders, reduce barriers to accessing treatment, and improve communication across providers are needed.

Background: People with double burden of HIV and substance use have poorer treatment engagement and worse treatment outcomes. Cross-training of HIV and substance use disorder clinicians can potentially enhance the scale up and quality of integrated care. Research is needed on clinicians' areas of greatest training need in order to inform training development., Methods: Data from semi-structured individual interviews with 16 HIV and 13 substance use disorder clinicians (N = 29) examining clinician perspectives on their training needs were analyzed using thematic analysis focused on both a priori and emergent subthemes., Results: Several key emergent subthemes were identified across the a priori themes of: 1) past training experiences; 2) gaps in training; and 3) training and supervision format/structure. Both HIV and substance use clinicians reported they had received minimal formal cross-training and had mostly been trained "on the job." Clinicians also emphasized gaps in training regarding sensitivity and anti-stigma, the latest medications for opioid use disorder, and HIV prevention/treatment and referral resources. Regarding training and supervision format, clinicians cited didactic workshops and ongoing supervision as appealing strategies., Conclusions: Results show that lack of formal and updated training for clinicians is an important gap in providing integrated HIV and substance use treatment. Didactic workshops and ongoing support strategies that address stigma, medications for HIV and substance use disorder, and referral resources are likely to be particularly valuable., (© 2022. The Author(s).)

The overdose crisis in the USA remains a growing and urgent public health concern. Over 108,000 people died due to overdose during 2021. Fatal and non-fatal overdoses are under-reported in the USA due to current surveillance methods. Systemic gaps in overdose data limit the opportunity for data-driven prevention efforts and resource allocation. This study aims to improve overdose surveillance and community response through developing a digital platform for overdose reporting and response among harm reduction organizations. We used a community-engaged, user-center design research approach. We conducted qualitative interviews with N = 44 overdose stakeholders including people who use drugs and harm reductionists. Results highlighted the need for a unified, multilingual reporting system uniquely tailored for harm reduction organizations. Anonymity, data transparency, protection from legal repercussions, data accuracy, and community-branded marketing emerged as key themes for the overdose platform. Emergent themes included the need for real-time data in a dashboard designed for community response and tailored to first responders and harm reduction organizations. This formative study provides the groundwork for improving overdose surveillance and data-driven response through the development of an innovative overdose digital platform., (© 2022. The Author(s).)

Objective: The objective of this study is to assess the differences in buprenorphine prescribers from a county level in the state of Texas by comparing the Substance Abuse and Mental Health Services Administration (SAMHSA) Buprenorphine Practitioner Locator to the Drug Enforcement Administration's (DEA) Controlled Substance Act (CSA) database., Methods: County-level counts of buprenorphine prescribers were calculated from both the publicly available SAMHSA buprenorphine practitioner locator list and the DEA CSA database. These were then used to estimate the number of providers per 100,000 residents in each county. Regional variation in access to buprenorphine was compared descriptively across the state using poverty data from the US Census and county-level demography from the Texas Demographic Center., Results: This study found 68.8% more X-waivered providers on the DEA CSA database (n = 2,622) with at least one provider reported in 125 of 144 counties in the state (49.2%) compared to the SAMHSA Buprenorphine Practitioner Locator (n = 1,553) with at least one provider reported in 103 counties (40.5%)., Conclusions: The lack of a complete public registry of buprenorphine prescribers can inhibit the ability of patients to identify a convenient treatment. More work is needed to quantify the gap between treatment capacity and treatment need.

Accelerating ecosystem degradation has spurred proposals to vastly expand the extent of protected areas (PAs), potentially affecting the livelihoods and well-being of indigenous peoples and local communities (IPLCs) worldwide. The benefits of multiuse PAs that elevate the role of IPLCs in management have long been recognized. However, quantitative examinations of how resource governance and the distribution of management rights affect conservation outcomes are vital for long-term sustainability. Here, we use a long-term, quasi-experimental monitoring dataset from four Indonesian marine PAs that demonstrates that multiuse PAs can increase fish biomass, but incorporating multiple governance principles into management regimes and enforcing rules equitably are critical to achieve ecological benefits. Furthermore, we show that PAs predicated primarily on enforcing penalties can be less effective than those where IPLCs have the capacity to engage in management. Our results suggest that well-governed multiuse PAs can achieve conservation objectives without undermining the rights of IPLCs.

Although parent training (PT) interventions are considered the gold standard for preventing externalizing behaviors in children and youth, their dissemination in low-income Latina/o immigrant communities continues to be scarce throughout the United States (US). An alternative to address this gap in service delivery consists of implementing culturally adapted PT interventions characterized by cultural and contextual relevance. Thus, the main objective of this qualitative study was to document salient immigration-related experiences, as well as parenting needs and challenges, as reported by 30 low-income Mexican-origin immigrant caregivers residing in an urban setting in the Southern United States. The research methodology was guided by the tenets of the Thematic Analysis approach, which involved collecting data through a series of focus group interviews. Qualitative research findings highlight the importance of culturally and contextually tailoring adapted PT prevention interventions, prior to their delivery in contexts that differ from those in which interventions were originally adapted. Specifically, parents in the current investigation provided detailed accounts of immigration-related stressors that are highly relevant to inform recruitment procedures, intervention curriculum, and intervention delivery activities., (© 2020 Family Process Institute.)

Background: An understanding of patient and clinician opinions about remote video musculoskeletal consultations might help determine how to increase appeal and utilization. The purpose of this study was to evaluate perceptions of remote video musculoskeletal consultations. Our research questions was what are patient and clinician facilitators and barriers for the use of remote video consultations?, Methods: Prior to the COVID-19 pandemic 27 English speaking adult patients seeking ambulatory care for a musculoskeletal problem, and 10 English-speaking musculoskeletal clinicians were interviewed using a guide. Interviews were audio-recorded, transcribed, and coded using applied thematic analysis., Results: Patient and clinician incentives for remote video consultations included increased convenience, lower costs, less waiting time, and a better experience. Patient and clinician barriers to remote video consultations included concerns about familiarity with technology, lack of personal interaction and physical examination, inability to perform procedures, difficulties with reimbursement (clinicians), as well as technical, logistical, and privacy issues., Conclusion: This qualitative study performed prior to the pandemic found that adoption of remote video consultation for musculoskeletal problems may improve with seamless, efficient, and effective care, at an affordable price, particularly if the human connection is similar to what occurs in person.

Introduction: Strategies for pain alleviation have relied heavily on opioids in the recent decades. One consequence is a crisis of opioid misuse, overdose, and overdose related death. This study sought patient and clinician incentives and barriers to the use of opioids in musculoskeletal illness., Methods: In this qualitative study, twenty-eight patients and eight clinicians participated in a semi-structured interview seeking incentives and barriers for opioid use and prescription in musculoskeletal illness. Interviews were conducted by a trained qualitative interviewer. The interview data were transcribed and analyzed using a thematic analysis framework., Results: Patient incentives for opioid use included doctor's orders, opioids being the only effective way to alleviate pain, alleviating symptoms of depression and anxiety, being able to keep a job, and lower cost of opioids relative to alternative treatment options. Patient barriers included associated risks (side effects, addiction) and wanting to control pain intensity. Clinician incentives for prescribing opioids included adequate pain alleviation, patient satisfaction, relatively inexpensive costs of opioids, convenience and doing what was taught by the clinician's superior. Lacking time and resources to adequately inform patients on appropriate opioid use and alternative treatments, likely results in more opioid prescribing than arguably necessary. Barriers for opioid prescribing included specific patient characteristics (psychiatric background, history of opioid misuse) and illness characteristics (nature of the injury, medical contra-indications)., Conclusion: Patients feel that opioids should be used with caution. Clinicians in this study reported a tendency to default to opioids out of habit and convenience. Both patients and clinicians were aware that opioids are often misused to treat emotional pain., (© 2020 Professor P K Surendran Memorial Education Foundation. Published by Elsevier B.V. All rights reserved.)

Background: Chronic pain occurs in up to 85% of persons living with HIV and is commonly treated with long-term opioid therapy (LTOT). We investigated the impact of chronic pain and LTOT on HIV outcomes., Methods: This was prospective cohort study conducted between July 2015 and July 2016 in 5 HIV primary care clinics. Chronic pain was defined as ≥moderate pain for ≥3 months on the Brief Chronic Pain Questionnaire. Chronic pain and LTOT were assessed at an index visit. Suboptimal retention, defined as at least one "no-show" to primary care, and virologic failure were measured over the subsequent year. Multivariable logistic regression models were built for each outcome adjusting for site., Results: Among 2334 participants, 25% had chronic pain, 27% had suboptimal retention, 12% had virologic failure, and 19% were prescribed LTOT. Among individuals not on LTOT, chronic pain was associated with increased odds of suboptimal retention [adjusted odds ratio (aOR) 1.46, 95% confidence interval (CI): 1.10 to 1.93, P = 0.009] and virologic failure (aOR 1.97, 95% CI: 1.39 to 2.80, P < 0.001). Among individuals with chronic pain, there was no association between LTOT and retention, but LTOT was associated with lower rates of virologic failure (aOR 0.56, 95% CI: 0.33 to 0.96, P = 0.03)., Conclusions: Chronic pain in participants not on LTOT was associated with virologic failure. This reinforces the need to identify effective chronic pain treatments for persons living with HIV and investigate their impact on HIV outcomes. The apparent protective association between LTOT and virologic failure in those with pain merits further exploration.

Background: HIV-infected people who use drugs (PWUD) exhibit the highest rates of non-adherence to antiretroviral therapy (ART) among people living with HIV. This contributes to poor treatment outcomes, increased morbidity and mortality, and HIV transmission. However, current interventions fail to address the unique barriers to adherence faced by this population. Life Steps is a brief, single session intervention that demonstrated increased ART adherence among HIV-infected individuals. This study protocol seeks to improve clinical practice by adapting Life Steps for HIV-infected PWUD and adding a brief motivational intervention addressing drug use. This intervention will incorporate educational, motivational, and behavioral skills components specifically aimed at improving adherence and linkage to substance use treatment among HIV-infected PWUD., Methods: This project will consist of three phases using a mixed-methods approach. In Phase 1, qualitative interviews with HIV-infected PWUD and community providers, coupled with feedback from an expert review panel, will be used to enhance the existing Life Steps manual and interventionist training protocol. In Phase 2, the prototype will be pilot tested and qualitative exit interviews with HPWUD will identify the strengths and limitations of the intervention. Data regarding feasibility, acceptability, and barriers to delivery will guide modifications to finalize a modified Life Steps-Drug Use (LS-DU) protocol. In Phase 3, a pilot type 1 hybrid effectiveness-implementation trial will examine the effectiveness of LS-DU relative to a health education intervention control condition on ART adherence and viral load data at 1-, 3-, and 6-months. Data regarding clinic readiness for implementation and intervention sustainability potential will be collected., Discussion: This protocol will adapt and evaluate an intervention to improve adherence among HIV-infected PWUD. Results of this study will provide significant data on the acceptability, initial effectiveness, and sustainability potential of an adherence intervention for a high risk and underserved population. Trial registration NCT02907697.

Treatment regimen fatigue (TRF) is a decreased desire and motivation to maintain vigilance in adhering to treatment, and little is known about TRF in people living with HIV. We aimed to develop a conceptual framework of TRF. Five focus groups were conducted in 2014. Eligible participants were (a) HIV infected, (b) at least 18 years of age, (c) prescribed antiretroviral therapy, and (d) fluent in English. Data were analyzed using thematic analysis. Analyses revealed these themes: patient experiences of TRF; etiological factors at the systems, provider, and patient levels; strategies to manage TRF; consequences of TRF; and protective factors that prevent the occurrence of TRF. The results provided a conceptual framework for future investigations to build on in an effort to improve adherence and retention in HIV care. Study results indicate avenues for intervention at multiple levels (systems, provider, and patient) to reduce treatment burden and improve patient resources and capacity., (Copyright © 2017 Association of Nurses in AIDS Care. Published by Elsevier Inc. All rights reserved.)

Background: There is growing evidence of the negative impact of alcohol on morbidity and mortality of individuals living with HIV but limited evidence of in utero effects of HIV and alcohol on exposure on infants., Methods: We conducted a population-based birth cohort study (N = 667 mother-infant dyads) in South Africa to investigate whether maternal alcohol use and HIV affected gestational outcomes. Descriptive data analysis was conducted for all variables using frequency distributions, measures of central tendency, and estimates of variance. Hierarchical multiple regression was conducted to determine whether maternal alcohol use, maternal HIV status and other risk factors (socioeconomic status, smoking, depression) predicted infant outcomes., Results: Our results showed severity of recent alcohol use and lifetime alcohol use predicted low birth weight. Similarly lifetime alcohol use predicted shorter infant length, smaller head length, smaller head circumference, and early gestational age. However, HIV status was not a significant predictor of gestational outcomes., Conclusions: The unexpected finding that maternal HIV status did not predict any of the gestational outcomes may be due to high rates of ART usage among HIV-infected mothers. The potentially negative effects of HIV on gestational outcomes may have been attenuated by improved maternal health due to high coverage of antiretroviral treatment in South Africa. Interventions are needed to reduce alcohol consumption among pregnant mothers and to support healthy growth and psychosocial development of infants.

Background: People living with HIV (PLWH) with a substance use disorder (SUD) tend to receive inadequate medical care in part because of a siloed healthcare system in which HIV and substance use services are delivered separately. Ideal treatment requires an interdisciplinary, team-based coordinated care approach, but many structural and systemic barriers impede the integration of HIV and SUD services. The current protocol describes the development and preliminary evaluation of a care coordination intervention (CCI), consisting of a tablet-based mobile platform for HIV and SUD treatment providers, an interagency communication protocol, and a training protocol. We hypothesize that HIV and SUD treatment providers will find the CCI to be acceptable, and that after receipt of the CCI, providers will: exhibit higher retention in dual care among patients, report increased frequency and quality of communication, and report increased rates of relational coordination., Methods/design: A three phase approach is used to refine and evaluate the CCI. Phase 1 consists of in-depth qualitative interviews with 8 key stakeholders as well as clinical audits of participating HIV and SUD treatment agencies. Phase 2 contains functionality testing of the mobile platform with frontline HIV and SUD treatment providers, followed by refinement of the CCI. Phase 3 consists of a pre-, post-test trial with 30 SUD and 30 HIV treatment providers. Data will be collected at the provider, organization, and patient levels. Providers will complete assessments at baseline, immediately post-training, and at 1-, 3-, and 6-months post-training. Organizational data will be collected at baseline, 1-, 3-, and 6-months post training, while patient data will be collected at baseline and 6-months post training., Discussion: This study will develop and evaluate a CCI consisting of a tablet-based mobile platform for treatment providers, an interagency communication protocol, and a training protocol as a means of improving the integration of care for PLWH who have a SUD. Results have the potential to advance the field by bridging gaps in a fragmented healthcare system, and improving treatment efficiency, work flow, and communication among interdisciplinary providers from different treatment settings., Trial Registration: NCT02906215.

Personalized drinking feedback is an evidence-based and increasingly common way of intervening with high-risk college drinking. This article extends an earlier review by Walters and Neighbors (S. T. Walters & C. Neighbors, 2005, Feedback interventions for college alcohol misuse: What, why, and for whom? Addictive Behaviors, 30, 1168-1182) by reviewing the literature of published studies using personalized feedback as an intervention for heavy drinking among college students. This article updates and extends the original review with a more comprehensive and recent set of 41 studies, most of which were not included in the original article. This article also examines within-subject effect sizes for personalized feedback interventions (PFIs) for high-risk alcohol use and examines the content of PFIs more closely to provide insight on the most essential components that will guide the future development of feedback-based interventions. In general, PFIs appear to be reliably effective at reducing harmful alcohol misuse among college students. Some components are almost universally included (i.e., drinking profile and normative comparison), precluding inferences regarding their unique contribution. Significantly larger effect sizes were observed for interventions that included decisional balance, practical costs, and strategies to limit risks. The present research provides an important empirical foundation for determining the relative contribution of individual components and facets in the efficacy of PFIs., (PsycINFO Database Record (c) 2013 APA, all rights reserved.)

Oriented achiral molecules and crystals with D(2d) symmetry or one of its non-enantiomorphous subgroups, S(4), C(2v), or C(s), can rotate the plane of transmitted polarized light incident in a general direction. This well-established fact of crystal optics is contrary to the teaching of optical activity to students of organic chemistry. This Minireview gives an overview of the measurement and calculation of the chiroptical properties of some achiral compounds and crystals. Methane derivatives with four identical ligands related by reflection symmetry are quintessential optically inactive compounds according to the logic of van't Hoff. Analysis of the optical activity of simple achiral compounds such as H(2)O and NH(3) provides general aspects of chiroptics that are not readily broached when considering chiral compounds exclusively. We show here, through the use of group theoretical arguments, the transformation properties of tensors, and diagrams, why some achiral, acentric compounds are optically active while others are not.

Ab initio molecular orbital calculations of the optical rotatory response of a single oriented water molecule are described. The unique tensor element g(xy) was computed to be -0.047 bohr(3) with CCSD/6-311+G(d,p). A value of -0.033 was obtained with the minimal valence basis that was better suited to parsing the rotatory response among a limited number of excited states. Transition moments were calculated ab initio and qualitatively derived from the wave functions. Rotations were reckoned from the relative dispositions of the transition moments with respect to the wavevectors. In this way, it was possible to intuitively reckon the form of the optical rotation tensor consistent with that from higher levels of theory and to establish which excitations make the most significant contributions.

The optical rotatory power of achiral crystals of achiral pentaerythritol molecules was measured. The maximum rotations were found to be +/-6 degrees /mm. The quantum mechanically computed rotation of pentaerythritol molecules using linear response theory was 6 times larger although the experimental and theoretical tensors were similarly oriented to within 5 degrees .

New developments in optical microscopy are discussed with relevance to the imaging of amyloid plaques that are pathognomonic of a variety of degenerative disorders. We present the results of linear birefringence, linear dichroism, and circular dichroism imaging of Congo red stained plaques ex vivo and in vitro. A new technique for measuring rapid changes in linear anisotropies is introduced. The application of polarimetric imaging as demonstrated here can be extended to broader pathological practice since polarimetric measurements are sensitive to transformations in tissues that are specific disease signatures.

Classical crystal optics has recently undergone a renaissance as developments in optical microscopy and polarimetry, enabled in part by sensitive imaging CCD cameras and personal computers, now permit the analytical separation of various optical effects that are otherwise convolved in polarized light micrographs. In this tutorial review, we review recent developments in the measurement of the principal crystallo-optical quantities including linear birefringence, linear dichroism, circular birefringence, and circular dichroism, as well as new effects in crystal optics encountered in unusual mixed crystals. The new microscopies and polarimetries are applied to problems of crystallographic twinning, phase transformations, stress birefringence, symmetry reduction, and the design of new crystalline materials.

A microscope was constructed for imaging circular dichroism of heterogeneous anisotropic media. To avoid linear biases that are common with electronic circular polarization modulation, we chose a retrogressive solution: mechanical light modulation by rotating a linear polarizer with respect to a quarter wave plate continuously tuned by tilting to the operating wavelength. Our comparatively slow technique succeeds with near-perfect circular input and signal averaging using a CCD camera. We have applied the method to anomalously birefringent crystals of 1,8-dihydroxyanthraquinone that are shown to have intergrown mirror image domains, undetected by X-ray diffraction because the twinning complexity renders differences in anomalous dispersion, already small, unreliable. The origin of the anomalous birefringence and the assignment of the absolute configuration are discussed.