Direct and integrating sampling in terahertz receivers from wafer-scalable InAs nanowires

Terahertz (THz) radiation will play a pivotal role in wireless communications, sensing, spectroscopy and imaging technologies in the decades to come. THz emitters and receivers should thus be simplified in their design and miniaturized to become a commodity. In this work we demonstrate scalable photoconductive THz receivers based on horizontally-grown InAs nanowires (NWs) embedded in a bow-tie antenna that work at room temperature. The NWs provide a short photoconductivity lifetime while conserving high electron mobility. The large surface-to-volume ratio also ensures low dark current and thus low thermal noise, compared to narrow-bandgap bulk devices. By engineering the NW morphology, the NWs exhibit greatly different photoconductivity lifetimes, enabling the receivers to detect THz photons via both direct and integrating sampling modes. The broadband NW receivers are compatible with gating lasers across the entire range of telecom wavelengths (1.2-1.6 μm) and thus are ideal for inexpensive all-optical fibre-based THz time-domain spectroscopy and imaging systems. The devices are deterministically positioned by lithography and thus scalable to the wafer scale, opening the path for a new generation of commercial THz receivers.

The implementation of thermal and UV nanoimprint lithography for selective area epitaxy

Semiconductor nanowires (NWs) in horizontal configuration could provide a path for scalable NW-based devices. Bottom-up large-scale manufacturing of these nanostructures by selective area epitaxy (SAE) relies on precise nanopatterning of various shapes on the growth masks. Electron beam lithography offers an extraordinary accuracy suited for the purpose. However, this technique is not economically viable for large production as it has a low throughput and requires high investment and operational costs. Nanoimprint lithography (NIL) has the potential to reduce fabrication time and costs significantly while requiring less sophisticated equipment. In this work, we utilize both thermal and UV NIL for patterning substrates for SAE, elucidating the advantages and disadvantages of each lithography technique. We demonstrate the epitaxial growth of Ge and GaAs NWs on these substrates, where we observe high-quality mono-crystalline structures. Even though both processes can produce small uniform structures suitable for SAE, our results show that UV NIL proves to be superior and enables reliable and efficient patterning of sub-100 nm mask features at the wafer scale.

From Layer-by-Layer Growth to Nanoridge Formation: Selective Area Epitaxy of GaAs by MOVPE

Selective area epitaxy at the nanoscale enables fabrication of high-quality nanostructures in regular arrays with predefined geometry. Here, we investigate the growth mechanisms of GaAs nanoridges on GaAs (100) substrates in selective area trenches by metal-organic vapor-phase epitaxy (MOVPE). It is found that pre-growth annealing results in the formation of valley-like structures of GaAs with atomic terraces inside the trenches. MOVPE growth of GaAs nanoridges consists of three distinct stages. Filling the trench in the first stage exhibits a step-flow growth behavior. Once the structure grows above the mask surface, it enters the second stage of growth by forming {101} side facets as the (100) flat top facet progressively shrinks. In the third stage, the fully formed nanoridge begins to overgrow onto the mask with a significantly reduced growth rate. We develop a kinetic model that accurately describes the width-dependent evolution of the nanoridge morphology through all three stages. MOVPE growth of fully formed nanoridges takes only about 1 min, which is 60 times faster than in our set of molecular beam epitaxy (MBE) experiments reported recently, and with a more regular, triangular cross-sectional geometry defined solely by the {101} facets. In contrast to MBE, no material loss due to Ga adatom diffusion onto the mask surface is observed in MOVPE until the third stage of growth. These results are useful for the fabrication of GaAs nanoridges of different dimensions on the same substrate for various applications and can be extended to other material systems.

Trapping Layers Prevent Dopant Segregation and Enable Remote Doping of Templated Self-Assembled InGaAs Nanowires

Selective area epitaxy is a promising approach to define nanowire networks for topological quantum computing. However, it is challenging to concurrently engineer nanowire morphology, for carrier confinement, and precision doping, to tune carrier density. We report a strategy to promote Si dopant incorporation and suppress dopant diffusion in remote doped InGaAs nanowires templated by GaAs nanomembrane networks. Growth of a dilute AlGaAs layer following doping of the GaAs nanomembrane induces incorporation of Si that otherwise segregates to the growth surface, enabling precise control of the spacing between the Si donors and the undoped InGaAs channel; a simple model captures the influence of Al on the Si incorporation rate. Finite element modeling confirms that a high electron density is produced in the channel.

1156 IMPROVING RECOGNITION OF POLYPHARMACY AND ADDRESSING INAPPROPRIATE PRESCRIBING ON A CARE OF THE ELDERLY WARD

Introduction

Polypharmacy is an increasing concern in medicine which will lead to prescribing errors, serious drug interactions and potentially inappropriate prescribing.

Aim

To improve recognition of ‘Polypharmacy’, routine medication reviews during patient admissions and better communication and awareness of ‘Polypharmacy’ to General Practitioners (GP).

Methods

This audit consisted of two cycles both performed over 6 weeks.

Inclusion criteria

Patients aged 65 < and on 6 < medications, admitted to Elderly Care ward at Chelsea and Westminster hospital. Interventions after the first cycle included education such as encouragement of clear documentation in medical record and GP summary, introduction of medication reviews as part of ward round, collaborative work with pharmacists. Potentially Inappropriate Medications (PIMS) were assessed using the STOPP/START criteria approved by NICE guidelines for review of medication regimes and highlighting PIMS.

Results

First cycle - 30 patients were recruited with an average age of 79.2 (13 males and 17 females). An average number of PIMS at the time of admission was 1.3 and 0.5 on discharge. Only 1/30 (3.3%) has ‘Polypharmacy’ documented and medication reviewed; Medications Reconciliation was 29/30 (96.7%). None of the patient has documentation for Polypharmacy.

Second cycle - 29 patients were recruited with and average age of 80.1. (7 males and 22 females). PIMs on admission was 1.4 and 0.3 on discharge. 25/29 (86.2%) patients had ‘Polypharmacy being documented and Medication review for 29/29(100%). Medication Reconciliation was 29/29(100%). Most Common PIMS across both cycles were statins, antihypertensive and Proton Pump Inhibitor.

Conclusion

The interventions complete improved significantly the awareness of Polypharmacy. There is a significant increment in number of medication review of 96.7% and 82.9% on documentation for ‘Polypharmacy’, and 20% reductions in PIMS on discharge.

Selective area epitaxy of GaAs: the unintuitive role of feature size and pitch

Selective area epitaxy (SAE) provides the path for scalable fabrication of semiconductor nanostructures in a device-compatible configuration. In the current paradigm, SAE is understood as localized epitaxy, and is modelled by combining planar and self-assembled nanowire growth mechanisms. Here we use GaAs SAE as a model system to provide a different perspective. First, we provide evidence of the significant impact of the annealing stage in the calculation of the growth rates. Then, by elucidating the effect of geometrical constraints on the growth of the semiconductor crystal, we demonstrate the role of adatom desorption and resorption beyond the direct-impingement and diffusion-limited regime. Our theoretical model explains the effect of these constraints on the growth, and in particular why the SAE growth rate is highly sensitive to the pattern geometry. Finally, the disagreement of the model at the largest pitch points to non-negligible multiple adatom recycling between patterned features. Overall, our findings point out the importance of considering adatom diffusion, adsorption and desorption dynamics in designing the SAE pattern to create pre-determined nanoscale structures across a wafer. These results are fundamental for the SAE process to become viable in the semiconductor industry.

Nanoscale Mapping of Light Emission in Nanospade-Based InGaAs Quantum Wells Integrated on Si(100): Implications for Dual Light-Emitting Devices

III-V semiconductors outperform Si in many optoelectronics applications due to their high carrier mobility, efficient light emission and absorption processes, and the possibility to engineer their band gap through alloying. However, complementing Si technology with III-V semiconductors by integration on Si(100) remains a challenge still today. Vertical nanospades (NSPDs) are quasi-bi-crystal III-V nanostructures that grow on Si(100). Here, we showcase the potential of these structures in optoelectronics application by demonstrating InGaAs heterostructures on GaAs NSPDs that exhibit bright emission in the near-infrared region. Using cathodoluminescence hyperspectral imaging, we are able to study light emission properties at a few nanometers of spatial resolution, well below the optical diffraction limit. We observe a symmetric spatial luminescence splitting throughout the NSPD. We correlate this characteristic to the structure's crystal nature, thus opening new perspectives for dual wavelength light-emitting diode structures. This work paves the path for integrating optically active III-V structures on the Si(100) platform.

GaAs nanowires on Si nanopillars: towards large scale, phase-engineered arrays

Large-scale patterning for vapor-liquid-solid growth of III-V nanowires is a challenge given the required feature size for patterning (45 to 60 nm holes). In fact, arrays are traditionally manufactured using electron-beam lithography,for which processing times increase greatly when expanding the exposure area. In order to bring nanowire arrays one step closer to the wafer-scale we take a different approach and replace patterned nanoscale holes with Si nanopillar arrays. The method is compatible with photolithography methods such as phase-shift lithography or deep ultraviolet (DUV) stepper lithography. We provide clear evidence on the advantage of using nanopillars as opposed to nanoscale holes both for the control on the growth mechanisms and for the scalability. We identify the engineering of the contact angle as the key parameter to optimize the yield. In particular, we demonstrate how nanopillar oxidation is key to stabilize the Ga catalyst droplet and engineer the contact angle. We demonstrate how the position of the triple phase line at the SiO₂/Si as opposed to the SiO₂/vacuum interface is central for a successful growth. We compare our experiments with simulations performed in surface evolver™ and observe a strong correlation. Large-scale arrays using phase-shift lithography result in a maximum local vertical yield of 67% and a global chip-scale yield of 40%. We believe that, through a greater control over key processing steps typically achieved in a semiconductor fab it is possible to push this yield to 90+% and open perspectives for deterministic nanowire phase engineering at the wafer-scale.

Remote Doping of Scalable Nanowire Branches

Selective-area epitaxy provides a path toward high crystal quality, scalable, complex nanowire networks. These high-quality networks could be used in topological quantum computing as well as in ultrafast photodetection schemes. Control of the carrier density and mean free path in these devices is key for all of these applications. Factors that affect the mean free path include scattering by surfaces, donors, defects, and impurities. Here, we demonstrate how to reduce donor scattering in InGaAs nanowire networks by adopting a remote-doping strategy. Low-temperature magnetotransport measurements indicate weak anti-localization-a signature of strong spin-orbit interaction-across a nanowire Y-junction. This work serves as a blueprint for achieving remotely doped, ultraclean, and scalable nanowire networks for quantum technologies.

Orientation-Controlled Nonradiative Energy Transfer to Colloidal Nanoplatelets: Engineering Dipole Orientation Factor

We proposed and showed strongly orientation-controlled Förster resonance energy transfer (FRET) to highly anisotropic CdSe nanoplatelets (NPLs). For this purpose, we developed a liquid-air interface self-assembly technique specific to depositing a complete monolayer of NPLs only in a single desired orientation, either fully stacked (edge-up) or fully nonstacked (face-down), with near-unity surface coverage and across large areas over 20 cm². These NPL monolayers were employed as acceptors in an energy transfer working model system to pair with CdZnS/ZnS core/shell quantum dots (QDs) as donors. We found the resulting energy transfer from the QDs to be significantly accelerated (by up to 50%) to the edge-up NPL monolayer compared to the face-down one. We revealed that this acceleration of FRET is accounted for by the enhancement of the dipole-dipole interaction factor between a QD-NPL pair (increased from 1/3 to 5/6) as well as the closer packing of NPLs with stacking. Also systematically studying the distance-dependence of FRET between QDs and NPL monolayers via varying their separation (d) with a dielectric spacer, we found out that the FRET rate scales with d^-4 regardless of the specific NPL orientation. Our FRET model, which is based on the original Förster theory, computes the FRET efficiencies in excellent agreement with our experimental results and explains well the enhancement of FRET to NPLs with stacking. These findings indicate that the geometrical orientation of NPLs and thereby their dipole interaction strength can be exploited as an additional degree of freedom to control and tune the energy transfer rate.

CdTe Quantum Dot-Functionalized P25 Titania Composite with Enhanced Photocatalytic NO2 Storage Selectivity under UV and Vis Irradiation

Composite systems of P25 (titania) functionalized with thioglycolic acid (TGA)-capped CdTe colloidal quantum dots (QDs) were synthesized, structurally characterized, and photocatalytically tested in the photocatalytic NO _x oxidation and storage during NO(g) + O₂(g) reaction. Pure P25 yielded moderate-to-high NO conversion (31% in UV-A and 40% in visible (vis)) but exhibited extremely poor selectivity toward NO _x storage in solid state (25% in UV-A and 35% in vis). Therefore, P25 could efficiently photooxidize NO(g) + O₂(g) into NO₂; however, it failed to store photogenerated NO₂ and released toxic NO₂(g) to the atmosphere. CdTe QD-functionalized P25 revealed a major boost in photocatalytic performance with respect to pure P25, where NO conversion reached 42% under UV-A and 43% under vis illumination, while the respective selectivity climbed up to 92 and 97%, rendering the CdTe/P25 composite system an efficient broad-band photocatalyst, which can harvest both UV-A and vis light efficiently and display a strong NO _x abatement effect. Control experiments suggested that photocatalytic active sites responsible for the NO(g) + O₂(g) photooxidation and formation of NO₂ reside mostly on titania, while the main functions of the TGA capping agent and the CdTe QDs are associated with the photocatalytic conversion of the generated NO₂ to the adsorbed NO _x species, significantly boosting the selectivity toward solid-state NO _x storage. Reuse experiments showed that photocatalytic performance of the CdTe/P25 system can be preserved to a reasonable extent with only a moderate decrease in the photocatalytic performance. Although some decrease in the photocatalytic activity was observed after aging, CdTe/P25 could still outperform P25 benchmark photocatalyst. Increasing CdTe QDs loading from the currently optimized minuscule concentrations could be a useful strategy to increase further the catalytic lifetime/stability of the CdTe/P25 system with only a minor penalty in catalytic activity.

Ultrahigh-efficiency aqueous flat nanocrystals of CdSe/CdS@Cd1-xZnxS colloidal core/crown@alloyed-shell quantum wells

Colloidal semiconductor nanoplatelets (NPLs) are highly promising luminescent materials owing to their exceptionally narrow emission spectra. While high-efficiency NPLs in non-polar organic media can be obtained readily, NPLs in aqueous media suffer from extremely low quantum yields (QYs), which completely undermines their potential, especially in biological applications. Here, we show high-efficiency water-soluble CdSe/CdS@Cd1-xZnxS core/crown@shell NPLs formed by layer-by-layer grown and composition-tuned gradient Cd1-xZnxS shells on CdSe/CdS core/crown seeds. Such control of shell composition with monolayer precision and effective peripheral crown passivation, together with the compact capping density of short 3-mercaptopropionic acid ligands, allow for QYs reaching 90% in water, accompanied by a significantly increased photoluminescence lifetime (∼35 ns), indicating the suppression of nonradiative channels in these NPLs. We also demonstrate the controlled attachment of these NPLs without stacking at the nanoscale by taking advantage of their 2D geometry and hydrophilicity. This is a significant step in achieving controlled assemblies and overcoming the stacking process, which otherwise undermines their film formation and performance in optoelectronic applications. Moreover, we show that the parallel orientation of such NPLs achieved by the controlled attachment enables directed emission perpendicular to the surface of the NPL films, which is highly advantageous for light extraction in light-emitting platforms.

Near-Unity Efficiency Energy Transfer from Colloidal Semiconductor Quantum Wells of CdSe/CdS Nanoplatelets to a Monolayer of MoS2

A hybrid structure of the quasi-2D colloidal semiconductor quantum wells assembled with a single layer of 2D transition metal dichalcogenides offers the possibility of highly strong dipole-to-dipole coupling, which may enable extraordinary levels of efficiency in Förster resonance energy transfer (FRET). Here, we show ultrahigh-efficiency FRET from the ensemble thin films of CdSe/CdS nanoplatelets (NPLs) to a MoS₂ monolayer. From time-resolved fluorescence spectroscopy, we observed the suppression of the photoluminescence of the NPLs corresponding to the total rate of energy transfer from ∼0.4 to 268 ns^-1. Using an Al₂O₃ separating layer between CdSe/CdS and MoS₂ with thickness tuned from 5 to 1 nm, we found that FRET takes place 7- to 88-fold faster than the Auger recombination in CdSe-based NPLs. Our measurements reveal that the FRET rate scales down with d^-2 for the donor of CdSe/CdS NPLs and the acceptor of the MoS₂ monolayer, d being the center-to-center distance between this FRET pair. A full electromagnetic model explains the behavior of this d^-2 system. This scaling arises from the delocalization of the dipole fields in the ensemble thin film of the NPLs and full distribution of the electric field across the layer of MoS₂. This d^-2 dependency results in an extraordinarily long Förster radius of ∼33 nm.

The Frequency and Determinants of Metabolic Syndrome in Patients with Operable Stage I-III Breast Cancer

Background: Metabolic syndrome is a cluster of multiple risk factors including obesity, insulin resistance, hypertriglyceridemia, low HDL (high density lipoprotein), and hypertension. Metabolic syndrome is associated with an increased risk of breast cancer. We evaluated the frequency and determinants of metabolic syndrome in patients with operable stage I-III breast cancer.Methods: In this cross-sectional study we analyzed the frequency and determinants of metabolic syndrome in patients with stage I-III breast cancer. Metabolic syndrome was defined according to NCEP (National Cholesterol Education Program) definitions. Data on metabolic syndrome criteria were collected along with demographic data, tumor size, grade, lymph node, estrogen, progesterone, HER2 status, grade and history of chemotherapy/endocrine therapy.Results: A total of 331 patients were analyzed. Median age was 50.0 years (range 20-84 years). Eighty-five patients were using tamoxifen, 98 patients were using aromatase inhibitors and the remaining 148 patients were not receiving hormonal therapy (newly diagnosed and/or triple-negative patients). According to the NCEP criteria 48.0% of the patients had metabolic syndrome. More patients receiving aromatase inhibitors had metabolic syndrome than those receiving tamoxifen (60.2% vs. 37.6%, p = 0.008). The frequency of MS among those not taking any hormonal therapy was 45.9%. Additionally, post-menopausal patients had higher rate of MS compared to pre-menopausal ones (53.4% vs. 25.0% p=<0.001). Patients with HER2 positive tumors and patients who had a history of oral contraceptive use had lower rates of metabolic syndrome than those with HER2 negative tumors and no oral contraceptive use, respectively (40,0% vs. 53,7% for HER2, p=0.028 and 32,6% vs. 50,3% for oral contraceptive use, p=0.034).There was no significant correlation between the presence of metabolic syndrome and estrogen/progesterone receptor status, tumor size, nodal status, stage, grade, adjuvant chemotherapy, hormone replacement therapy, smoking history.Conclusions: Nearly half of the patients with stage I-III breast cancer had metabolic syndrome. Adjuvant aromatase inhibitor therapy was found to be associated with higher rate of metabolic syndrome whereas history of oral contraceptive use and HER2 positivity were associated with lower rate. Whether the aromatase inhibitors contribute the development of metabolic syndrome or not needs to be elucidated by future prospective studies.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 5121.

Ultrasonography and fluoroscopy-guided insertion of chest ports

AIMS

To evaluate the results of ultrasonography and fluoroscopy-guided percutaneous placement of internal jugular vein catheters and subcutaneous chest port system in patients with carcinoma.

METHODS

The data of 1418 patients in whom the devices were implanted from 2003 to 2007 in interventional radiology unit were evaluated prospectively.

RESULTS

The median age was 45 years (range 23-70), 658 were women and 760 were men. Technical success in implanting the devices was 100%. No instances of major complications such as pneumothorax, hemothorax, catheter tip malposition, air embolism were seen. The overall complication rate was 5%. Overall follow-up of patients was 699 074 catheter days with the mean function time of 493 (range 130-1215) days.

CONCLUSIONS

With the benefit of ultrasonography and fluoroscopy guidance, chest port systems can be implanted by interventional radiologists without major insertion complications and with a higher success rate than those reported in surgical placements.

Falls and the elderly: is there any difference in the developing world? A cross-sectional study from Turkey

The phenomenon of falls is not well studied in developing world. However, being aware of possible correlates for falls specific to different populations and trying to eliminate these factors is very important to prevent falls. This study investigated occurrence and correlates of falls among elderly in a developing country, Turkey. A total of 2322 patients aged 65 years and over presented to outpatient clinics of a reference hospital were included in this cross-sectional study. All patients had a complete comprehensive geriatric assessment and questioned for fall history. Correlates for falls were analyzed by using logistic regression. The mean age of participants was 71.8 years; 63.5% were female and 28.5% were found to have fallen within one year. Female sex, visual problems, auditory problems, use of mobility aids, mobility problems and depression were the only independent correlates for falls. Although the cross-sectional design of this study may not prove the causal role of the risk indicators, the size of the study group as well as the large number of possible correlates examined enriches the study. The results from this cross-sectional study form a basis for further prospective study on falls in the Turkish elderly population.

MMPI-2 profiles of patients with intractable epilepsy

MMPI-2 profiles of 93 presurgical intractable epilepsy patients were examined using Ward's method of cluster analysis. Three clusters were identified. The means of each cluster suggest that 45% of the sample had minimal psychological complaints, 30% presented with generalized clinical elevations, and 25% of the patients had profiles of intermediate elevations with a tendency to emphasize somatic complaints and/or depression. Gender, age of seizure onset, and seizure laterality were not found to be uniquely associated with the cluster profiles. Further examination of correlates of group membership is warranted to provide information for treatment planning.

Molar tooth sign in Joubert syndrome: clinical, radiologic, and pathologic significance

Joubert syndrome is a rare autosomal-recessive condition characterized by early hyperpnea and apnea, developmental delay, and truncal ataxia. We previously described key ocular motor signs in Joubert syndrome and the molar tooth sign resulting from dysplasia of the isthmic segment of the brain stem, superior cerebellar peduncles, and vermis. In this study, we obtained clinical and developmental data in 61 cases, and radiologic data in 46 of these, to determine the prevalence of the molar tooth sign in a large sample, and to ensure that magnetic resonance images obtained for study were representative of the Joubert syndrome population at large. We studied the morphology of the isthmic segment of the pontomesencephalic junction, the segment of the brain stem derived from the primitive isthmus. Portions of the cerebellum analyzed included the superior cerebellar peduncles, the anterior and posterior lobes of the vermis, and the flocculonodular lobe. In one case, autopsy of the brain was performed. The average age at diagnosis was 33 months. All patients were hypotonic and developmentally delayed. The molar tooth sign was present in 85% of cases with 13% of these showing additional malformations. All patients without the molar tooth sign had other mimicking conditions such as neocerebellar dysgenesis, isolated vermian atrophy, cerebellar aplasia, and cystic dilation of the cisterna magna. Autopsy showed aplasia of the cerebellar vermis with dysplasia of the dentate nucleus, elongated locus coeruleus, and marked dysplasia of the caudal medulla. A better understanding of the clinical, radiologic, and pathologic features of Joubert syndrome should help uncover the genetic basis for the syndrome.

Neurobehavioral development in Joubert syndrome

Research on children with Joubert syndrome has focused on brain structural abnormalities and associated clinical symptoms. The degree of developmental delay has not been objectively reported. We investigated the neurobehavioral development of children with Joubert syndrome through neurobehavioral assessment in the largest sample to date. Thirty-two parents of children with Joubert syndrome completed the Child Development Inventory and magnetic resonance imaging (MRI) data was gathered on 17 of these children. Results indicate that 94% were severely impaired according to the Child Development Inventory, with age being positively correlated with degree of neurobehavioral impairment. The average developmental age of our sample was 19 months (63% below chronological age). Severity of illness as measured by the General Development scale of the Child Development Inventory and severity of illness as measured by MRI (overall severity rating) did not yield consistent data regarding severity of the midbrain and cerebellar malformations. Similarly, markers of abnormal cerebral development such as cortical atrophy and delayed myelination were independent of severity of illness ratings on the Child Development Inventory. The degree of developmental delay in Joubert syndrome and the severity of gross central nervous system malformations appear independent.

Neuropsychological deficits are correlated with frontal hypometabolism in positron emission tomography studies of older alcoholic patients

In an extension of previous work, we studied the behavioral correlates of medial frontal lobe glucose hypometabolism in chronically alcohol-dependent patients. Thirty-one male patients who were detoxified, medically stable, and free of other central nervous system risk factors for neuropsychological impairment were examined with (1) anatomic imaging (CT or MR), (2) functional imaging with [18F] fluorodeoxyglucose (18F-FDG) and positron emission tomography (PET), and (3) a battery of neuropsychological tests, including two measures of abstraction known to be generally sensitive to frontal lobe disease or dysfunction [the Wisconsin Card Sorting Test (WCST) and the Halstead Category Test (HCT)]. 18F-FDG PET data from 18 age- and sex-matched normal control subjects were used for comparison. All patients met criteria for severe alcohol dependence and for at least a mild degree of alcoholic-induced cognitive impairment. Although the mean IQ level of the alcoholic patients was in the average range, the concepts attained and the error scores on the WCST and HCT were significantly impaired in comparison with established norms. Local cerebral metabolic rate for glucose (LCMRglc) was significantly decreased in a sagittal strip of the medial frontal cortex in the alcoholic patients as compared with the normal controls. Comparison of data from PET scans and anatomic images indicated that the reduced LCMRglc could not be attributed to reduced amounts of tissue alone. A statistically significant relationship was found between LCMRglc in the medial frontal region of the cerebral cortex and performance on the WCST, but not the HCT. These findings suggest that chronic alcohol intake results in impaired function of cerebral tissue in the medial frontal region.(ABSTRACT TRUNCATED AT 250 WORDS)