Holographic three-dimensional telepresence using large-area photorefractive polymer.

Holography is a technique that is used to display objects or scenes in three dimensions. Such three-dimensional (3D) images, or holograms, can be seen with the unassisted eye and are very similar to how humans see the actual environment surrounding them. The concept of 3D telepresence, a real-time dynamic hologram depicting a scene occurring in a different location, has attracted considerable public interest since it was depicted in the original Star Wars film in 1977. However, the lack of sufficient computational power to produce realistic computer-generated holograms and the absence of large-area and dynamically updatable holographic recording media have prevented realization of the concept. Here we use a holographic stereographic technique and a photorefractive polymer material as the recording medium to demonstrate a holographic display that can refresh images every two seconds. A 50 Hz nanosecond pulsed laser is used to write the holographic pixels. Multicoloured holographic 3D images are produced by using angular multiplexing, and the full parallax display employs spatial multiplexing. 3D telepresence is demonstrated by taking multiple images from one location and transmitting the information via Ethernet to another location where the hologram is printed with the quasi-real-time dynamic 3D display. Further improvements could bring applications in telemedicine, prototyping, advertising, updatable 3D maps and entertainment.

Achieving enhanced gain in photorefractive polymers by eliminating electron contributions using large bias fields.

Photorefractive polymers have been extensively studied for over two decades and have found applications in holographic displays and optical image processing. The complexity of these materials arises from multiple charge contributions, for example, leading to the formation of competing photorefractive gratings. It has been recently shown that in a photorefractive polymer at relatively moderate applied electric fields the primary charge carriers (holes) establish an initial grating, followed by a subsequent competing grating (electrons) resulting in a decreased two-beam coupling and diffraction efficiencies. In this paper, it is shown that with relatively large sustainable bias fields, the two-beam coupling efficiency is enhanced owing to a decreased electron contribution. These results also explain the cause of dielectric breakdown experienced under large bias fields. Our conclusions are supported by self-pumped transient two-beam coupling and photocurrent measurements as a function of applied bias fields at different wavelengths.

Interdigitated coplanar electrodes for enhanced sensitivity in a photorefractive polymer.

Organic photorefractive polymer composites can be made to exhibit near 100% diffraction efficiency and fast writing times, though large external slants are needed to project the applied field onto the grating vector. We show here that the use of interdigitated electrodes on a single plane provides similar performance to these standard devices and geometries but without a external slant angle. This new device's structure also greatly improves the diffraction efficiency and sensitivity compared to less slanted standard devices necessary for some real applications, such as holographic displays, optical coherence imaging, and in-plane switching.

Grating dynamics in a photorefractive polymer with Alq(3) electron traps.

The electron transporting molecule tris(8-hydroxyquinoline) aluminum (Alq(3)) was added in low concentrations to a photorefractive polymer composite to provide trapping sites for electrons. This sample exhibited larger two-beam coupling gain, higher diffraction efficiency at lower voltages, and an increased dielectric breakdown strength compared to a control sample. The dynamics also revealed the presence of a competing grating, and a bipolar charge transport model is shown to fit the data. Overall, Alq(3) improves the response time, efficiency, and breakdown voltage without a significant increase in absorption or loss of phase stability. This has applications for reflection displays and pulsed writing, where charge trapping and generation are major factors limiting the usefulness of photorefractive polymers.

Automated PCR setup for forensic casework samples using the Normalization Wizard and PCR Setup robotic methods.

Human genome, pharmaceutical and research laboratories have long enjoyed the application of robotics to performing repetitive laboratory tasks. However, the utilization of robotics in forensic laboratories for processing casework samples is relatively new and poses particular challenges. Since the quantity and quality (a mixture versus a single source sample, the level of degradation, the presence of PCR inhibitors) of the DNA contained within a casework sample is unknown, particular attention must be paid to procedural susceptibility to contamination, as well as DNA yield, especially as it pertains to samples with little biological material. The Virginia Department of Forensic Science (VDFS) has successfully automated forensic casework DNA extraction utilizing the DNA IQ(trade mark) System in conjunction with the Biomek 2000 Automation Workstation. Human DNA quantitation is also performed in a near complete automated fashion utilizing the AluQuant Human DNA Quantitation System and the Biomek 2000 Automation Workstation. Recently, the PCR setup for casework samples has been automated, employing the Biomek 2000 Automation Workstation and Normalization Wizard, Genetic Identity version, which utilizes the quantitation data, imported into the software, to create a customized automated method for DNA dilution, unique to that plate of DNA samples. The PCR Setup software method, used in conjunction with the Normalization Wizard method and written for the Biomek 2000, functions to mix the diluted DNA samples, transfer the PCR master mix, and transfer the diluted DNA samples to PCR amplification tubes. Once the process is complete, the DNA extracts, still on the deck of the robot in PCR amplification strip tubes, are transferred to pre-labeled 1.5 mL tubes for long-term storage using an automated method. The automation of these steps in the process of forensic DNA casework analysis has been accomplished by performing extensive optimization, validation and testing of the software methods.

Villous adenomas of the rectum: the accuracy of clinical assessment.

To avoid an unnecessary radical operation, it is important for surgeons to identify a clinically benign villous tumor of the rectum, especially in the middle third area, where a transanal approach may not be feasible. If the high accuracy of this clinical impression can be achieved, alternative methods such as piecemeal snare excision, or electrocoagulation, or both are justified. To evaluate the diagnostic accuracy of a benign rectal villous tumor, 151 patients with totally excised rectal tumors were reviewed. All of these patients had soft and nonulcerated lesions and were judged to be benign. Induration and ulceration of the lesions signified malignancy and were excluded. One hundred and fourteen patients (76%) had benign villous adenomas, 23 patients (15%) had superficial carcinomas, and 14 patients (9%) had invasive carcinomas. Hence the accuracy of detecting a clinically benign villous tumor of the rectum was 91%. This is high enough to avoid a more radical procedure when the clinical impression is that of a benign villous tumor of the rectum.

Minor physical anomalies in schizophrenia patients, bipolar patients, and their siblings.

Minor physical anomalies (MPAs) are believed to reflect abnormalities in fetal neurodevelopment. Several studies have shown that schizophrenia patients have more MPAs than normal controls, but little is known about the meaning of this increased rate of MPAs. The current study first attempted to determine whether the increased MPAs are associated with schizophrenia in particular or with psychosis in general. Second, the study tested whether the patients' siblings also show an increased rate of MPAs by assessing MPAs in schizophrenia patients, bipolar manic patients, the siblings from each group of patients, and normal controls. The schizophrenia patients had significantly more MPAs than normal controls and bipolar patients. The rate of MPAs in bipolar patients did not differ from normal controls. This pattern suggests that MPAs have some degree of specificity to schizophrenia. Both sibling groups had fewer MPAs than the patients, and this difference was significant for the comparison between schizophrenia patients and their siblings. When viewed within a vulnerability-stress model, the results are consistent with the theory that MPAs may reflect early, largely extra-genetic, stressful events.

Restorative proctocolectomy with ileal reservoir and ileoanal anastomosis.

An initial experience with a technique of restorative proctocolectomy utilizing a rectal mucosectomy, total colectomy, and ileal reservoir (Parks S-pouch) with ileoanal anastomosis for patients with ulcerative colitis and familial polyposis is presented. Although there were no deaths, significant morbidity did occur and was attributed to the use of a temporary loop ileostomy which may not be necessary. Early functional results are promising and to date, patient satisfaction is very high.

Preliminary evidence for an association between minor physical anomalies and second trimester neurodevelopment in schizophrenia.

Two types of markers, dermatoglyphics and minor physical anomalies, have been used as indicators of problems with fetal neurodevelopment in schizophrenia. The degree to which these markers overlap is not known. While it is agreed that abnormal dermatoglyphics reflect early second trimester maldevelopment, the timing of the development of minor physical anomalies has not been determined. Forty-six schizophrenic patients received assessments for minor physical anomalies, dermatoglyphics (right-left ridge count asymmetry and total finger ridge count), and information processing. Higher scores for minor physical anomalies were associated with greater dermatoglyphic asymmetry. Patients who had both types of indicators (high minor physical anomalies and dermatoglyphic asymmetry) did not differ on information-processing measures from patients who had neither. On the basis of the timing of dermatoglyphic development (weeks 14-22 of gestation), the association between minor physical anomalies and dermatoglyphic asymmetry suggests that the relatively high rate of minor physical anomalies observed in schizophrenia can be considered to reflect at least second trimester maldevelopment.

Colic medication and apparent life-threatening events.

Eight infants with histories of apnea and cyanosis were referred to the Southwest SIDS Research Institute for evaluation of apparent life threatening events (ALTE). All of the infants had been treated for colic with a 1:1 concentration of dimenhydrinate (Dramamine) and phenobarbital, hyoscyamine sulfate, atropine sulfate and scopolamine hydrobromide (Donnatal). The medication was pre-mixed by local pharmacists. A comprehensive work-up failed to reveal a cause for the ALTE in any infant. The Dramamine/Donnatal mixture was withdrawn and polygraphic evaluation was conducted. Cardiorespiratory abnormalities were identified in all eight infants and significant gastroesophageal reflux (GER) was documented in four. The possibility that colic medication contributes to cardiorespiratory instability and GER in vulnerable infants requires serious consideration and further evaluation.

Podiatric utilization referral patterns at an Army medical center.

Presented is the first descriptive data on a large military Podiatry Clinic supporting largely combat troops. Data consist of initial podiatric problems of soldiers and other beneficiaries of podiatric care. Demographic, physician referral patterns, and other pertinent summarized survey information of outpatient utilization at the Podiatry Clinic, Madigan Army Medical Center, Fort Lewis, Washington, are examined. Findings are based on new and initial consult referrals from the month of November 1988. The results indicated that some clinics needed inservices and further education concerning podiatric care. This study has led to the implementation of changes which have resulted in better and more timely patient care.

The interpretation of office radiographs by family physicians.

This study prospectively compared the interpretations of family practice residents and faculty with those of radiologists on 532 office radiographs using a uniform protocol. A total of 136 family practice residents (44 first-year, 40 second-year, 52 third-year) and 42 full-time and part-time faculty participated in the study along with 30 radiologists. The mix of radiographs evaluated was as follows: 44 percent chest, 20 percent lower extremity, 6 percent head, 4 percent lumbosacral spine, 3 percent cervical-thoracic spine, and 3 percent abdomen-pelvis. Interpretation concordance rates between family physicians and radiologists, by level of training, were as follows: first-year residents 83.0 percent, second-year residents 84.4 percent, third-year residents 86.0 percent, and faculty 88.6 percent. Concordance after the resident and faculty preceptor discussed the film and provided a collaborative interpretation was 92.1 percent. This finding compares with previously reported error rates of 10 to 40 percent between experienced radiologists. Only 10.3 percent of the discordant readings (0.8 percent of all radiographs) contained significant discordancies that may have affected patient management or outcome. Had the family physicians been given the option to refer an x-ray film to the radiologist, all x-ray films containing significant discordancies would have been referred.

Frostbite.

Frostbite can cause loss of life and limbs. Proper treatment and follow-up care are essential in reducing morbidity and mortality. Management of the frostbite patient consists of three stages. Initial care includes protection of the extremity from trauma or partial thawing. The second stage consists of rapid rewarming in a whirlpool bath containing hot water, with continued protection of the tissues. The third stage is long-term care of the affected body parts.

Intra-operative contamination of bone and cartilage during an Austin bunionectomy.

During an Austin bunionectomy the potential exists for the head of the metatarsal to leave the sterile field and become contaminated. The authors present a case in which this occurred, with a 20-month follow-up. Possible options for decontamination are reviewed.

Comparison of oblique closing base wedge osteotomies of the first metatarsal: stripping versus nonstripping of the periosteum.

The authors present a study comparing two methods of performing the oblique closing base wedge osteotomy of the first metatarsal for correction of hallux abducto valgus deformity. In one group, the periosteum was stripped from the metatarsal prior to performing the osteotomy, and in the other group, the osteotomy was performed through the periosteum. Sixty-five osteotomies are included in the study. This article discusses the closing base wedge osteotomy, fracture healing and the role of the periosteum, the blood supply to the first metatarsal, and the effects of periosteal stripping. Also included is a presentation of the surgical technique used, a statistical review of the procedures performed, a critical discussion summarizing the results, and a discussion of the postoperative complications encountered.

Is subtotal colectomy a viable option in the management of chronic constipation?

To determine if subtotal colectomy constitutes a valuable alternative in the treatment of patients with chronic constipation, a retrospective review of 52 consecutive patients who underwent subtotal colectomy between January 1980 and August 1985 was undertaken. Forty-six patients underwent ileodistal sigmoidostomy while five patients underwent ileoproctostomy and five with concomitant rectal prolapse underwent simultaneous proctopexy. A mortality rate of 3.8 percent and morbidity rate of 60 percent were encountered. The most frequently occurring complication was small-bowel obstruction, which occurred in 36 percent, and necessitated laparotomy in 66 percent. Additional procedures were necessary in five patients because of newly discovered rectal prolapse (two patients), rectocele (one patient), unrelieved constipation (one patient), and incapacitating incontinence (one patient). Follow-up data available in 94 percent (mean, 46 months) disclosed that patients had an average of 2.8 bowel movements per day without the use of laxatives (89 percent) or enemas (80 percent). Overall, 79 percent were satisfied with the final outcome. It is concluded that subtotal colectomy constitutes a viable option in the treatment of chronic constipation. However, the significant morbidity and mortality associated with the procedure dictate the need for careful patient selection on the basis of appropriate physiologic testing.

Abrupt onset of severe pain at term. A case report.

This case report involves an adolescent primigravida at term who was admitted with urinary complaints to the labor and delivery unit of a medical center. Within an hour, she suddenly began screaming and complaining of severe pain running from her anterior pelvis through her vagina and up her spine. Three days of very challenging co-management of the patient, with several recurrences of acute pain, followed. Differential diagnoses that could explain this patient's symptoms are reviewed and discussed. Difficult management issues, including the stress of clinical management in the face of unidentified disease processes, are addressed. Lacking a certain diagnosis even retrospectively, the authors request comments from readers.