Beyond power amplification: latch-mediated spring actuation is an emerging framework for the study of diverse elastic systems.

Rapid biological movements, such as the extraordinary strikes of mantis shrimp and accelerations of jumping insects, have captivated generations of scientists and engineers. These organisms store energy in elastic structures (e.g. springs) and then rapidly release it using latches, such that movement is driven by the rapid conversion of stored elastic to kinetic energy using springs, with the dynamics of this conversion mediated by latches. Initially drawn to these systems by an interest in the muscle power limits of small jumping insects, biologists established the idea of power amplification, which refers both to a measurement technique and to a conceptual framework defined by the mechanical power output of a system exceeding muscle limits. However, the field of fast elastically driven movements has expanded to encompass diverse biological and synthetic systems that do not have muscles - such as the surface tension catapults of fungal spores and launches of plant seeds. Furthermore, while latches have been recognized as an essential part of many elastic systems, their role in mediating the storage and release of elastic energy from the spring is only now being elucidated. Here, we critically examine the metrics and concepts of power amplification and encourage a framework centered on latch-mediated spring actuation (LaMSA). We emphasize approaches and metrics of LaMSA systems that will forge a pathway toward a principled, interdisciplinary field.

Spring and latch dynamics can act as control pathways in ultrafast systems.

Ultrafast movements propelled by springs and released by latches are thought limited to energetic adjustments prior to movement, and seemingly cannot adjust once movement begins. Even so, across the tree of life, ultrafast organisms navigate dynamic environments and generate a range of movements, suggesting unrecognized capabilities for control. We develop a framework of control pathways leveraging the non-linear dynamics of spring-propelled, latch-released systems. We analytically model spring dynamics and develop reduced-parameter models of latch dynamics to quantify how they can be tuned internally or through changing external environments. Using Lagrangian mechanics, we test feedforward and feedback control implementation via spring and latch dynamics. We establish through empirically-informed modeling that ultrafast movement can be controllably varied during latch release and spring propulsion. A deeper understanding of the interconnection between multiple control pathways, and the tunability of each control pathway, in ultrafast biomechanical systems presented here has the potential to expand the capabilities of synthetic ultra-fast systems and provides a new framework to understand the behaviors of fast organisms subject to perturbations and environmental non-idealities.

Close relationship of the major excreted protein of transformed murine fibroblasts to thiol-dependent cathepsins.

Complementary DNA clones corresponding to 638 nucleotides of the messenger RNA encoding the major portion of murine major excreted protein have been isolated and sequenced. The amino acid sequence of a part of the murine major excreted protein deduced from the DNA sequence reveals substantial and significant homology with the cysteine proteases actinidin, rat cathepsin H, and papain. Since the amount of murine major excreted protein secreted by cultured cells is often enhanced by transformation, it is implicated in oncogenic phenomena and may play a role in the metastatic process by virtue of its proteolytic activity.

A refined vector system for the in vitro construction of single-copy transcriptional or translational fusions to lacZ.

New single-copy vectors based on lambda phage have been developed for creating either transcriptional (operon) or translational (gene) fusions to the lacZ gene. The improvements of these vectors over the previous lambda TL61 vector include: (i) incorporation of a tetracycline-resistance-encoding gene (TcR) to permit direct selection of lysogens, (ii) low-background beta-galactosidase activity, (iii) the ability to accept DNA inserts up to 8 kb in size, and (iv) an expanded multiple cloning site (MCS). The new transcriptional fusion vector retains the RNase III processing site downstream from the MCS which ensures independent translation of lacZ. The set of three translational fusion vectors allow for convenient subcloning in any of the three translational reading frames.

A set of compatible tac promoter expression vectors.

A series of expression vectors have been developed which all contain an identical expression cassette comprised of the lacIq gene, the tac promoter, a multiple cloning site (MCS) and a downstream transcriptional terminator. This cassette has been inserted into four distinct plasmid backbones, each of which is from a separate incompatibility group and carries a different drug resistance gene. Therefore, different combinations of these expression plasmids can be stably maintained together.

Induction of T-cells differentiation in vitro by thymus epithelial cells.

Thymus-reticular epithelial cells (TE-cells) were grown in a cell culture devoid of any lymphocytic elements. These cells were able to induce T-cell differentiation in spleen cells from T-dificient mice as expressed by con-A responsiveness and GvH reactivity. It was also shown that xenogeneic rat TE cells were as effective in the induction of T-cell differentiation in vitro as syngeneic TE cells. This system is therefore ideal for the study of T-cell development.

Measuring individual plate waste in school lunches. Visual estimation and children's ratings vs. actual weighing of plate waste.

Weighing individual plate waste is time consuming and often impractical. As alternatives, two indirect measures were evaluated-visual estimation and children's ratings of plate waste. Visual estimations were highly correlated with percent waste (r = 0.93) and were quite accurate. Ratings by children were less accurate but were still considered a useful indirect measure that should be further developed.

The Ohio AIDS Prevention Survey: a study of psychometric properties.

The reliability of a measuring instrument is a major criterion for assessing its quality and adequacy. This article describes reliability pilot testing done with the Ohio AIDS Prevention Survey (Fellner & Thomas, 1989-90) in a sample of sexually active women of childbearing age. Previous alpha reliabilities of the knowledge scale of the survey have ranged from .71-.81, while the reliabilities of the attitudes and beliefs scale have ranged from .33-.45. In this sample, reliability measures for the knowledge and attitudes and beliefs scales were .65 and .45, respectively. The results of this study indicate that the Ohio AIDS Prevention Survey is clearly in its developmental stages and that further development of the survey is necessary prior to continued use in public health settings.

The effect of a single affective HIV/AIDS educational program on college students' knowledge and attitudes.

The number of AIDS cases, since its identification by the Centers for Disease Control (CDC) in 1981, has continued to escalate at a very alarming rate. A population at increased risk of acquiring AIDS is college students, because of their behavior, especially personal and sexual exploration (D'Augelli & Kennedy, 1989; American College Health Association, 1988; Hirschorn, 1987).

The Cybex II evaluation of lateral ankle ligamentous reconstructions.

Chronic lateral ankle instability is a costly disability to the athlete. The Chrisman-Snook and Evans lateral ligamentous reconstructions are two procedures frequently performed to correct ligamentous instability. The entire peroneus brevis tendon is transected in the Evans procedure, thus sacrificing its eversion strength and power. The importance of preserving the eversion function of the peroneus brevis muscle is speculative, but may be of significance for good long-term results. The ankle eversion strength and power of 10 patients with Chrisman-Snook and 10 patients with Evans lateral ligamentous reconstructions were objectively evaluated with the Cybex II Isokinetic Dynamometer. The mean postoperative time to testing was 4.2 years. The uninvolved ankle was also tested and used as the normal strength of the patient. Twenty normal controls matched for age, sex, and physical activity were tested to assure maximum test reproducibility. The eversion strength was tested at several speeds, but torque values at speeds of 30 and 120 deg/sec were selected for analysis. At slow speeds, 30 deg/sec, and ankles that had Evans and Chrisman-Snook reconstruction were 4% and 7% weaker, respectively, than the contralateral normal ankles. At 120 deg/second the ankles were 8% and 9% weaker with the Evans and Chrisman-Snook reconstructions, respectively. A three factor analysis of variance with repeated measures on two of the factors was used to analyze the data.(ABSTRACT TRUNCATED AT 250 WORDS)

Computerized tomography in the evaluation of peroneal tendon dislocation. A report of two cases.

Dislocation or subluxation of a peroneal tendon is a relatively uncommon entity, and the diagnosis is rarely made at the time of initial injury. If untreated, chronic lateral instability and pain may develop which can be a diagnostic dilemma. These patients usually will have a history of frequent episodes of ankle instability and may be aware of a pop or snap just prior to the episode of instability. There is usually no significant anterior drawer or inversion laxity present on stress testing. Unfortunately, it is often difficult to passively or actively dislocate the involved peroneal tendon. Surgical treatment may have to be recommended on strong suspicion alone. Two patients with chronic lateral ankle pain underwent computerized tomography preoperatively and postoperatively. In addition, eight normal ankles were scanned for comparison. In the two cases of peroneal tendon dislocations presented, computerized tomography was found to be a very beneficial aid in making the diagnosis, and may be of significant value in those with suspected peroneal tendon subluxation/dislocations.

Osteoporosis: implications for risk reduction in the college setting.

Osteoporosis is often considered a chronic disease of older adulthood. As with many chronic diseases, lifestyle behaviors adopted during young adulthood are important risk factors for future development of osteoporosis. The college student population represents the age group in which optimal bone development is likely to occur and certain lifestyle behaviors are reinforced. Therefore, risk factors for osteoporosis, including nutritional insufficiency of calcium and vitamin D, smoking, alcohol abuse, excessive exercise, use of steroids, and high-protein diets, have special relevance for this target population. The authors examine risk factors for osteoporosis that are especially relevant to the college health setting and offer intervention strategies for college health professionals.

Biomechanical foot orthotics: a retrospective study.

Foot orthotics are becoming recognized as an important consideration in the correction of lower extremity alignment and mechanical dysfunctions. There are many different foot orthotics on the market today claiming to relieve pain and enhance foot function. Unfortunately, minimal research has been conducted investigating the effectiveness of foot orthotics in adult patient populations. The purpose of this study was to determine the degree of pain relief experienced by patients, the ability of patients to return to their previous levels of activity associated with the duration of use of the orthotics, and patient compliance. This study also discusses the specific deformity for which the orthotic was prescribed and the degree of posting necessary to compensate for the deformity. Fifty-three subjects, 20 males and 33 females, responded to a questionnaire survey. The type of foot deformity and the orthotic prescription are also presented for each subject. The responses to the questions were correlated with an individual patient chart review. In addition, chi-square analysis was used to determine the level of significance between the specific deformity and the age and weight of the patients. The level of significance was determined between the patient's ability to adjust to the orthotics and their continued use of the orthotics. Finally, the significance of the orthotic treatment was compared to four other treatment interventions. Ninety-six percent of the patients reported relief from pain with the use of the prescribed foot orthotic. Ninety-four percent of the patients were still wearing the orthotic, and 52% reported that they would not leave home without them in their shoes at the time the survey was conducted. Seventy percent of the patients reported that they were able to return to their previous level of activity with the use of the foot orthotics.J Orthop Sports Phys Ther 1988;10(6):205-212.

Arthroscopy of the elbow.

For arthroscopy of the elbow to be safe and effective, the arthroscopist must develop a systematic and reproducible arthroscopic examination technique. We believe that the technique and the identification of anatomic structures described in this article provide a safe and reliable means of performing this procedure. Attention to detail, especially when establishing the portals, is essential in performing a safe examination and in avoiding damage to the neurovascular structures. We prefer the 4-mm, 30-degree-angled arthroscope. It provides the wide field of view necessary for both diagnostic and operative elbow arthroscopy. The large percentage of excellent and good results in patients who have had correction of mechanical disorders of the elbow has been encouraging. Removal of loose bodies and resection of impinging olecranon osteophytes produced the best functional results. Chondroplasties of the radial head and capitellum produced less satisfactory results than did the correction of mechanical disorders. In conclusion, arthroscopy of the elbow is an effective diagnostic procedure and is effective in treating certain intraarticular problems with minimal morbidity and rapid return to function. However, attention to detail is essential to prevent compromise of the surrounding neurovascular structures or damage to the delicate articular cartilage.

Life span development: intervention implications for concepts of aging.

The life span theory of development is based on the notion that development occurs at all ages. A person's developmental history influences his or her behavior later in life. Following this assumption, the ability of an elderly person to cope with health problems is related to past experience in coping with similar problems or life events. The goal of intervention related to life span development serves two purposes: to help individuals overlap positive health behaviors that will be sustained throughout life and to discuss the role and impact of life events on their ability to cope with later problems. The school health program provides an excellent vehicle for achieving these goals.

Report of the 1984 ASHA membership survey.

The results of the most recent American School Health Association (ASHA) membership survey, conducted by ASHA to retain its continuing education units provider status granted in 1981 by the American Nurses' Association are reported. Results of the 1984 survey are compared to two previous surveys, conducted in 1980 and 1982. Topics examined include membership demographics, attendance at national meetings, continuing education needs and preferences, maintaining professional competence, professional issues of importance to readers, and options for improving the usefulness of the Journal of School Health. Several membership trends are discussed and implications for future planning are noted.

Clinical experience with a water activated fiberglass casting material.

One of several new types of synthetic casting material available in the market (Scotchcast™) was evaluated. This system has the advantage of being a fiberglass tape activated by water. In a prospective study of 100 patients whose fractures were casted with this fiberglass tape, we found this system easy to use, light, strong, durable, and water resistant. Our patients developed few complications, most of which were attributable to our inexperience with the system. Cost, while greater than that for the typical plaster cast, was not prohibitive.

Cast-bracing of femoral fractures: experience at emory university hospitals.

At Emory University Hospitals from 1975 to 1979, 110 fractures of the femoral shaft were treated following a femoral fracture protocol with a single component cast-brace and early ambulation. In an effort to reduce the hospitalization and disability time in patients with mid-third and distal-third femoral fractures, a technique of modified Dehne bracing was used in which immediate ambulation was instituted after casting. Prior to initiation of this protocol, these fractures were routinely treated with six to eight weeks of balanced traction, followed by four to six months of cast fixation and a subsequent period of rehabilitation. Complications of the technique occurred in 9% of the patients, with shortening of 2.3 cm in 5%, refractures in 3% and malunion in 1%.This series of patients demonstrates the technical feasibility of a single component cast-brace and early ambulation for fractures of the femoral shaft, which is a great advance in the closed treatment of femoral fractures. Our results show that early cast-bracing using a modified Dehne technique is a viable method of treating fractures of the femoral shaft, with the technique being most effective when applied in the early stages- days one through 28. Indexing terms: cast-bracing, femoral fractures.

Does occupational stereotyping still exist?

We surveyed 113 college students regarding their views of certain occupational stereotypes. Our results indicated that in this population gender was related to the subjects' views of occupations as either male, female, or neutral, and that the father's primary occupation significantly affected the subjects' views of only one occupation--clinical sociologist. The mother's occupational seemed to have no effect.