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Test catches defective parts. Traditional DFT makes test-related activities more cost effective. Debug and diagnosis discovers why a design or part did not work. Yield relates to how many good parts can be shipped thus how many dollars can be received. As one would expect, all these areas are related. The issue becomes: Can information from one operation be geared to better another? This panel specifically considers how test/ DFT can aid in debug & diagnosis. The discussion is then extended to capture the impact on yield management in riskier contemporary and future processes. Over the past few decades, each of the above domains have gone through cycles of research, development, maturity and overhaul to adapt to changes in the process & product environment. In fact, because increasing degrees of uncertainty is introduced with modern nanometer processes, debug & diagnosis and yield management are becoming more recognized and valued portions of the product creation flow. To forward this, test and DFT functions are experiencing re-development. In building, executing and sustaining a competence, key issues include time & information. That is, the problem must be understood, solved in for the short term and solved for the long term. In addition, solution scope must be properly framed and, if possible, adaptable to unexpected changes in the process and tooling environments. It is well recognized that information availability and access are pillars of a debug/ diagnosis solution. DFT structures, design automation tooling, test programs, ATE applications and physical failure analysis are means to a bulk of this data. The follow through is the assimilation of this data into a yield management and test quality system. As the topic is broad, panel of test experts will focus on practical experiences concerning the use of test, crafted DFT or test environments to facilitate debug and diagnosis. Precise developments in tying debug/ diagnosis to yield management will also be discussed.

Historically, design margin and defects have been viewed as different topics, one part of design and the other part of test. Shrinking process geometries are making the two part of a continuum. This paper discusses the leakage and delay behavior associated with classic resistive defects and compares it with transistor variation due to lithography

Design for Manufacturability (DFM) is becoming increasingly important as process geometries shrink. The System-on-Chip business model requires high quality, high yielding IP. This paper shows how DFM and DFY are integrated as part of IP delivery, using a set of metrics to identify and fix yield limiters without compromising power, area or performance.

As device geometries continue to shrink, single event upsets are becoming of concern to a wider spectrum of system designers. These "soft errors" can be a nuisance or catastrophic, depending on the application, but they must be understood and their effects budgeted for. Ultimately, experimental measurement is needed to quantify soft error rates, but after-the-fact measurement is too late to make changes. This paper shows a methodology that can be used to estimate the soft error properties of individual IP blocks by using a combination of critical charge calculations and experimental data.

Aggressive performance and power goals for coming process generations are forcing rethinking of some of the basic assumptions of CMOS transistors, and leading to innovative approaches such as strained silicon and metal gates. These methods have implications for the design of standard cells, embedded memories, and other library components. This paper examines these new trends and shows how they affect the design of these components, and by extension, the systems-on-chip built from them.

The System-on-Chip (SoC) model has evolved as a method to help design productivity keep pace with the ever-increasing capabilities of silicon manufacturing. The SoC design style employs design reuse, and reuse allows IP to be shared among many designs and across companies. The combination of SoC and the fabless semiconductor model have resulted in the disaggregating of IC manufacturing, leading to the specialization model shown in Figure 1. Where all these functions historically existed only within vertically integrated companies, now horizontally specialized companies provide manufacturing capability and supply IP.

Defect-based testing for digital logic concentrates primarily on methods of test application, including for example at-speed structural tests and IDDQ testing. In contrast, defect-based testing for memory concentrates on defect analysis of key parts of the layout and the development of application-independent patterns that will test for likely failures. Testing hundreds of embedded memories on today's SoC designs requires a combination of these approaches in order to assure high quality. Historically, DBT has been enabled in large vertically structured companies that included design, test development, and manufacturing. Many of today's SoCs are built with a different approach, the "customer-owned tooling" (COT) model, where a fables design customer builds a chip with third party IP, including memories, manufactures it through a foundry, and tests it at a separate test house. This complex supply chain cannot be ignored when developing a test solution.

Today's system on chip (SoC) designs can use hundreds of embedded memories. Most of these are created by automated generators, which must produce a wide variety of configurations while retaining essential capabilities in area, performance, power and testability. Redundancy, repair, and test issues in the context of memory generators are more complex than they are in the context of individual embedded memories, or even internally developed memories.

This paper shows how process variation affects memory margin and performance, and shows that in some cases additional redundancy capability can be used to recover yield due to process variation in addition to yield recovery for defects.

Summary form only given, as follows. Successful product development is based on successful design flows and methodology. This session explores three key and often-overlooked aspects of these flows: integrating a working system-on-chip from a diverse set of IP, packaging and the silicon/PCB interface, and finally manufacturing test. Discovering the dependencies that exist among the decisions and objectives at each stage of the flow can drive global optimization. The speakers will discuss the tasks, decisions and objectives of their portion of the flow. These are compared for apparent and non-obvious optimization opportunities. The discussion continues in a panel format that invites the audience to further explore the topic. The following position papers give insight into the session presenters? views on these topics. The presenters are: Tarmo Ruotsalainen, Nokia Mobile Phones Ltd, Finland; Sanjay Dandia, Philips Assembly and Test Operation, USA; and Bill Eklow, Cisco Systems, USA.

Background: In laboratories employing 'front-line' sensitive thyroid-stimulating hormone (TSH) measurement, it is generally accepted that a fully suppressed serum TSH concentration (third-generation assay) alongside normal serum concentrations of free thyroid hormones indicates subclinical hyperthyroidism. However, other explanations are often provided for low but detectable serum TSH concentrations, such as drug effects or non-thyroidal illness. Methods: We investigated 25 consecutive ambulant individuals, identified over an 18-month period as having low but not fully suppressed TSH concentrations (third-generation assay; sensitivity 0.003 mIU/L) with additional free thyroxine (T4), free tri-iodothyronine (T3) and thyroid microsomal antibody estimations and thyroid isotope scanning (technetium). Results: Concentrations of serum hormones (median, inter-quartile range) were: TSH, 0.23, 0.17-0.26 mIU/L (reference range 0.34-5.6 mIU/L); free T4, 14.6, 10.6- 17.6 pmol/L (reference range 10-25 pmol/L); free T3, 6.1, 5.7-6.6 pmol/L (reference range 4.5-7.5 pmol/L). Thyroid antibodies were negative in all but one individual. On isotope scanning, nine individuals had hot nodules and ten individuals had multinodular goitres (MNG). Of the six with normal scans, ultrasound scanning showed a definite MNG ( n = 1) and early MNG ( n = 2). Conclusions: A low but detectable serum TSH concentration, obtained using a third-generation assay, found in an ambulant individual, is frequently a pointer to underlying thyroid disease.

The operating principle and application of the Mach-Zehnder interferometer and its use as a nonintrusive electric-field measuring device are discussed. The methods and technical difficulties in the construction of these sensors are explained, and some of the results are presented. The device uses a microantenna that allows collection of charges close to the waveguide. As a result, the device is sensitive to a small variation in external electric fields. In principle, the length of this antenna can be adjusted for a specific radiation measurement. >

The EASE model is currently being used for a review of exposure to zinc compounds and there is concern about whether the predicted dermal exposures are reliable. The work reported here contains details of actual dermal zinc exposure measurements, collected from a wide range of exposure scenarios, and these are compared with the relevant EASE predictions. Dermal exposure measurements were collected using a swab sampling method validated using human volunteers. Samples were also collected from a control group to determine natural background dermal zinc levels. The assessments of dermal exposure to zinc were carried out in two phases. Preliminary assessments were carried out in a galvanising factory and a zinc oxide manufacturing plant. These were followed up with more detailed assessments in five other factories. These included a galvanising plant, a zinc metal refinery and three different factories producing zinc chemical products. The different exposure scenarios were classified in terms of the EASE categories and then compared with the predicted exposures. The tasks fell into three different EASE exposure ranges or ‘endpoints’. It was apparent that EASE consistently overestimated exposure, generally by about one order of magnitude. However, the EASE predictions increased in line with the measured exposures. It is clear that further work is necessary to refine the EASE model to improve its reliability in these circumstances. With certain exceptions, the use of protective gloves in the workplaces investigated in this study was not considered an important factor in this exposure assessment. This was because the gloves themselves and the method of working were not designed to control dermal exposures. Hence, it is concluded that they provided only limited protection against dermal exposure to zinc.

Modeling of disease pathogenesis and immunity often is carried out in large animals that are natural targets for pathogens of human or economic relevance. Although murine mAbs are a valuable tool in identifying certain host/pathogen interactions, progress in comparative immunology would be enhanced by the use of mAbs isolated from the host species. Such antibodies would reflect an authentic host immune response to infection or vaccination, and as they are host derived, would allow the application ofin vivoexperiments that previously have been unrealizable in large animals because of induction of an antispecies immune response. The advent of antibody phage display technology provides a way of producing host-derived mAbs in animals where the molecular genetics of Ig formation are known. Exploiting recent advances in the molecular immunology of cattle, we report here the design of an optimized phage display vector, pComBov, for the construction of combinatorial libraries of bovine Ig antigen-binding fragments (Fab) of native sequence. By using this system, we initially have generated and characterized a panel of bovine mAbs against a model antigen glutathioneS-transferase. The isolated mAbs showed features typical of bovine Igs and recognized glutathioneS-transferase with high specificity in ELISA and by Western blotting. The pComBov expression system can be readily adapted for the preparation of libraries from related ruminant species and advances the use of monoclonal reagents derived in this way for comparative studies in animals of economic importance.

External beam radiotherapy in advanced neuroblastoma is limited by the volume of normal radiosensitive tissues included in the radiation field. Limitations to external radiation are the late effects to these tissues. Intraoperative radiotherapy (IORT) delivers a single high-radiation dose to a tumor while displacing normal tissues that would have been included in an external field. Standard external radiotherapy can still be done after "boost" IORT.Eight advanced-stage neuroblastoma patients who received IORT as part of their multimodality therapy were reviewed to identify the impact of IORT on operative time, complications, and tumor control in the treatment field. The IORT was accomplished by patient transport from the OR to the radiation therapy suite; these were separated by three floors.IORT added 30-75 min to the operative procedure. Tumors in the resection/IORT fields showed no evidence of disease (one), stable tumor size (six), and tumor recurrence (one). Two complications were identified: a urinary fistula and CO2 retention, which was detected and corrected before the IORT. Neither of these complications was related to the IORT. Two patients who had subsequent tumor resection after IORT demonstrated tumor differentiation to ganglioneuromatous tissue.IORT usually can be completed in less than an hour. No IORT-associated complications were identified. IORT along with maximal tumor resection, external radiation, and chemotherapy enhances local tumor control.

The presence of abdominal wall scarring and intra-abdominal adhesions following prior abdominal surgery has been proposed as a relative contraindication to the performance of laparoscopic cholecystectomy. The impact of prior abdominal surgery on the management of symptomatic gall bladder disease was retrospectively reviewed. Three groups were evaluated: open, laparoscopic, and laparoscopic converted to open cholecystectomy. Clinical factors analyzed included lengths of operative time, postoperative hospitalization stay, medical risk (ASA Classification), and postoperative complications. In addition, factors contributing to the conversion from a laparoscopic to open procedure were evaluated to determine the impact of prior surgery on conversion. The records of 504 consecutive patients undergoing open and laparoscopic cholecystectomy were reviewed. Individuals having additional intra-abdominal procedures were excluded. A total of 175 patients were identified who had prior abdominal surgery and underwent a cholecystectomy. In patients requiring cholecystectomy who have had prior abdominal surgery, the following observations can be made regarding laparoscopic cholecystectomy: 1) The operative time is less compared to open cholecystectomy. 2) The advantage of a shorter postoperative stay is realized. 3) The conversion rate (7/158) is low. Five of the seven conversions were due to the dense adhesion that prevented safe needle/trocar placement. 4) The complication rate is not increased. 5) The successful completion rate of laparoscopic cholecystectomy following prior intra-abdominal surgery (95.6%) is high.

The Rapunzel Syndrome, a rare manifestation of trichobezoar, occurs when bolus gastrointestinal obstruction is produced by an unusual trichobezoar with a long tail that extends to or beyond the ileocaecal valve. A five-year-old Jamaican girl presented with this abnormality and was found at laparotomy also to have an ileo-ileal intussusception. For the Rapunzel Syndrome, we recommend bezoar extraction at laparotomy via multiple enterotomies. In addition, psychiatric evaluation and therapy is essential due to the commonly associated finding of underlying emotional stress.

Even though the incidence of gastric carcinoma is decreasing, the prognosis remains poor. A review of 88 patients with advanced gastric cancer was evaluated by univariate and multivariate analysis to determine prognostic factors. Univariate analysis showed that both "curative" resection (P = 0.006) and adjuvant chemotherapy (P = 0.02) were important therapy variables. These factors were not independent when evaluated by multivariate analysis. However, when they were combined and re-evaluated by multivariate analysis, the combination of "curative" surgery and adjuvant chemotherapy significantly improved survival in advanced gastric cancer (P = 0.04).

Laparoscopic cholecystectomy has achieved wide acceptance as the preferred treatment for symptomatic gallbladder disease. Yet there are alarming reports of iatrogenic bile duct injuries. To establish a comparison standard, the incidence of iatrogenic bile duct injury during conventional cholecystectomy has to be known. A single institutional retrospective review of 1,617 consecutive open cholecystectomies between 1980 and 1989 was performed. Eight patients (0.49%) sustained iatrogenic bile duct injury in this study. Inflammation, anatomic variation, or both were contributing factors in all injuries. Operative cholangiography identified the injury at the initial operation in three patients. Treatment consisted of either primary ductal repair, ductal repair over a stent, or ductal-enteric anastomosis. There were no late complications after surgery (follow-up 26 to 97 months; mean 50.9 months). The implications for laparoscopic cholecystectomy are apparent. Iatrogenic bile duct injuries are associated with acute inflammation and/or variant ductal anatomy; routine operative cholangiography assumes increased importance; and immediate repair of the injury minimizes long-term complications.

The most common mastectomy-associated complication is seroma formation. Seromas can be associated with other more serious complications such as skin flap necrosis, delayed wound healing, infection, and lymphedema. The flap tacking procedure that closes the axillary fossa dead space and tacks the mastectomy flaps to the chest wall has been suggested as one potential technique to reduce the incidence of postmastectomy seromas. This institution-wide study of modified radical mastectomies demonstrated a significant decrease (P0.0381) in the incidence of seroma when flap tacking was performed. Women who developed a seroma, compared to those who did not, averaged nearly twice as any office visits in the first 2 months after the operation. Distribution of office visits between the seroma patients and nonseroma patients was significant (P0.0001). When practiced by several surgeons, the flap tacking procedure 1) reduces postmastectomy seromas and 2) reduces the amount of postoperative patient office visits and care.

Introduction: Enhanced Recovery Programs (EPR) have been shown to reduce mortality, morbidity and length of stay. Can similar results be produced in tertiary centres with the presence of complex colorectal cases? Method: 102 patients were prospectively analysed with a power calculation of 34 being established prior to commencement of the study. The average age was 66.6 (male: female ratio of 1:1). Data collection included demographics, operative procedure, pain scores, POSSUM scores, American Society of Anaesthiology (ASA) scores, and discharge times. All complications were documented. Results: 83 cases were open procedures and 19 laparoscopically, (3 were converted intra-operatively). The majority were anterior resection (47, [46.1%]) and right hemicolectomies (32, [31.3%]). The average overall discharge time was 11.75 days compared to 15.11 (p < 0.001) prior to commencement of the study in 2005. Anterior resections and subtotal colectomies (14.3 and 13.7 days respectively) had significantly longer lengths of stay compared to right hemicolectomies (10.7 days) [p < 0.001]. 56% patients were ASA grade 3 & 4 (50% and 6% respectively). A clear correlation with increasing ASA and discharge time was demonstrated (ANOVA p = 0.0004) with significant exponential rise with ASA greater than 2. POSSUM scoring demonstrated a positive correlation with prolonged hospital stay with increasing scores having worse discharge time. Conclusion: In the presence of complex major surgery and tertiary centre referrals an ERP is feasible producing an average saving of 3.36 days. The benefit is however less with increasing ASA and POSSUM Scores. It however still produced an average economic bed stay saving cost of $3700 per patient stay.

• Preliminary data using B72.3 murine monoclonal antibody labeled with iodine 125 suggested that both clinically apparent as well as occult sites of colorectal cancer could be identified intraoperatively using a hand-held gamma detecting probe. We report the preliminary data of a multicenter trial of this approach in patients with primary or recurrent colorectal cancer. One hundred four patients with primary, suspected, or known recurrent colorectal cancer received an intravenous infusion of 1 mg of B72.3 monoclonal antibody radiolabeled with 7.4×10 Bq of iodine 125. Twenty-six patients with primary colorectal cancer and 72 patients with recurrent colorectal cancer were examined. Using the gamma detecting probe, 78% of the patients had localization of the antibody in their tumor; this included 75% of primary tumor sites and 63% of all recurrent tumor sites; 9.2% of all tumor sites identified represented occult sites detected only with the gamma detecting probe. The overall sensitivity was 77% and a predictive value of a positive detection was 78%. A total of 30 occult sites in 26 patients were identified. In patients with recurrent cancer, the antibody study provided unique data that precluded resection in 10 patients, and in another eight patients it extended the potentially curative procedure. ( Arch Surg . 1991;126:349-352)

Tumor radioimmune detection as presently practiced utilizes a gamma scintillation camera to image tumors. A major clinical limitation is the inability to detect tumors smaller than 2 cm. This limitation is due in part to the inverse square law which states: the number of detected radioactive counts is inversely proportional to the square of the distance separating a radioactive source from the detecting device. A hand-held gamma-detecting probe (GDP) suitable for intraoperative use has been developed. The GDP can be placed near radioactive tumors and take advantage of the inverse square law in a way not possible with external scanning cameras. The use of radiolabeled baboon carcinoembryonic antigen (CEA)-specific antisera produced increased tumor isotope localization in CEA-producing tumors compared to the injection of nonspecific antisera. Tumor isotope-antisera localization was not influenced by tumor volume or time since tumor implantation. The GDP probe counts demonstrated a high degree of correlation with gamma well tissue counts. The probe was able to detect preferential tumor localization in doses lower than could be detected with external scintillation cameras.

The detection of tumors with radiolabeled antibodies against CEA is possible; however, current nuclear medicine scanning cameras rarely detect tumors smaller than 2 cm in diameter. One of the limitations to tumor detection is the inability to place a detecting camera near a deeply seated intra-abdominal tumor. A hand-held gamma-detecting probe, suitable for intraoperative use, was designed to locate radioactive tumors. Experimental work with CEA-producing colon tumor xenografts in nude mice suggests this probe is more sensitive than external scanners in detecting small tumors. A case report documents the clinical use of this new intraoperative probe.

Robert Aitken is a principal research scientist in Courtaulds Research Division. He studied chemistry at the University of St. Andrews and graduated in 1964, when he joined the Development Fibres and Viscose Laboratory at Coventry. He has taken part in the development of a variety of viscose fibre types, including crimped, polynosic and modal fibres. Other posts have included pilot-plant manager, managing a cigarette factory for tobacco substitute, and leading the research and development for Courtaulds' elastomeric fibre plant. He is currently working on the development of new end uses for viscose including enhanced dyeing, flame-resistant products and non-wovens. Although it is one of the earliest of man-made fibres, viscose rayon remains of great interest. This is because it is made from a renewable resource, and because the fibre-making process is so adaptable. Novel types have been made, and continue to be made, to meet the changing demands of the textile market. Recent developments include the new class of high-strength viscose fibres with tenacities of 25 to 28 cN/tex, the super-inflated cellulosic SI fibre which has a very high absorbency without containing any additives, the hollow circular cross-section fibre Viloft for blending with cotton or polyester, and a new generation of enhanced-dyeing fibres.

Pulmonary cellular responses in C57BL/6 mice exposed to Schistosoma mansoni have been investigated by sampling cells from the respiratory airways with bronchoalveolar lavage. Mice exposed to cercariae attenuated with 20 krad gamma-radiation developed stronger and more persistent pulmonary leukocytic responses than animals exposed to equal numbers of normal parasites. Although vaccination with irradiated cercariae also stimulated T cell responses of greater magnitude and duration than normal infection, the lymphocytic infiltrate elicited by each regimen did not differ substantially in its composition, 5 wk after exposure. Studies with cercariae attenuated by different treatments established that a link exists between the recruitment of leukocytes to the lungs of vaccinated mice and resistance to reinfection. There was a strong association between pulmonary leukocytic responses and the elimination of challenge infections by vaccinated mice. Animals exposed to irradiated cercariae of S. mansoni were resistant to homologous challenge infection but were not protected against Schistosoma margrebowiei. Homologous challenge of vaccinated mice stimulated anamnestic leukocytic and T lymphocytic responses in the lungs, 2 wk postinfection, but exposure of immunized animals to the heterologous species failed to trigger an expansion in these populations of cells. Our studies indicate that pulmonary leukocytes and T lymphocytes are intimately involved in the mechanism of vaccine-induced resistance to S. mansoni. It remains unclear whether these populations of cells initiate protective inflammatory reactions against challenge parasites in the lungs, or accumulate in response to the activation of the protective mechanism by other means.

Diets containing varying levels of fish meal (3–19%) were fed to broiler chickens representing male and female birds of four different genotypes. After slaughter and processing, sample birds were roasted without seasoning, and portions of skin, breast meat and thigh meat were submitted to a taste panel of nine judges. Each portion was tested by asking one of the judges to identify it when it was presented along with two comparable portions taken from a control bird. There were 720 such triangle tests, comprised of six replicate tests within each of the 120 subclasses denned by genotype, sex, nutritional treatment and type of tissue.Flavor differences between birds fed 3% and 9% fish meal were detected with a frequency which was highly significant in skin and breast meat, but in thigh meat there was no significant effect on flavor until the level of fish meal reached 14%. Neither sex nor genotype had any influence on the detection of flavor differences. The practical significance of these findings is discussed.

CURRENT interest in the inclusion of ascorbic acid in laying rations was stimulated by the report of Thornton and Moreng (1958) that dietary ascorbic acid reduced the decline of egg shell quality experienced under high environmental temperatures. The earlier negative results of Heywang and Kemmerer (1955) might be explained by their higher (20 times) level of ascorbic acid supplementation. That high environmental temperature is detrimental to egg shell quality has been demonstrated frequently (Bennion and Warren, 1933; Warren and Schnepel, 1940; Wilhelm, 1940; and others). Why this is so has not been clearly indicated. Conrad (1939) and later Mueller (1959), demonstrated that high temperatures depressed serum calcium but Mueller also found a negative correlation between egg shell thickness and serum calcium level. Thornton and Moreng (1959) believe thyroid function is depressed by high temperatures and stimulated by ascorbic acid as they observed that oxygen consumption increased and egg shell quality …

IN maritime areas where fish meal is the cheapest source of protein, it would be desirable to use it exclusively as the protein supplement in poultry rations. This is quite feasible in laying diets (Smith and Chancey, 1967) where the high mineral content of the fish meal is an advantage and the level required is not high enough to cause concern about off flavors in the edible products. Broiler diets require much higher levels of protein than laying diets. The exclusive use of fish meal to supply this extra protein can bring mineral levels well above optimum, and cause concern about the possibility of undesirable flavors in the meat. Hardin et al. (1964) fed diets containing 5, 10 and 15% of a solvent extracted 70% protein fish meal to broilers. They found no significant differences in growth rate on the three diets. Waldroup et al. (1965) replaced 25, 50, 75…

THE REPORT of Scott et al. (1947) has stimulated a great deal of work on the utilization of high energy rations for the production of broilers. Hill and Dansky (1950) indicated a relationship between the level of protein and productive energy in the diet of chicks. These authors observed a reduced growth rate in chicks fed a diet containing less than 20% protein but high in productive energy. Normal growth was obtained when the level of productive energy was reduced. Combs and Romoser (1955) concluded that the growth rate in broilers to 7 weeks of age was not affected until more than 41.5–42.0 Calories of productive energy per pound of feed were supplied for each pound of protein. The influence of different productive energy to protein ratios upon the growth and feed efficiency of chicks has been reported by many workers. Among these, Vondell et al. (1958) concluded that …

Diets varying in protein content from 10.9 to 16.7 per cent were fed over a 336-day laying period to hens in both floor pens and individual laying cages. All rations were approximately iso-caloric, the mean productive energy value being 825 Calories per pound. Each ration was fed to 200–240 hens in four floor pens and to 90–96 hens in individual cages.A crude protein level of 13 per cent of the diet proved adequate for egg production, but egg weights and body weights were improved when the dietary protein was increased. Egg shell quality was highest on low protein diets. Interior egg quality was not affected by the protein level in the diet.On comparable diets, birds in individual laying cages laid fewer eggs and consumed less feed than birds in floor pens. Caged birds were heavier in body weight and laid heavier eggs with thicker shells than their counterparts in floor pens. The criteria employed in the measurement of interior egg quality showed no differences between the cage and pen environments, nor did there appear to be any differences in protein requirements between the two environments.

Experiments were conducted in 3 successive years to measure the effect on the performance of laying hens of restricting feed during the rearing period on range. About 1100 birds were reared and carried through a laying year in each experiment. Feed restriction was 72, 76 and 63 per cent of full feed for the test groups in Experiments 1, 2, and 3 respectively. All birds were full-fed in the laying house.Feed restriction changed the pattern of egg production, in that the restricted birds came into production later but subsequently laid at a higher rate than their full-fed counterparts. After 318 and 322 days in production the restricted birds in Experiments 1 and 2 respectively had overcome the disadvantage of a late start (7 and 14 days) and produced as many eggs as the full-fed birds. In Experiment 3, the restricted birds were held back 20 days, and after 315 days in production were still significantly behind in number of eggs produced.The restricted birds in the three experiments consumed an average of 0.17 pounds less feed per dozen eggs over the combined rearing and laying periods This amounts to a saving of 3 pounds of feed per bird, since the mean egg production of the restricted groups was 18 dozen eggs per bird.Early egg size was markedly increased by feed restriction and egg weights taken later in the year (after 3 months in production) remained slightly higher for the restricted groups. Albumin score for eggs from the restricted birds was better in all tests, but not significantly so in any given experiment. Specific gravity of the eggs was not influenced by feed restriction.Mortality on range and in the laying house was not affected by feed restriction on range. Body weight at housing time was much lower for the restricted birds but was not significantly lower at the end of the laying year.

Inter- and intralaboratory variation in amino acid composition of casein, soy flour, and fish flour was examined for 5 cooperating laboratories, utilizing ion exchange chromatographic analyses for amino acids. Duplicate analyses within laboratories exhibited coefficients of variation of 3.7 to 4.4%. Hydrolysis was observed to affect amino acid recoveries to a significant degree, with some amino acids affected to greater extents than others. Laboratories utilizing Moore-Stein type analytical procedures did not appear to be more precise than those using the Piez-Morris method. Adjustment of data to constant total recovery values reduced interlaboratory variation considerably and suggested that recovery constants may be of value in comparing data from different laboratories. Results indicated that different laboratories employing varying analytical procedures may produce practically identical results from a standard sample, although variation may be observed due to characteristics of a specific system. Most variation in results was likely due to sample manipulations rather than to analysis per se.

The mechanism of flow of air and water through packed glass fibres has been studied. Pressure drops and liquid hold ups were measured as a function of gas and liquid flow rates and the packing characteristics. It has been found that the pressure difference measured is dependent upon the history of previous gas and liquid flow rates in the bed. The liquid hold up is defined entirely by the gas and liquid flow rates. An analysis of the flow mechanism shows that the capillary forces interact with the fluid pressures in the bed. For example an increase in gas flow rate followed by a reduction to the same flow rate has been shown to reduce the resistance of the bed to gas flow even though the liquid flow rate is unchanged. A measure of the irreversibility of the flow operation is suggested.