Biomedical subjects

H A Ahmad

Publications and source records attributed to H A Ahmad.

5 recordsLinked to original sources

PubMed2006

Comparison of forecasting methodologies using egg price as a test case.

Egg price forecasting of shelled eggs is a complex problem. Traditionally, future egg price has been predicted using a combination of regression analysis and experienced-based intuition to build a model, which is then fine-tuned to prevalent market conditions. Even after collecting reliable and expensive data, the subsequent analysis, in many cases, does not produce a high confidence to explain the variations in egg price. In the current project, a different approach using neural networks was used to forecast egg price. A neural network is a mathematical model of an information-processing structure that is loosely based on our present understanding of the working of human brain. An artificial neural network consists of a large number of simple processing elements connected to each other in a network. Urner Barry egg quotes from 1991 to 2002 as well as number of hens, egg storage capacity, and number of eggs placed for hatching from the USDA databases (1993 to 2000) were used to forecast egg price. Regression analysis explained only 37% of the variation in egg price due to the above-mentioned 3 factors. Neural networks, on the other hand, recognize the pattern in previous years' egg prices and then predict the future price more efficiently. The 3 networks used in this research (Ward, back-propagation, and general regression neural networks) fit the forecast line more tightly to the previous year's egg price line than did regression analysis. In the case of general regression neural networks, the R2 value was as high as 60%. Results suggest that neural networks may be a more reliable method of egg price forecasting than simple regression analysis if reliable data are collected and manipulated for such models.

Agriculture↗

PubMed1999

Effect of freezing and microbial growth on myoglobin derivatives of beef.

The effect of freezing and bacterial growth on the discoloration of beef was assessed by measuring myoglobin derivatives myoglobin (MB), oxymyoglobin (MBO(2)), and metmyoglobin (METMB) on the surfaces of fresh and frozen-thawed packaged beef cuts stored at 2 degrees C and analyzed after 0, 3, 6, 9, and 12 days of storage. MB, MBO(2), and METMB concentrations were measured spectrophotometrically. Frozen-thawed beef samples experienced less "blooming" (conversion of MB to MBO(2)) and more rapid discoloration than fresh cuts during storage. By day 3, >20% METMB was formed in the frozen-thawed samples, whereas the fresh samples reached this value after day 6 of storage. The rates of MB oxidation were similar (P > 0.05) for sterile and frozen-thawed inoculated (Pseudomonas fluorescens at a rate of 1.5 colony forming units/cm(2).cm(2) area) samples from day 0 through day 6 of storage. For storage periods of less than a week, bacterial growth is not a major cause of meat discoloration. After day 6, the high bacterial growth rate resulted in a rapid increase in METMB formation. Possible mechanisms for MB oxidation in frozen-thawed beef are suggested.

Animals↗

PubMed1999

Cervicocerebral artery dissections.

OBJECTIVE: To determine the aetiology, frequency, presentation, and outcome of blunt cervicocerebral arterial dissection presentations. PATIENTS AND METHODS: Cases were retrospectively identified through the stroke registers at Royal Melbourne Hospital (a tertiary teaching hospital) and Geelong Hospital (a regional referral centre). Medical notes were then reviewed. RESULTS: A total of 18 cases were identified, with ages ranging from 28 to 53 years. Fifty five per cent of the injuries sustained were to the internal carotid artery and 45% to the vertebral artery. The majority of the injuries were either spontaneous or associated with trivial forces. Other causes included motor vehicle accidents, falls, and cervical manipulations. Fifty five per cent of patients complained of significant neck pain before presentation. Most patients had delayed presentations, with only 39% presenting on the day of the incident. Seventy eight per cent presented with a neurological deficit. Initial computed tomography was normal in 71% of patients. The majority of patients were managed with anticoagulation, and had minimal functional deficit on discharge. Other treatment modalities included surgery (one patient) and thrombolysis (two patients). One patient was managed conservatively. CONCLUSIONS: The incidence of blunt cervicocerebral arterial dissection is unknown; however it is an uncommon diagnosis. The most common presentation is that of a delayed neurological event. Initial brain computed tomography is usually normal. Minimal adverse outcomes at discharge were noted in patients treated with anticoagulation only.

Adult↗

PubMed1997

Econometric feeding and management for first cycle phase two DeKalb Delta hens.

An experiment was conducted to determine the effect of feeding method (constant vs variable) and method of formulation (lysine vs protein) on the performance and profits of first cycle, phase 2 DeKalb Delta hens from 40 to 52 wk of age as influenced by egg and feed prices. Treatments 1 to 5 were formulated based on lysine to contain 0.65 to 0.81% TSAA and fed continuously regardless of feed consumption (constant feeding). Treatments 6 to 10 and 11 to 15 were formulated based on lysine to supply 570 to 650 mg TSAA and protein to supply 580 to 660 mg TSAA per hen per d, respectively, and fed based on feed intake. Dietary TSAA level had no overall significant effect on feed consumption, egg production, egg weight, mortality, or body weight. Hens fed diets using the constant method of feeding had significantly higher egg production, egg weight, egg specific gravity, and body weight than hens fed diets formulated based on lysine or protein using the variable method of feeding. When the treatments in the two variable feeding methods were compared, feed consumption was significantly higher for hens fed diets formulated based on protein whereas egg production, egg weight, egg specific gravity, and body weight were not different. It was concluded that method of formulation (lysine vs protein) and TSAA levels required for maximum profits can vary from at least 570 to 821 mg per hen per d depending upon energy and protein cost.

Animal Feed↗

PubMedDate not supplied

Physiologic responses in healthy Labrador Retrievers during field trial training and competition.

Ten healthy Labrador Retrievers (4 females and 6 males aged 3-6.5 years [mean, 4.5 years]) training with a professional trainer were studied. The dogs were in training during the entire study. Dogs were monitored within 5 minutes after retrieving birds on land and in water on 2 consecutive days during training and on 2 consecutive days at the Atlanta Retriever Club Fall Field Trial. Baseline samples were taken in the morning on a separate day before the dogs were loaded onto a truck. Venous samples were analyzed with a portable blood analyzer. Measurements included hematocrit, sodium, potassium, chloride, blood urea nitrogen (BUN), glucose, lactate, blood pH, Pco2, Po2, HCO3, and TCO2 plus rectal temperature, pulse rate, and respiratory rate. Ambient temperatures were recorded. Distances and times were estimated. Compared to baseline, significant increases occurred in rectal temperature, pulse rate, respiratory rate, chloride, lactate, and pH postexercise (P < .05): sodium, potassium, BUN, Pco2, and TCO2 were significantly decreased postexercise. Blood pH was markedly higher after retrieves on land than after retrieves in water. Estimated mean speeds were 11.4 mph (18.3 km/h) during a triple retrieve on land and 5.6 mph (9.0 km/h) during a retrieve in water. Maximal ambient temperatures were 84-86 degrees F (29-30 degrees C). In summary, Labrador Retrievers training with a professional trainer had evidence of hyperthermia, respiratory alkalosis, hypocapnia, and mild metabolic acidosis monitored within 5 minutes postexercise during training and field trial competition when maximal ambient temperatures were 85 degrees F (29 degrees C). The results provide a baseline against which physiologic responses of dogs with poor performance can be compared.

Animals↗