System and method for forward error correction

A system and method are provided for transferring a packet across a data link. The packet may include a stream of data symbols which is delimited by one or more framing symbols. Corruptions of the framing symbol which result in valid data symbols may be mapped to invalid symbols. If it is desired to transfer one of the valid data symbols that has been mapped to an invalid symbol, the data symbol may be replaced with an unused symbol. At the receiving end, these unused symbols are replaced with the corresponding valid data symbols. The data stream of the packet may be encoded with forward error correction information to detect and correct errors in the data stream

Biosynthesis of Triglyceride and Other Fatty Acyl Esters by Developing Rat Brain

The biosynthesis of triglyceride from 1,2-diglyceride and long-chain acyl coenzyme A (CoA) was studied in developing rat brain. Diglyceride acyltransferase activity was highest in a microsomal fraction, had a neutral pH optimum, and was stimulated by MgCl 2 . Palmitoyl CoA and oleoyl CoA served equally well as acyl donors. The enzyme catalyzed the acylation of both endogenous diglyceride and several naturally occurring and synthetic exogenous diglycerides. In addition, short-chain primary and secondary alcohols were found to be acylated under these conditions. A second acylation system, active at low pH, was found to catalyze esterification of ethanol and cholesterol, but not diglyceride, with free fatty acid. These results demonstrate that brain has the capacity to acylate a wide variety of physiological and nonphysiological hydroxyl compounds.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66158/1/j.1471-4159.1984.tb12842.x.pd

System and method for transferring data on a data link

A system and method are provided for transferring a packet across a data link. The packet may include a stream of data symbols which is delimited by one or more framing symbols. Corruptions of the framing symbol which result in valid data symbols may be mapped to invalid symbols. If it is desired to transfer one of the valid data symbols that has been mapped to an invalid symbol, the data symbol may be replaced with an unused symbol. At the receiving end, these unused symbols are replaced with the corresponding valid data symbols. The data stream of the packet may be encoded with forward error correction information to detect and correct errors in the data stream

Tariff-Rate Quotas : Difficult to model or plain simple?

The difficulty of reliably and accurately incorporating tariffrate quotas (TRQs) into trade models has received a lot of attention in recent years. As a result of the Uruguay Round of GATT negotiations, TRQs replaced an assortment of tariff and nontariff instruments in an effort to standardise trade barriers, and facilitate their future liberalisation. Understanding the nuances of TRQs is now particularly crucial for New Zealand because of the preferential access arrangements that New Zealand has for a number of products in highly protected markets such as the European Union, Japan, and the United States. It has been argued that TRQs are complex instruments and are difficult to model because for any trade flow between two countries, one of three regimes may be applicable : 1. The import quota may not be binding and the within-quota tariff applies; 2. The quota may be binding, the within-quota tariff applies, and a quota rent is created; or 3. Trade occurs over and above the quota, in which case an over-quota tariff applies (although, even in this regime, someone is still able to collect the quota rent on within-quota trade). But even this characterisation, which many claim is too complex to model, is a major simplification of reality. Bilateral preferences are ubiquitous, and such preferences are usually included in the determination of multilateral market access quotas. It is usual, therefore, that the TRQ instrument has several tiers to the quota schedule, plus a number of within and over-quota tariff rates applicable on either a bilateral or a multilateral basis. Further trade liberalisation creates something of a dilemma for New Zealand. Any decrease in over-quota tariffs and/or increase in quota levels potentially reduces the value of quota rents, many of which accrue to New Zealand due to the bilateral preferences. It is important, therefore, that New Zealand trade negotiators understand how much additional trade is required to offset the loss of New Zealands quota rents. Modelling trade in the presence of TRQs is the only way to ascertain this knowledge. The purpose of this paper is to show that complex TRQs can be modelled very easily and precisely. The only catch is that the model must be formulated as a complementarity problem rather than the more conventional linear or nonlinear optimisation problem. The concept will be demonstrated using a simple 3-region, single commodity spatial price equilibrium model of trade.Tariff-rate quota, trade modelling, mathematical programming, complementarity

TOPOGRAPHICAL DISTRIBUTION OF LIPID BIOSYNTHETIC ENZYMES ON PEROXISOMES (MICROBODIES)

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72338/1/j.1749-6632.1982.tb21437.x.pd

Analyzing the Impacts of the Proposed North American Free Trade Agreement on European-North American Dairy Trade Using a Joint-Input, Multi-Product Approach

Mathematical programming models, as typically formulated for international trade applications, may contain certain implied restrictions limiting price responsiveness, intermediate product flows, and arbitrage possibilities. These restrictions are especially important in the case of dairy, and may lead to results which are technically infeasible, or if feasible, not consistent with market equilibrating behavior. The difficulties encountered when modeling dairy trade are described, and an alternative formulation of a spatial model is presented. This formulation allows joint-inputs, multi-products, intermediate markets, and pure transshipment and product substitution forms of arbitrage

Upgrading Aerated Lagoon Effluent with Intermittent Sand Filtration

Intermittent sand filtration was evaluated as a means of upgrading the quality of aerated lagoon effluents to satisfy the requirements of PL 92-500. The aerated lagoon in question treats the wastes from a milk and cheese factory located in northern Utah. The treatment system consists of two diffused air aeration ponds followed by a facultative settling pond, were applied to pilot scale intermittent sand filters with 0.17 mm and 0.40 mm effective size sands. The filters were loaded hydraulically from 0.25 million gallons per acre per day to 1.0 million gallons per acre per day. It was found that sand size has a profound effect on the quality of effluent produced by filtration. Also, sand size was related to the time of operation before plugging occurred. At the levels of application studied, hydraulic loading rate was found to affect BOD removal regardless of influent concentration. However, effluent suspended and volatile suspended solids concentrations reflected changes in influent concentrations regardless of hydraulic loading rate. It was found that filtration of facultative settling pond effluent provided better removals than direct filtration of aerated lagoon effluent using equivalent sand sixes and hydraulic loading rates. It was concluded that intermittent sand filtration was capable of upgrading the effluent from aerated lagoons to meet present and future discharge requirements when effluent from the facultative settling pond was applied to 0.17 mm effective size sand

On-Road Remote Sensing of CO Emissions in the Los Angeles Basin

The University of Denver remote sensor for on-road motor vehicle carbon monoxide emissions was used for eleven days in the Los Angeles Basin in December, 1989. The remote sensor has been incorporated into the 1990 Clean Air Act Amendments as on-road emissions testing . The device measures the CO/CO2 ratio for one-half second behind each vehicle, from which the exhaust %CO is calculated. Vehicles were measured in a mix of many driving modes and speeds ranging from deceleration coming up to a red traffic light through idling in heavy congestion up to accelerations and cruises entering a freeway ramp at highway speeds. The results have been validated by both EPA and CARB blind comparisons. The calculated %CO is analogous to that which would have been measured had the vehicle been equipped with a tailpipe probe. The mass emissions in grams CO per gallon of gasoline used can also be derived. Eight of the days monitored normal urban street driving; three monitored freeway ramps. Over 27,000 valid CO emission measurements were made. When the videotapes had been read and returned to California authorities for matching the license plates, the total number of vehicles both measured and matched with the license plate database was over 16,000. Because of the poor contrast of older California license plates and the sun angles, more plates were readable when the front of the vehicles were imaged. With this arrangement a significant number of vehicles without front plates could not be identified. The license plate matched fleet was 0.15 %CO cleaner (3/4 of year on average newer) than the total fleet. This probably arises because older vehicles have older style plates which are both intrinsically harder to read (lower contrast), and often in poorer condition. Overall for the driving modes and vehicles tested more than fifty percent of the CO was emitted by eleven percent of the vehicles with %CO equal to or greater than five (gross polluters). New vehicles were so clean (gross polluters were less than 1% for the 1989 and 90 model years) that their emissions were almost negligible. The percentage of gross polluters rises from 4% (328 vehicles) of the 83-90 model year vehicles through 17% for the 75-80 model year vehicles to 30% (504 vehicles) of the 1974 and older fleet. If the whole measured fleet could maintain the 1989 and 1990 measured emissions then the total on-road pollution from the 16,000 vehicles measured would decrease more than fivefold. Despite the fact that the new vehicles are on average clean, the dirtiest 20% of the one year old fleet was dirtier than the cleanest 20% of any model years regardless of age. Because old vehicles are not numerous, and most new vehicles are low emitters, most of the carbon monoxide came from emissions of the dirtiest 20% of the vehicles with model years between 1976 and 1988. An analysis of the data indicates that a conservative upper limit of fifteen percent of the measured CO emissions arises from vehicles in either a cold start or an off-cycle acceleration mode. Forty three percent of the fleet of 77 vehicles measured four or more times were always in the clean (\u3c1 %CO) category. These emit 4% of the total CO from all 77 vehicles. One quarter of the fleet of 77 showed emissions consistently between one and five percent CO. These vehicles emitted 18% of the CO An additional 25% of the fleet were over the five percent CO cut point at least twice. These vehicles emitted 70% of the emissions. Only a small fraction (5 vehicles, 7% of the fleet of 77 vehicles) jumped into the high category only once. The emissions variability observed in this data set is similar to the emissions variability observed when vehicles are repetitively subjected to conventional I/M testing. These results imply that an inspection and maintenance program incorporating remote sensing, which targets gross polluters with multiple violations, has the potential to identify a significant fraction of the CO emissions while inconveniencing only a small fraction of the vehicle owners. Our analysis concludes that on-road remote sensing as a component of an I/M program has the advantages of being representative of the on-road emissions of the vehicle in question, being an emissions test which is almost impossible to circumvent, and incorporates a fairness factor such that the more a vehicle is driven, the more frequently it will be tested. When age related factors are eliminated the findings in California are essentially identical to findings from on-road CO studies of large fleets of vehicles in Denver, Chicago and Toronto. Forty-seven vehicles out of a fleet of 387 vehicles registered as diesels show emissions greater than 2%CO. Of these vehicles, thirty-nine are 1975-84 General Motors vehicles. The vehicles are such high emitters that the only sub-fleet found to be dirtier are 1955-1970 vehicles. Three lines of evidence point to the conclusion that more than half of the vehicles listed in this category are not diesel powered and are incorrectly registered thereby avoiding the California Smog-Check program. There were differences in average CO emissions between the sites measured, and to a lesser extent between different days at the same sites. To aid in understanding this phenomenon, all remote sensing data available at the University of Denver from a variety of US cities with altitudes lower than 7,000 ft were analyzed in terms of hourly average CO emissions compared to hourly average fleet age. From this analysis a linear model was developed which demonstrated that almost all of the observed differences could be accounted for by differences in average age. This results because of the previously shown influence of the gross polluters which increases with fleet age. Smaller, load induced average emission increases between an uphill but slow cruise-mode freeway off-ramp and a flat but high speed acceleration on-ramp were discernable after the age differences had been eliminated. The linear model predicts average %CO for all fleets measured in the USA to better than 0.5 %CO with a knowledge of only the average fleet age. The important conclusions are that a few vehicles (gross polluters) emit most of the CO A few vehicles are always measured in the gross polluter category, a few are frequently in that category, and most are never gross polluters. The fraction of gross polluters increases from one in one hundred new vehicles up to one in three old ones. Although new vehicle standards and technology changed from the early seventies to the early eighties, no sharp breaks are observed for the transition model years. The evidence suggests that on-road CO emissions increase linearly with average age of the fleet, and that the linear increase is dominated by the steady increase in the fraction of gross polluters with age. This increase with age appears to be caused in large part by improper (in some cases illegal) maintenance practices

Sympathetic nervous regulation of calcium and action potential alternans in the intact heart

Rationale: Arrhythmogenic cardiac alternans are thought to be an important determinant for the initiation of ventricular fibrillation. There is limited information on the effects of sympathetic nerve stimulation (SNS) on alternans in the intact heart and the conclusions of existing studies, focused on investigating electrical alternans, are conflicted. Meanwhile, several lines of evidence implicate instabilities in Ca handling, not electrical restitution, as the primary mechanism underpinning alternans. Despite this, there have been no studies on Ca alternans and SNS in the intact heart. The present study sought to address this, by application of voltage and Ca optical mapping for the simultaneous study of APD and Ca alternans in the intact guinea pig heart during direct SNS. Objective: To determine the effects of SNS on APD and Ca alternans in the intact guinea pig heart and to examine the mechanism(s) by which the effects of SNS are mediated. Methods and Results: Studies utilized simultaneous voltage and Ca optical mapping in isolated guinea pig hearts with intact innervation. Alternans were induced using a rapid dynamic pacing protocol. SNS was associated with rate-independent shortening of action potential duration (APD) and the suppression of APD and Ca alternans, as indicated by a shift in the alternans threshold to faster pacing rates. Qualitatively similar results were observed with exogenous noradrenaline perfusion. In co ntrast with previous reports, both SNS and noradrenaline acted to flatten the slope of the electrical restitution curve. Pharmacological block of the slow delayed rectifying potassium current (I Ks ), sufficient to abolish I Ks -mediated APD-adaptation, partially reversed the effects of SNS on pacing-induced alternans. Treatment with cyclopiazonic acid, an inhibitor of the sarco(endo)plasmic reticulum ATPase, had opposite effects to that of SNS, acting to increase susceptibility to alternans, and suggesting that accelerated Ca reuptake into the sarcoplasmic reticulum is a major mechanism by which SNS suppresses alternans in the guinea pig heart. Conclusions: SNS suppresses calcium and action potential alternans in the intact guinea pig heart by an action mediated through accelerated Ca handling and via increased I Ks