Minimum Acceptable Value Research Articles

Haemoglobin adjustments to define anaemia

To provide researchers with an unambiguous definition of anaemia using haemoglobin. Review of recommendations by expert groups and review of the literature. This report provides an unambiguous approach to haemoglobin adjustments to define anaemia using international criteria. When determining anaemia using haemoglobin, it is important to account for pregnancy, altitude, cigarette smoking, and possibly ethnicity after removing unlikely values. These haemoglobin adjustments are presented. Recommendations for defining extreme haemoglobin values and for reporting anaemia and haemoglobin results are provided, and software programs to determine anaemia are described.

Methodological and Statistical Problems in Uvulopalatopharyngoplasty Research

To review the published literature on uvulopalatopharyngoplasty (UPPP) and assess the methodological quality of the research and compare it with a similar article published in 1995; and to determine what, if any, improvement in the methodological quality of the research resulted during the ensuing 10 years. Methodological and statistical evaluation of the published literature on UPPP. Thirty articles representing the clinical studies on UPPP and related procedures written from January 1996 to August 2005 were reviewed. Only articles reporting polysomnography data were included. Overall, the articles demonstrated fair methodological and statistical quality. Compared with the previous review by Schechtman et al, there was a slight increase in the number of articles that discussed statistical power and reported confidence intervals. There were increases in the mean sample size, the percentage of randomized controlled studies, the number of end points, and the use of validated subjective outcome measures; longer mean follow-up time; and more complete reporting of age and sex information. There was no increase in the percentage of published studies that used a prospective study design. None of the studies that required minimum acceptable baseline values of objective sleep parameter measures for enrollment indicated the use of separate screening and baseline assessments. There were 7 different definitions of sleep apnea and 17 different definitions of success in treatment. There has been an overall improvement in the quality of the articles published on UPPP since 1995. Several areas still need improvement: use of more prospective studies, decrease in number of end points, use of separate screening and baseline assessments, and consensus in the definitions of sleep apnea and success.

A simplified approach to predict part temperature and minimum “safe” cycle time

AbstractThe largest component of the injection molding cycle is the cooling time. Thus it is highly desirable, to be able to predict what its minimum acceptable value can be. This is becoming even more important with increased competition from regions where the labor cost is low. In an injection molding operation, the mold thermal state changes from its initial value until a quasi steady state is reached. The minimum required cooling time increases with continuous molding until a steady state value is achieved. Improving the mold thermal design will decrease the cooling time thus reducing total cycle time. The overall goal of this work is to develop a simple reliable method to predict a minimum safe cycle time for steady production. In this article, we discuss software capable of simulating the thermal state of the part and mold for multiple injection molding cycles while balancing simulation time with results accuracy. Three case studies are presented, one done in our labs and two on‐site at an automotive manufacturing facility. The three case studies are used to evaluate the ability of the software to predict part surface temperature for continuous molding. We also discuss how this software can be used as the basis to establish the minimum safe cycle time. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers

Estimates of uncertainty in the prediction of past climatic variables

Fitting a regression line to a set of measurements to investigate the relationship between a proxy estimate of past climate and known climatic parameters is a routine procedure. It is generally accepted that the higher the correlation between parameters, the more reliable the reconstruction. However, there is a lack of published work upon what correlation is the minimum acceptable value. Simulated data was used to demonstrate that the relationship between proxy values and the climatic data are adversely affected by falling correlation, to the point where, in a training set consisting of 100 pairs of temperature and tree-ring proxies, the mean 95% confidence interval width for the reconstructed temperature exceeds the total range of temperatures in the training set at or below r = 0.65. This correlation is typical of that used in many climate-proxy reconstructions, and it suggests that understanding of past climate variability may be somewhat constrained.

Validation of the reflux disease questionnaire for an Italian population of patients with gastroesophageal reflux disease

The reflux disease questionnaire (RDQ) is a very simple questionnaire based on only 12 questions that can be answered and evaluated quickly in a primary care setting, which was already found to be valid and reliable in the diagnosis of gastroesophageal reflux disease (GERD). As an English and a German version of the RDQ exist, but not an Italian one, we aimed at translating the RDQ into Italian and evaluating its reliability for the use of Italian-speaking GERD patients. For the purpose of linguistic validation, we translated backward and forward the original RDQ into Italian and again into English. For the purpose of assessing internal consistency, test-retest, and interrater reliability, 130 GERD patients were used, of whom 57 patients had an endoscopic oesophagitis of grade A to C according to the Los Angeles classification and 63 patients had uninvestigated GERD symptoms but with a frequency of heartburn and/or regurgitation at least twice a week. After professional translation, the Italian RDQ was judged to retain fully the meaning of the original RDQ. Internal consistency, as judged by the (Cronbach's alpha) was satisfactory, with an overall RDQ scale alpha=0.86 (minimum acceptable value=0.70). Test--retest reliability (Spearman coefficient) was again found to be optimal, with individual item values ranging between 0.74 (for 'pain in the upper stomach: frequency') and 0.90 (for 'burning feeling behind breastbone: severity'). Finally, the correlation coefficient was 0.96 for the total scale and a range of 0.85-0.98 for individual items, indicating extremely satisfactory concordance. The Italian RDQ appears to be a simple, reproducible, and reliable tool for the diagnosis of GERD. We believe that this questionnaire is well suited for use, both in primary care settings and in epidemiological studies, in particular for the assessment of so-called typical symptoms.

A comparative evaluation of groundwater suitability for irrigation and drinking purposes in two intensively cultivated districts of Punjab, India

Punjab is the most cultivated state in India with highest consumption of fertilizers. Patiala and Muktsar districts are two agricultural dominated districts of Punjab located in extreme south-east and south-west of the state. This paper highlights temporal variations of the groundwater quality and compares its suitability for irrigation and drinking purpose in these two districts. Water samples were collected in March and September 2003 representing the pre-monsoon and post-monsoon seasons respectively. Water samples were analyzed for almost all major cations, anions, dissolved heavy metals and turbidity. Parameters like sodium adsorption ratio, % sodium, residual sodium carbonate, total hardness, potential salinity, Kelley’s ratio, magnesium ratio, Index of Base Exchange and permeability index were calculated on the basis of chemical data. A questionnaire was also used to investigate perception of villagers on taste and odour. Comparison of the concentration of the chemical constituents with WHO (world health organization) drinking water standards of 2004 and various classifications show that present status of groundwater in Patiala is better for irrigation and drinking purposes except for a few locations with a caution that it may deteriorate in near future. In Muktsar, groundwater is not suitable for drinking. Higher total hardness and TDS at numerous places indicate the unsuitability of groundwater for drinking and irrigation. Such areas require alternate drinking water resources identification along with adequate drainage and growing alternate salt tolerance cropping. This groundwater can thus be used after soil treatment or in the soils having sufficient permeability. Results obtained in this forms a baseline data for the utility of groundwater. In terms of monsoon impact, Patiala groundwater shows dilution and flushing but Muktsar samples show excessive leaching of different chemical components into the groundwater leading to enrichment of different anions and cations indicating pollution from extraneous sources. No clear correlation between the quality parameters studied here and perceived quality in terms of satisfactory taste response were obtained at EC values higher than the threshold minimum acceptable value.

Analysis and reporting of platelet kinetic studies

BACKGROUND: For platelet (PLT) kinetic studies in the healthy subject, autologous transfusion models are standardly used for the evaluation of new or modified PLT collection or treatment methods. The investigator is usually seeking to demonstrate that the new product is not inferior to a control condition. Consistent, statistically sound analysis and reporting methods will enable clear interpretation and communication of the results.STUDY DESIGN AND METHODS: Noninferiority hypotheses are constructed in light of a recent FDA workshop. One‐ and two‐stage analysis methods are described to evaluate the paired differences in control and test arms with calculation of upper confidence intervals. Sample size estimates are presented for various experimental design options. The sensitivity of sample size to the difference in test and control recoveries is performed.RESULTS: The noninferiority hypothesis test was applied to a recently published study. Seven‐day, plasma‐stored apheresis PLTs were shown to be noninferior to freshly prepared PLTs with 95 percent confidence that the difference in recovery was not more than 11.4 percent and survival not more than 2.6 days, with maximum acceptable differences of 19.8 percent and 4.4 days. As the test recovery and survival approach the minimum acceptable value, the sample size required to demonstrate noninferiority increases nonlinearly. Preliminary sample size calculations presented here suggest that for most studies such as this, a minimum sample size of 7 should be anticipated. Because most of these studies are used to support regulatory submissions, this is usually executed in at least two centers for a total minimum of 14.CONCLUSION: The randomized, paired design is the most efficient approach to these studies. Consistent reporting of summary statistics for each test arm and the paired differences, the upper confidence limit for the differences in recovery and survival, and the maximum acceptable difference for each is recommended.

Phosphorylation of Ser-129 Is the Dominant Pathological Modification of α-Synuclein in Familial and Sporadic Lewy Body Disease

A comprehensive, unbiased inventory of synuclein forms present in Lewy bodies from patients with dementia with Lewy bodies was carried out using two-dimensional immunoblot analysis, novel sandwich enzyme-linked immunosorbent assays with modification-specific synuclein antibodies, and mass spectroscopy. The predominant modification of alpha-synuclein in Lewy bodies is a single phosphorylation at Ser-129. In addition, there is a set of characteristic modifications that are present to a lesser extent, including ubiquitination at Lys residues 12, 21, and 23 and specific truncations at Asp-115, Asp-119, Asn-122, Tyr-133, and Asp-135. No other modifications are detectable by tandem mass spectrometry mapping, except for a ubiquitous N-terminal acetylation. Small amounts of Ser-129 phosphorylated and Asp-119-truncated alpha-synuclein are present in the soluble fraction of both normal and disease brains, suggesting that these Lewy body-associated forms are produced during normal metabolism of alpha-synuclein. In contrast, ubiquitination is only detected in Lewy bodies and is primarily present on phosphorylated synuclein; it therefore likely occurs after phosphorylated synuclein has deposited into Lewy bodies. This invariant pattern of specific phosphorylation, truncation, and ubiquitination is also present in the detergent-insoluble fraction of brain from patients with familial Parkinson's disease (synuclein A53T mutation) as well as multiple system atrophy, suggesting a common pathogenic pathway for both genetic and sporadic Lewy body diseases. These observations are most consistent with a model in which preferential accumulation of normally produced Ser-129 phosphorylated alpha-synuclein is the key event responsible for the formation of Lewy bodies in various Lewy body diseases.

Evaluation of Multiprotein Immunoaffinity Subtraction for Plasma Proteomics and Candidate Biomarker Discovery Using Mass Spectrometry

Strategies for removal of high abundance proteins have been increasingly utilized in proteomic studies of serum/plasma and other body fluids to enhance the detection of low abundance proteins and achieve broader proteome coverage; however, both the reproducibility and specificity of the high abundance protein depletion process still represent common concerns. Here we report a detailed evaluation of immunoaffinity subtraction performed applying the ProteomeLab IgY-12 system that is commonly used in human serum/plasma proteome characterization in combination with high resolution LC-MS/MS. Plasma samples were repeatedly processed using this approach, and the resulting flow-through fractions and bound fractions were individually analyzed for comparison. The removal of target proteins by the immunoaffinity subtraction system and the overall process was highly reproducible. Non-target proteins, including one spiked protein standard (rabbit glyceraldehyde-3-phosphate dehydrogenase), were also observed to bind to the column at different levels but also in a reproducible manner. The results suggest that multiprotein immunoaffinity subtraction systems can be readily integrated into quantitative strategies to enhance detection of low abundance proteins in biomarker discovery studies.

Prediction of melt geometry in laser cutting

In this paper, an analytical model for the evaluation of the melt film geometry in laser cutting of steels is developed. Using as basis, a previous model for kerf geometry estimation developed by the authors, with both reactive and non-reactive process gases, the film thickness and velocity were determined as a function of the kerf depth in the cutting plate. Two criteria were then adopted to predict the quality of the laser cutting operation: the first is based on a minimum acceptable value of the ejection speed of the melt from the bottom of the kerf, the second on the occlusion of the kerf itself due to an excess of molten material in the boundary layer at the kerf width. These criteria determined a feasibility region in the domain of the process and material variables, such as cutting speed, assistant gas pressure, laser beam power and material characteristics. These factors may be successfully used to build a process-planning tool for parameters optimisation and setting, in order to achieve a satisfactory process quality. The model response is in excellent agreement with the feasibility regions reported from experimental data by various authors and demonstrates a relationship between the occurrence of dross adhesion and the two different mechanisms predicted for such a phenomenon were: unsatisfactory ejection speed of the melt film from the bottom of the kerf and occlusion of the kerf.

Evaluating Process Capability for Geometrically Toleranced Parts: A Practical Approach

The practice of geometric tolerancing has gained in industry popularity since the 1990s. This approach has advantages over conventional tolerancing in defining both geometry and associated tolerance and, thus, generating a more realistic “acceptable design space.” There have been a number of highly mathematical treatments of the subject over the years which have not found their way into popular usage. We look at a specific example of geometric tolerancing and derive a simple approach based on the geometry of the situation and standard C p and C pk calculations. The study describes an approach based on understanding the limiting conditions of acceptable operation. In the example of a pin and clearance hole, we derive the limiting condition as a zero radial gap for a hole and a perfectly centered pin at maximum metal condition. We then performed a standard C pk calculation with the limiting condition acting as the effective tolerance limit. Because we are dealing with radial gaps, we have an effective one-sided tolerance with a minimum acceptable value of 0 for the radial gaps. We tested the approach using Normally distributed simulated data and found that it provides an accurate evaluation of process capability and projected scrap levels. With minor cautions, we conclude that this methodological approach could be extrapolated to other geometrically toleranced situations.

Cost- and Longevity-Based Scheduling of Paint and Thermoplastic Striping

Because no national guidelines exist on establishing pavement marking service life, the scheduling of road striping has been inconsistent among maintenance agencies. This study establishes a way to set striping schedules that accounts for factors affecting scheduling, mainly application cost, service lifetime, and user cost relative to crashes during the striping lifetime. Striping useful lifetime is defined as the striping age beyond which pavement markings become ineffective in relaying necessary vehicle positioning information, when deteriorated pavement marking retroreflectivity reaches a minimum acceptable value. An exponential regression model was used to depict the relationship between striping age and average daily traffic (ADT), using a retroreflectivity threshold of 150 mcd/m2/1x. Striping useful lifetime was established for ADT levels using exponential regression analysis. Application costs were based on the latest available unit costs from the Alabama Department of Transportation for white and yellow longitudinal stripes of paint and thermoplastic markings. Using the National Safety Council estimates of crash severities, user costs were based on the dollar equivalency of the damage to vehicles and occupants in retroreflectivity-related crashes. The data were extracted from the crash experience of approximately 1,300 mi (2100 km) of state highways in 32 Alabama counties. For use in scheduling striping, paint and thermoplastic striping costs were compared on an equivalent annual basis, accounting for application and user costs. Although the crash data and retroreflectivity data were collected on Alabama roads, the findings and conclusions are applicable to areas of warmer climate where snowfall is uncommon.

Multiple attribute evaluation of landscape management

Economic approaches to the valuation of ecological services have several limitations. Some of these limitations can be overcome using the multiple attribute decision-making model developed in this paper. The model postulates that a private or public decision-maker selects a site/landscape management plan based on the biophysical and economic attributes of alternative management plans, the decision-maker’s preferences for attributes, and constraints on the selection of a management plan.Two cases are examined. Case A is a watershed consisting of publicly owned land that is managed at the site, management unit and landscape scales. Management is based on the philosophy of ecosystem management. Case B is a watershed composed of several privately owned units that are managed at the site scale by decision-makers whose primary motivation is economic profit. The preferred management plan in both cases is determined using a two-stage procedure. The first stage uses a stochastic programming model to identify the most efficient management plans for a site/landscape. The second stage determines which efficient management plan for a site/landscape is preferred by maximizing an expected utility function that is additive in the attributes and assumes that the decision-maker is risk neutral.Whether a land-management plan results in strongly or weakly sustainable resource conditions is evaluated. Strong sustainability requires the probability of exceeding the minimum acceptable value of an attribute to be greater than or equal to a pre-determined reliability level for each attribute. Weak sustainability requires the same condition except that it applies to a composite index of the attributes rather than each attribute. Bayes theorem is used to evaluate uncertainty about whether the state of a landscape is sustainable.

A methodology to estimate remaining service life of grey cast iron water mains

The decision to repair, renew, or replace existing old grey cast iron mains is typically based on performance indicators such as structural integrity, hydraulic efficiency, system reliability, and water quality. Structural integrity (often quantified as the number of main breaks per kilometre or mile per year) is the most common performance indicator. However, these indicators represent past performance, rather than expected future performance. Decisions based on performance indicators may not, therefore, accurately meet the real needs of the utility owner of the water distribution system. A preferred approach to make decisions on pipe repair and replacement is to determine the expected remaining service (residual) life of each pipe segment and ensure that the necessary work is performed before failure occurs. Past efforts to estimate remaining service life of water mains have been based on corrosion pit depth and estimated corrosion rate with no regard to the influence of corrosion on the structural resistance capacity of water mains. This paper describes a methodology to estimate the remaining service life of grey cast iron mains that takes corrosion pit induced changes in the structural resistance capacity into account. The methodology combines the residual resistance capacity of grey cast iron mains, anticipated corrosion rates, and the measurement of corrosion pits by direct inspection or non-destructive evaluation technology to predict when the factor of safety of an individual pipe segment will fall below a minimum acceptable value set by the utility owner, i.e., remaining service life. The estimate of remaining service life may then be used to schedule appropriate maintenance or replacement of grey cast iron mains.Key words: water mains, remaining service life, residual life, repair, renew, or rehabilitate water mains, corrosion models, pit and spun grey cast iron.

Bicriteria integer quadratic programming problems

This article presents a solution technique to generate the exhaustive set of efficient solutions of a bicriteria integer quadratic programming problem. An integer quadratic programming problem with one of the objective functions as the principal objective is considered. By varying the minimum acceptable values of the second objective. a sequence of constrained single objective integer quadratic programming problems is solved by ranking the integer feasible solutions of a related integer linear programming problem. These solutions help in generating the complete set of efficient solutions. In ranking the integer feasible solutions we start with an optimal feasible solution of the related integer linear programming problem and we use post-optimality procedures to find the next best integer feasible solutions.

A Close Look at13C CPMAS Linewidths in Solids for Rigid, Strongly Coupled Carbons under CW Proton Decoupling

Ambient-temperature13C linewidth (LW) and transverse relaxation (TC2) data are presented for the natural-abundance crystalline carbons of linear polyethylene (LPE) under CW proton decoupling conditions and magic angle spinning (MAS). This linewidth behavior typifies that seen for rigid methylene carbons whose attached protons are also strongly coupled to other protons. These data are presented for two LPE samples (unoriented, melt-crystallized and uniaxially oriented, extruded) as a function of several parameters including static field (1.4 T <B0< 9.4 T), proton decoupling field strength (38 kHz < νH1< 90 kHz), MAS frequency (0.5 kHz < νr< 8 kHz) and RF frequency offsets from resonance (−4 kHz < Δνoff< 4 kHz). It is the ubiquitous nature of off-resonance proton irradiation (ORPI) (arising from fixed or rotationally dependent deviations from the true proton resonance condition) which provides the focus for this work. Corresponding contributions, LW(ORPI), to the total LW are treated within the general framework of the effective-field picture of CW decoupling. Then, considering the presence of spin fluctuations characteristic of the strongly-dipolar-coupled protons of LPE, LW(ORPI) can be traced to orbit-dependentTC2contributions to LW. Important dependences demonstrated and discussed include: (1) For “off-resonance” decoupling, there is a quadratic dependence of LW(ORPI) on (Δνoff/νH1)andthere is a strong dependence of the corresponding parabolic coefficient on νr. From the latter dependence, characteristic times for spin fluctuations are also estimated. (2) For “on-resonance” decoupling, LW(ORPI) is proportional to (νH1)−2andshows very little sensitivity to νr. These LW(ORPI) contributions become more important at higherB0since the principle reason for ORPI is the chemical shift anisotropy (CSA) of the13C-bonded protons. The difference in sensitivities of LW(ORPI) to νrfor the off-resonance and the on-resonance cases is traced back, respectively, to the scalar property of Δνofffor RF frequency offsets and to the tensorial character of the proton CSA. Contributions from LW(ORPI), possibly much larger than those seen in LPE, can be expected when protons near13C nuclei sense any non-scalar, rotor-position-dependent magnetic fields, e.g., (a) local dipolar fields associated with third, magnetic nuclei or (b) perturbing magnetic-susceptibility fields arising from paramagnetic or ferromagnetic inclusions in a sample. By understanding the contributions to LW in LPE, one can forecast much more precisely what the potential benefits will be from new decoupling schemes like the recently reported “two-pulse phase modulation” (TPPM) since TPPM is designed to reduce LW(ORPI). Aside from LW(ORPI) contributions, the experimental LW data cover parameter space where another broadening mechanism, namely, MAS-assisted dipolar fluctuations (MADF), is seen. This mechanism, also recognized by others, creates aTC2-type linewidth contribution which increases rapidly as νH1decreases and which additionally has some orbit dependence. If the current trend in13CCPMAS is toward higherB0and νr, the νr-dependent MADF contributions can easily dominate LW relative to theB0-dependent LW(ORPI) contributions. One can avoid serious MADF broadening; however, the minimum acceptable values of νH1for good decoupling rise rapidly withB0. Finally, a few LW measurements are made on methyl-α-d-glucopyranoside tetraacetate (MGT), a rigid, polycrystalline material containing carbons with 0, 1, 2, and 3 attached protons. The behaviors of the methylene, methine, and methyl carbons at 9.4 T are compared with the behavior of LPE.

The National Acoustic Laboratories' procedure for selecting the saturation sound pressure level of hearing aids: theoretical derivation.

This paper presents the derivation of a procedure for prescribing the saturation sound pressure level (SSPL) of hearing aids. The procedure is designed to be used with either measured values of loudness discomfort level (LDL) or with hearing threshold values alone. SSPL needs to be low enough to prevent the hearing aid from causing loudness discomfort to the aid wearer but high enough to prevent the hearing aid from being excessively saturated by speech. The maximum SSPL likely to be acceptable can be predicted by measuring LDL or by estimating LDL from hearing thresholds. The minimum SSPL likely to be acceptable can be predicted by calculating, for any particular hearing loss, the amount of gain likely to be needed and hence the SSPL needed if the speech input signal is continuous discourse at an overall level of 75 dB SPL. The midpoint between the minimum and maximum acceptable SSPL values is defined as the optimal or prescribed SSPL, and the three frequency average (3FA; 500, 1000, and 2000 Hz) value of this can be predicted from the 3FA hearing thresholds. Alternatively, the SSPL prescription at each frequency can be prescribed on the basis of the hearing aid gain at each frequency. For either method, the SSPL prescription needs to be increased for people with a conductive component to their hearing losses. The SSPL prescription, when referred to a 2-cc coupler, needs to be decreased for infants, for deeply inserted hearing aids, for multichannel hearing aids that limit SSPL separately in each band, and possibly for nonlinear hearing aids. The 3FA SSPL prescribed for persons with a sensorineural hearing loss increases linearly from 89 dB SPL for normal hearing to 107 dB SPL for a person with a 60 dB HL 3FA loss, and then linearly again to 139 dB SPL for a person with a 120 dB HL 3FA loss. The procedure predicts that the acceptable range of SSPLs is very wide for people with mild losses but is vanishingly small for people with profound losses.

The desired dose distribution in blood irradiators

The irradiation of blood products is indispensable in order to avoid the otherwise associated Graft-Versus-Host-Disease. Normally a dose of 30 Gy is considered to be adequate with a minimum acceptable value of 25 Gy. Approximately 67 blood irradiators are now in operation in Germany. By means of thermoluminescence-dosimeters both dose and dose distribution in the beaker were determined in 15 institutes. Three institutes were found that they did not irradiate the blood bags with the recommended dose of 30 Gy but with 35 Gy or even 40 Gy instead. The extreme percentage dose deviations of the investigated institutes were 83.2% and 156.8% of the nominal value. The minimum percentage dose was as low as 32.1% and as high as 96.6%. On the axis of rotation of the beaker, deviations of up to 57% occurred; an average deviation of 27% being typical. Ten institutes fell short of the minimum accepted dose of 25 Gy whereas only 8 institutes achieved a mean dose in the beaker of 30 Gy or more with a maximum mean value of 38.8 Gy. Therefore regulations regarding quality assurance and dosimetry procedures for blood irradiators appear indispensable.

Focal Species: A Multi‐Species Umbrella for Nature Conservation

To prevent the further loss of species from landscapes used for productive enterprises such as agriculture, forestry, and grazing, it is necessary to determine the composition, quantity, and configuration of landscape elements required to meet the needs of the species present. I present a multi‐species approach for defining the attributes required to meet the needs of the biota in a landscape and the management regimes that should be applied. The approach builds on the concept of umbrella species, whose requirements are believed to encapsulate the needs of other species. It identifies a suite of “focal species,” each of which is used to define different spatial and compositional attributes that must be present in a landscape and their appropriate management regimes. All species considered at risk are grouped according to the processes that threaten their persistence. These threats may include habitat loss, habitat fragmentation, weed invasion, and fire. Within each group, the species most sensitive to the threat is used to define the minimum acceptable level at which that threat can occur. For example, the area requirements of the species most limited by the availability of particular habitats will define the minimum suitable area of those habitat types; the requirements of the most dispersal‐limited species will define the attributes of connecting vegetation; species reliant on critical resources will define essential compositional attributes; and species whose populations are limited by processes such as fire, predation, or weed invasion will define the levels at which these processes must be managed. For each relevant landscape parameter, the species with the most demanding requirements for that parameter is used to define its minimum acceptable value. Because the most demanding species are selected, a landscape designed and managed to meet their needs will encompass the requirements of all other species.

Quality changes in packaged salad products during storage

The quality of four types of packaged salad products (retail and foodservice Garden salad, Caesar salad, and European salad) manufactured by five major processors and stored at 5 °C for 20 days was assessed. The O2 and CO2 concentrations in the bags were 0.2–1.5% and 5–30%, respectively. Overall visual quality scores were generally at or above the minimum acceptable value for salability at the “Best if Used by Date” (12–16 days after processing). Product sensory attributes (visual, flavor and textural properties) determined by a trained judge and a sensory panel significantly correlated for most of the parameters. Off-odors developed in the packages and their scores significantly correlated with ethanol and acetaldehyde concentrations in the lettuce tissue. Sugar content decreased 12% (iceberg) to 20% (romaine) from days 0 to 15. Total aerobic microbial load increased by an average of 2.5–3 log units over 20 days.