The use of added error to avoid disclosure in microdata releases

By law, government agencies like the Census Bureau and the National Center for Health Statistics must disseminate collected data in such a way that a respondent cannot be identified. Deleting identifiers (e.g., name, address) from each data record is a standard technique practiced by releasing agencies to preserve the confidentiality of each respondent. Though this inhibits potential intruders from directly identifying a respondent, an additional confidentiality concern stems from the presence of non-confidential public use data files in which direct identifiers have not been removed. If statistical techniques can be used to link a public use data record to a released data record, an intruder may be able to identify a respondent\u27s confidential attributes. One method of preventing disclosure when other files are available to the intruder, is disguising or masking each data vector in the file;In this research, we concentrate on the data perturbation technique of masking each data vector by adding a random error vector. After describing the general procedure, we consider the approach an intruder might use in attempting to determine an individual\u27s confidential attributes. It is shown that the conditional expected value of the attributes given the masked data and the public data is the best predictor of the unknown attributes;We investigate the effect of the covariance structure of the error vectors on the success of the intruder. It is demonstrated that, if the variance of the added error is fixed at a fraction of the variance of the original variables, then the optimal correlation structure of the errors with respect to confidentiality protection is the correlation structure of the original variables;We present a masking algorithm designed to preserve the moments and univariate distribution functions of masked variables, while providing disclosure protection. The degree of protection is a function of the variance of the added error. A computer program that implements the algorithm is outlined. The procedure is designed so that the covariance structure of the masked data is similar to that of the original data. Results of masking example data files with the computer program are summarized

A Fresh Start to Bankruptcy Exemptions

Bankruptcy has broadly failed to deliver “fresh starts” to debtors. Too often, debtors return to states of financial distress following bankruptcy. Although bankruptcy delivers a clean slate through the discharge of debts, the efficacy of a fresh start depends on a second factor: property exemptions. While discharge frees a debtor from her existing debts, property exemptions determine what property the debtor retains upon exiting bankruptcy. For many debtors, insufficient and suboptimal property exemption laws undermine fresh starts. In fact, under current bankruptcy law, each state can reject federal bankruptcy exemptions by opting out. Bankrupt debtors in “opt-out” states are forced to rely on general state exemptions—often stingy and focused on preserving homesteads—that were not designed for bankruptcy. Existing literature explores two lines of criticism against the federal opt-out provision: (1) arguing that the law should be struck down as repugnant to constitutional notions of uniformity, supremacy, or both, and (2) making the case for repeal on normative and fairness grounds. For decades, neither solution has been forthcoming. The opt-out scheme, at first aberrant and controversial, has proved a perdurable feature of bankruptcy law. This Article advances a different approach and proposes diffusive, state-based reform solutions. Under this approach, each opt-out state would undertake a meaningful review of its existing exemptions regime in light of the federally declared rehabilitative function of bankruptcy. I propose a model, to be used in this review, involving three factors— housing agnosticism, nominal sufficiency, and allocative flexibility—as a conceptual framework for reforms. Addressing constitutional concerns, this Article argues that these innovative “bankruptcy-specific exemptions” schemes should survive constitutional scrutiny. The Article ends with discussion of the model and proposed reform framework

Naturally cured meats: Quality, safety, and chemistry

Consumers\u27 concerns about nitrite and nitrate consumption led meat processors to begin manufacturing products without adding sodium nitrite or nitrate. The USDA created special labeling requirements for these products requiring the common name followed by Uncured. The original products within this class were different than traditional cured meats as processors eliminated but did not attempt to replace nitrite. Now, many products within this category utilize a natural nitrate/nitrite source and produce products with traditional cured meat characteristics. In addition, many ingredients commonly added to processed meats to improve product quality and safety are not allowed in products with natural or organic designations. The first study found that these naturally cured products have traditional cured meat characteristics but greater pathogen growth, Clostridium perfringens and Listeria monocytogenes, occurred on many commercial brands of frankfurters, ham, and bacon. Changes in product composition, pH, salt, water activity, and traits related to the curing reaction were correlated to pathogen growth. In the second study, commercially available natural antimicrobials were evaluated for Listeria monocytogenes inhibition in naturally cured ham. Producing naturally cured meats with natural nitrate sources and nitrate reducing starter cultures resulted in greater ingoing nitrite concentrations than when using pre-converted celery powder that already had nitrate reduced to nitrite. Concentration of ingoing nitrite impacted pathogen growth and antimicrobial effectiveness. With greater ingoing nitrite concentrations in the natural nitrate and starter culture system, both clean label antimicrobials effectively inhibitedL. monocytogenes growth over 35 days of storage at 4y C. The antimicrobials had little impact on other product characteristics. For the third study, a simplified model system was developed to simulate and determine the effects of the curing system on nitrite chemistry. Although nitrite is slowly formed by bacterial reduction of naturally cured meats, this model showed the rate of nitrite addition did not affect nitrosation/nitrosylation reactions. As expected, greater amounts of sodium nitrite increased the nitrosation/nitrosylation reactions and confirmed that myoglobin undergoes nitrosylation before cysteine is nitrosated. Increased ingoing nitrite concentrations in combination with natural antimicrobials may allow production of naturally cured meats with quality and safety characteristics comparable to their conventionally cured counterparts

Comparison of Seeding and Sod-Transplant Methods for Restoring Tallgrass Prairie in Southeastern Nebraska.

Data were collected in Fall, 1993 from a 55-year-old re-established grassland to determine the degree of success of seeding and sodding in re-establishing native prairie species. Species Richness of native species was highest in one seeded re-established site (S = 44), but lowest in a second re-established site (S = 23). Species Richness was second highest at the Native site (S = 42). There was a significant difference (P ≤ 0.05) in Species Diversity between the one seeded and the native treatments. The high diversity in re-established treatments is consistent with that expected of the Intermediate-Disturbance-Hypothesis suggesting the seral nature of the re-established sites. Of the 69 species recorded, 13 occurred in all treatment areas: Seven native grasses (Andropogon gerardii, Andropogon scorpaius, Bouteloua curtipendula, Dichanthelium oligosanthes var. scribnerianum, Eragrostis spectabilis, Panicum virgatum, and Sorghastrum nutans), four native forbs (Achillea millefolium, Ambrosia psilostachya, and Rosa arkansana), and two exotic grass species (Bromus drummonii, and Symphoricarpos orbiculatus) and non-woody species, particularly Bromus inermis emphasize the concern for appropriate management to minimize the impact of these species on either re-established or native sites. This study indicates that efforts to re-establish native tallgrass prairie, whether they include seeding or sodding, can be successful for at least some of the dominant species. However, successful re-establishment of uncommon vascular plants cannot be concluded from the results of this study. Thus, preservation of extant grassland ecosystems remains the best means by which to ensure their preservation

A Fresh Start to Bankruptcy Exemptions

Bankruptcy has broadly failed to deliver fresh starts to debtors Too often debtors return to states of financial distress following bankruptcy Although bankruptcy delivers a clean slate through the discharge of debts the efficacy of a fresh start depends on a second factor property exemptions While discharge frees a debtor from her existing debts property exemptions determine what property the debtor retains upon exiting bankruptcy For many debtors insufficient and suboptimal property exemption laws undermine fresh starts In fact under current bankruptcy law each state can reject federal bankruptcy exemptions by opting out Bankrupt debtors in optout states are forced to rely on general state exemptions ”often stingy and focused on preserving homesteads ”that were not designed for bankruptcybrbrExisting literature explores two lines of criticism against the federal optout provision 1 arguing that the law should be struck down as repugnant to constitutional notions of uniformity supremacy or both and 2 making the case for repeal on normative and fairness grounds For decades neither solution has been forthcoming The optout scheme at first aberrant and controversial has proved a perdurable feature of bankruptcy lawbrbrThis Article advances a different approach and proposes diffusive statebased reform solutions Under this approach each optout state would undertake a meaningful review of its existing exemptions regime in light of the federallydeclared rehabilitative function of bankruptcy I propose a model to be used in this review involving three factors ”nominal sufficiency housing agnosticism and allocative flexibility as a conceptual framework for reforms Addressing constitutional concerns this Article argues that these innovative bankruptcyspecific exemptions schemes should survive constitutional scrutiny The Article ends with discussion of the model and proposed reform frameworkb

Centromere identity in Drosophila is not determined in vivo by replication timing

Centromeric chromatin is uniquely marked by the centromere-specific histone CENP-A. For assembly of CENP-A into nucleosomes to occur without competition from H3 deposition, it was proposed that centromeres are among the first or last sequences to be replicated. In this study, centromere replication in Drosophila was studied in cell lines and in larval tissues that contain minichromosomes that have structurally defined centromeres. Two different nucleotide incorporation methods were used to evaluate replication timing of chromatin containing CID, a Drosophila homologue of CENP-A. Centromeres in Drosophila cell lines were replicated throughout S phase but primarily in mid S phase. However, endogenous centromeres and X-derived minichromosome centromeres in vivo were replicated asynchronously in mid to late S phase. Minichromosomes with structurally intact centromeres were replicated in late S phase, and those in which centric and surrounding heterochromatin were partially or fully deleted were replicated earlier in mid S phase. We provide the first in vivo evidence that centromeric chromatin is replicated at different times in S phase. These studies indicate that incorporation of CID/CENP-A into newly duplicated centromeres is independent of replication timing and argue against determination of centromere identity by temporal sequestration of centromeric chromatin replication relative to bulk genomic chromatin

Properties of Natural and Organic \u27Naturally Cured\u27 Meats

A somewhat unusual aspect to cured natural and organic processed meats is that nitrate and nitrite cannot be added as ingredients, because preservatives are not permitted in natural and organic foods. This has resulted in alternative meat-curing processes that utilize natural sources of nitrate, typically celery juice concentrate or powder