387 research outputs found
Produce handling and processing practices.
In the past decade, outbreaks of human illness associated with the consumption of raw vegetables and fruits (or unpasteurized products produced from them) have increased in the United States. Changes in agronomic, harvesting, distribution, processing, and consumption patterns and practices have undoubtedly contributed to this increase. Pathogens such as Listeria monocytogenes, Clostridium botulinum, and Bacillus cereus are naturally present in some soil, and their presence on fresh produce is not rare. Salmonella, Escherichia coli O157:H7, Campylobacter jejuni, Vibrio cholerae, parasites, and viruses are more likely to contaminate fresh produce through vehicles such as raw or improperly composted manure, irrigation water containing untreated sewage, or contaminated wash water. Contact with mammals, reptiles, fowl, insects, and unpasteurized products of animal origin offers another avenue through which pathogens can access produce. Surfaces, including human hands, which come in contact with whole or cut produce represent potential points of contamination throughout the total system of growing, harvesting, packing, processing, shipping, and preparing produce for consumption. Treatment of produce with chlorinated water reduces populations of pathogenic and other microorganisms on fresh produce but cannot eliminate them. Reduction of risk for human illness associated with raw produce can be better achieved through controlling points of potential contamination in the field; during harvesting; during processing or distribution; or in retail markets, food-service facilities, or the home
Infections associated with eating seed sprouts: an international concern.
Recent outbreaks of Salmonella and Escherichia coli O157:H7 infections associated with raw seed sprouts have occurred in several countries. Subjective evaluations indicate that pathogens can exceed 107 per gram of sprouts produced from inoculated seeds during sprout production without adversely affecting appearance. Treating seeds and sprouts with chlorinated water or other disinfectants fails to eliminate the pathogens. A comprehensive approach based on good manufacturing practices and principles of hazard analysis and critical control points can reduce the risk of sprout-associated disease. Until effective measures to prevent sprout-associated illness are identified, persons who wish to reduce their risk of foodborne illness from raw sprouts are advised not to eat them; in particular, persons at high risk for severe complications of infections with Salmonella or E. coli O157:H7, such as the elderly, children, and those with compromised immune systems, should not eat raw sprouts
Alfalfa Seed Decontamination in Salmonella Outbreak
Based on in vitro data, the U.S. Food and Drug Administration recommends chemical disinfection of raw sprout seeds to reduce enteric pathogens contaminating the seed coats. However, little is known about the effectiveness of decontamination at preventing human disease. In 1999, an outbreak of Salmonella enterica serotype Mbandaka occurred in Oregon, Washington, Idaho, and California. Based on epidemiologic and pulsed-field gel electrophoresis evidence from 87 confirmed cases, the outbreak was linked to contaminated alfalfa seeds grown in California’s Imperial Valley. Trace-back and trace-forward investigations identified a single lot of seeds used by five sprout growers during the outbreak period. Cases of salmonellosis were linked with two sprout growers who had not employed chemical disinfection; no cases were linked to three sprout growers who used disinfection. This natural experiment provides empiric evidence that chemical disinfection can reduce the human risk for disease posed by contaminated seed sprouts
Risky Traitor Tracing and New Differential Privacy Negative Results
In this work we seek to construct collusion-resistant traitor tracing systems with small ciphertexts
from standard assumptions that also move toward practical efficiency. In our approach we will hold
steadfast to the principle of collusion resistance, but relax the requirement on catching a traitor from
a successful decoding algorithm. We define a -risky traitor tracing system as one where the probability of identifying
a traitor is times the probability a successful box is produced. We then go on to show
how to build such systems from prime order bilinear groups with assumptions close to those used in prior works.
Our core system achieves, for any , where ciphertexts consists of group elements
and decryption requires pairing operations.
At first glance the utility of such a system might seem questionable since the we achieve for short ciphertexts
is relatively small. Indeed an attacker in such a system can more likely than not get away with producing a decoding box.
However, we believe this approach to be viable for four reasons:
1. A risky traitor tracing system will provide deterrence against risk averse attackers. In some settings the
consequences of being caught might bear a high cost and an attacker will have to weigh his utility of producing a
decryption box against the expected cost of being caught.
2. Consider a broadcast system where we want to support low overhead broadcast encrypted communications, but
will periodically allow for a more expensive key refresh operation. We refer to an adversary produced algorithm that
maintains the ability to decrypt across key refreshes as a persistent decoder. We show how if we employ a risky traitor
tracing systems in this setting, even for a small , we can amplify the chances of catching such a ``persistent decoder\u27\u27 to
be negligibly close to 1.
3. In certain resource constrained settings risky traitor tracing provides a best tracing effort where
there are no other collusion-resistant alternatives. For instance, suppose we had to support 100K users
over a radio link that had just 10KB of additional resources for extra ciphertext overhead. None of the
existing bilinear map systems can fit in these constraints. On the other
hand a risky traitor tracing system provides a spectrum of tracing probability versus overhead tradeoffs and can
be configured to at least give some deterrence in this setting.
4. Finally, we can capture impossibility results for differential privacy from -risky traitor tracing. Since our
ciphertexts are short (), we get the negative result which matches what one would get plugging
in the obfuscation based tracing system Boneh-Zhandry (CRYPTO 2014) solution into the prior impossibility result
of Dwork et al. (STOC 2009)
Solving a 676-Bit Discrete Logarithm Problem in GF(36n )
Pairings on elliptic curves over finite fields are crucial for constructing various cryptographic schemes. The \eta_T pairing on supersingular curves over GF(3^n) is particularly popular since it is efficiently implementable. Taking into account the Menezes-Okamoto-Vanstone (MOV) attack, the discrete logarithm problem (DLP) in GF(3^{6n}) becomes a concern for the security of cryptosystems using \eta_T pairings in this case. In 2006, Joux and Lercier proposed a new variant of the function field sieve in the medium prime case, named JL06-FFS. We have, however, not yet found any practical implementations on JL06-FFS over GF(3^{6n}). Therefore, we first fulfilled such an implementation and we successfully set a new record for solving the DLP in GF(3^{6n}), the DLP in GF(3^{6 \cdot 71}) of 676-bit size. In addition, we also compared JL06-FFS and an earlier version, named JL02-FFS, with practical experiments. Our results confirm that the former is several times faster than the latter under certain conditions
Polygala extraaxillaris: oxidative stress in Brachiaria decumbens mediated by volatile oils
National Outbreak of Salmonella Serotype Saintpaul Infections: Importance of Texas Restaurant Investigations in Implicating Jalapeño Peppers
BACKGROUND: In May 2008, PulseNet detected a multistate outbreak of Salmonella enterica serotype Saintpaul infections. Initial investigations identified an epidemiologic association between illness and consumption of raw tomatoes, yet cases continued. In mid-June, we investigated two clusters of outbreak strain infections in Texas among patrons of Restaurant A and two establishments of Restaurant Chain B to determine the outbreak's source. METHODOLOGY/PRINCIPAL FINDINGS: We conducted independent case-control studies of Restaurant A and B patrons. Patients were matched to well controls by meal date. We conducted restaurant environmental investigations and traced the origin of implicated products. Forty-seven case-patients and 40 controls were enrolled in the Restaurant A study. Thirty case-patients and 31 controls were enrolled in the Restaurant Chain B study. In both studies, illness was independently associated with only one menu item, fresh salsa (Restaurant A: matched odds ratio [mOR], 37; 95% confidence interval [CI], 7.2-386; Restaurant B: mOR, 13; 95% CI 1.3-infinity). The only ingredient in common between the two salsas was raw jalapeño peppers. Cultures of jalapeño peppers collected from an importer that supplied Restaurant Chain B and serrano peppers and irrigation water from a Mexican farm that supplied that importer with jalapeño and serrano peppers grew the outbreak strain. CONCLUSIONS/SIGNIFICANCE: Jalapeño peppers, contaminated before arrival at the restaurants and served in uncooked fresh salsas, were the source of these infections. Our investigations, critical in understanding the broader multistate outbreak, exemplify an effective approach to investigating large foodborne outbreaks. Additional measures are needed to reduce produce contamination
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