Temperature gradients in the microwave-irradiated egg: implications for avian teratogenesis

Five experiments were performed on a total of 60 non-fertile eggs of Gallus gallus to determine the spatial character, persistence, and physical basis of thermal gradients after a 300-s exposure to the intense, multipath, 2.45-GHz yield of a multimode cavity (dose rates: approximately 80 to 120 mW/g). After irradiation of an intact egg that was first equilibrated to the ambient temperature, a 3-mm diameter Plexiglas rod, which was fitted with junctions of four microwire thermocouples at 10-mm intervals, was inserted to place the distal junction in the approximate center of the yolk, the most proximal junction in peripheral thin white. Temperatures measured immediately after irradiation revealed a highly reliable linear gradient of mean temperatures from central yolk to peripheral white (P less than 0.001). The gradient was also highly persistent: Mean temperatures of central yolk exceeded those of outer thin white by more than 4 degrees C 5 minutes after irradiation, and by more than 2 degrees C 60 minutes afterward. In contrast, when an egg's contents were mixed before irradiation, the gradient was effectively eliminated. A previous report of athermally induced (field-specific) teratogenesis in chick embryos is placed under an interpretive cloud by the present findings: Terata emerged from eggs that were structurally intact during microwave irradiation, but estimates of maxima of embryonic temperatures were based on thermal measurements of non-fertile eggs the contents of which had been mixed by a thermal probe before irradiation.     

Construction and decoding of a class of algebraic geometry codes

A class of codes derived from algebraic plane curves is constructed. The concepts and results from algebraic geometry that were used are explained in detail; no further knowledge of algebraic geometry is needed. Parameters, generator and parity-check matrices are given. The main result is a decoding algorithm which turns out to be a generalization of the Peterson algorithm for decoding BCH decoder codes     

Fast decoding of codes from algebraic plane curves

Improvement to an earlier decoding algorithm for codes from algebraic geometry is presented. For codes from an arbitrary regular plane curve the authors correct up to d*/2-m² /8+m/4-9/8 errors, where d* is the designed distance of the code and m is the degree of the curve. The complexity of finding the error locator is O(n^7/3 ), where n is the length of the code. For codes from Hermitian curves the complexity of finding the error values, given the error locator, is O(n²), and the same complexity can be obtained in the general case if only d*/2-m²/2 errors are corrected     

Entropy bounds for constrained two-dimensional random fields

The maximum entropy and thereby the capacity of two-dimensional (2-D) fields given by certain constraints on configurations is considered. Upper and lower bounds are derived. A new class of 2-D processes yielding good lower bounds is introduced. Asymptotically, the process achieves capacity for constraints with limited long-range effects. The processes are general and may also be applied to, e.g., data compression of digital images. Results are given for the binary hard square model, which is a 2-D run-length-limited model and some other 2-D models with simple constraints     

Perinatal intervention trial in Africa: effect of a birth canal cleansing intervention to prevent HIV transmission

BACKGROUND: Perinatal transmission of human immunodeficiency virus (HIV) type 1 contributes significantly to infant mortality. Exposure in the birth canal may account for some transmission. We examined the efficacy of a birth canal washing procedure in reducing perinatal transmission in Malawi. METHODS: The infection status of infants of 3327 control women (conventional delivery procedures) was compared with that of 3637 infants of intervention-delivered women. The infants' HIV status was determined by polymerase chain reaction on dried blood spots collected at 6 and 12 weeks of age. The intervention consisted of manual cleansing of the birth canal with a cotton pad soaked in 0.25% chlorhexidine, which was done on admission in labour and every 4 h until delivery. FINDINGS: No adverse reactions to the intervention procedure were seen. 2094 (30%) of the enrolled women were HIV-infected, and 59% of their infants were seen in follow-up. Among 982 vaginal vertex singleton deliveries to HIV-infected women, 269 (27%) infants were infected. The intervention had no significant impact on HIV transmission rates (27% in 505 intervention women compared with 28% in 477 control women), except when membranes were ruptured more than 4 h before delivery (transmission 25% in the intervention group vs 39% in the control group). INTERPRETATION: If birth canal exposure is an important risk factor, different or additional methods to reduce the risk of perinatal HIV transmission should be tested. Alternatively, perhaps birth canal exposure is not a major contributor to perinatal infection risk.     

A comparative study of DNA extraction methods to be used in real-time PCR based quantification of ochratoxin A-producing molds in food products

Quantification of ochratoxin A (OTA)-producing molds in foods by real-time quantitative PCR (qPCR) may be affected by the DNA extraction method used. In the present work, 6 different methods for extraction of DNA from ochratoxigenic molds in foods were tested. Several combinations of mechanical and thermal lysis of conidia with commercialized DNA extraction kits and enzymatic treatments or resins were evaluated. DNA recovery and quality of extracted DNA was measured by testing the extracted DNA with a conventional PCR and an SYBR Green qPCR amplifying the β-tubulin gene and the non-ribosomal peptide synthetase gene, otanpsPN. Inhibition of conventional and qPCR was not observed when the DNA-extraction method includes an initial thermal disruption of conidia before use of commercialized extraction kit or resin, enzymatic treatment and/or lysis buffer. Of the six methods tested, the one combining thermal lysis of conidia followed by a short enzymatic treatment and incubation with Chelex-100 resin and final extraction with the EZNA kit was selected, since the extracted DNA showed good amplification by conventional PCR for β-tubulin gene and the highest DNA recoveries when tested by qPCR. The method was subsequently validated in different food products such as ripened foods, nuts, and grapes inoculated with Penicillium and Aspergillus species. With this Chelex100-enzymatic-EZNA method good DNA recoveries ranging from 69 to 99% were obtained for all food matrices and fungal species tested. This fast method is a promising tool to be used as routine analysis in HACCP systems in the food industry for quantifying OTA-producing molds by qPCR.     

Fast calculation of impulse responses without multiplications

The impulse response of a linear system may be calculated from the response to a pseudorandom sequence. If the calculation is based on the fast Hadamard transform, only additions and subtractions are required.     

p59OASL, a 2'-5' oligoadenylate synthetase like protein: a novel human gene related to the 2'-5' oligoadenylate synthetase family

The 2'-5' oligoadenylate synthetases form a well conserved family of interferon induced proteins, presumably present throughout the mammalian class. Using the Expressed Sequence Tag databases, we have identified a novel member of this family. This protein, which we named p59 2'-5' oligoadenylate synthetase-like protein (p59OASL), shares a highly conserved N-terminal domain with the known forms of 2'-5' oligoadenylate synthetases, but differs completely in its C-terminal part. The C-terminus of p59OASL is formed of two domains of ubiquitin-like sequences. Here we present the characterisation of a full-length cDNA clone, the genomic sequence and the expression pattern of this gene. We have addressed the evolution of the 2'-5' oligoadenylate synthetase gene family, in the light of both this new member and new 2'-5' oligoadenylate synthetase sequence data from other species, which have recently appeared in the databases.