A low-noise differential microphone inspired by the ears of the parasitoid fly Ormia ochracea

A miniature differential microphone is described having a low-noise floor. The sensitivity of a differential microphone suffers as the distance between the two pressure sensing locations decreases, resulting in an increase in the input sound pressure-referred noise floor. In the microphone described here, both the diaphragm thermal noise and the electronic noise are minimized by a combination of novel diaphragm design and the use of low-noise optical sensing that has been integrated into the microphone package. The differential microphone diaphragm measures 1 x 2 mm(2) and is fabricated out of polycrystalline silicon. The diaphragm design is based on the coupled directionally sensitive ears of the fly Ormia ochracea. The sound pressure input-referred noise floor of this miniature differential microphone has been measured to be less than 36 dBA.

First Report of a Pestalotiopsis sp. Causing Leaf Spot of Blueberry in China

In August 2006, leaf spots were observed on half-high blueberry (Vaccinium corymbosum) in a plant nursery in Dalian, China. The symptomatic potted 1-year-old blueberry plants were located in parts of a plant nursery with poor ventilation. The primary symptom was a leaf spot, 0.4 to 0.8 cm in diameter, with brown margins that enlarged and coalesced. Mycelium grew from symptomatic and green leaf tissue removed from the margin of a necrotic leaf spot. Plant tissues were surface disinfested with 0.1% mercuric chloride for 3 min and 70% ethyl alcohol for 30 s before plating onto potato dextrose agar. The resulting colonies were white with a regular margin and a rough surface. The cultures were covered with black and globular acervuli with a diameter of 100 to 200 μm. The base of each conidiophore was swollen and globose with phialides growing from the apical end. Mature conidia were straight to fusiform, measuring 19.0 to 27.5 × 6.3 to 9.2 μm, and five-celled with the three middle cells brown and darker than the end cells. The apical cell was triangular and hyaline with three simple setulae that were 17.2 to 29.7 μm long. The base cell terminated in a point 4.0 to 8.6 μm long. Koch's postulates were fulfilled for the fungus by spray inoculating two healthy young plants with 2 × 10⁵ conidia per ml of sterile distilled water. As a control, two similar plants were sprayed with sterile water. Plants were placed inside plastic bags to maintain humidity and incubated in a growth chamber at 26°C under fluorescent light for 14 h and at 20°C in darkness for 10 h. After 3 days, the plastic bags were removed and plants were maintained under the same conditions. More than 20 days after inoculation, symptoms on inoculated plants were similar to those previously described in the nursery. Control plants did not show any symptoms. Cultures isolated from the lesions were similar to those isolated previously from plants in the nursery. The morphological descriptions and measurements were similar to Pestalotiopsis clavispora (1). The 5.8S subunit and flanking internal transcribed spacers (ITS1 and ITS2) of rDNA and partial β-tubulin gene were amplified from DNA extracted from single-spore cultures using the ITS1/ITS4 and T1/Bt2b primers (2) respectively, and sequenced (GenBank Accession Nos. EF119336 and EF152585). The ITS sequences were most similar to the ITS regions of P. clavispora TA-8 (98%; GenBank Accession No. AY924264), P. clavispora TA-6 (98%; GenBank Accession No. AY924263), and P. clavispora PSHI 2002 Endo 389 (96%; GenBank Accession No. AY682929). The partial β-tubulin gene sequence was identical to Pestalotiopsis sp. isolate PSHI 2004 Endo 86 (100%; GenBank Accession No. DQ657901). The morphology and sequence data support the identity of the causal fungus as P. clavispora. To our knowledge, this is the first report on the presence of a Pestalotiopsis sp. causing a disease of blueberry in China. References: (1) E. F. Guba. Monograph of Monochaetia and Pestalotia. Harvard University Press, Cambridge, MA, 1961. (2) W. Tao et al. Mol. Cell Biol. 27:689, 2007.

Light scattering regimes along the optical axis in turbid media

We inject an angularly collimated laser beam into a scattering medium of a nondairy creamer-water solution and examine the distribution of the scattered light along the optical axis as a function of the source-detector spacing. The experimental and simulated data obtained from a Monte Carlo simulation suggest four regimes characterizing the transition from unscattered to diffusive light. We compare the data also with theoretical predictions based on a first-order scattering theory for regions close to the source, and with diffusionlike theories for larger source-detector spacings. We demonstrate the impact of the measurement process and the effect of the unavoidable absorption of photons by the detection fiber on the light distribution inside the medium. We show that the range of validity of these theories can depend on the experimental parameters such as the diameter and acceptance angle of the detection fiber.

Nonperturbative retrieval of the scattering strength in one-dimensional media

We examine several approaches on how to use the transmission and reflection amplitudes as functions of the modulation frequency of the laser's intensity to reconstruct the position-dependent scattering coefficient for a simple turbid medium. We explore the region where the contrast between the coefficient and its spatially averaged value is large enough such that perturbative methods fail. We show that in the case of a transillumination geometry, the knowledge of the transmission profile alone is not sufficient for unique image reconstruction, whereas the reflection spectrum allows for a complete inversion. We demonstrate the invertibility for media sampled at only a few positions.

Velocity half-sphere model for multiple light scattering in turbid media

We extend the traditional diffusion theory by distinguishing between the energy radiance in the forward and backward directions at each point in space. This approach leads to a new effective source for the diffusion equation that is nonzero for an anisotropic light source. It differs significantly from the diffusion theory for short source-detector spacings. We derive an analytical solution for the two lowest-order velocity moments of the radiance.

Creation dynamics of bound States in supercritical fields

Using space-time resolved solutions to relativistic quantum field theory, we analyze the electron-positron creation process from vacuum in the long-time regime in which multiple pairs are produced. We find that for a supercritical potential of finite extension, the time dependence of the production rate of pairs is described by four distinct regimes that have their direct counterparts in the time evolved spatial density of the particles. These regimes include the shape-invariant birth process, an entanglement-induced reduction of interference, a recurrent Pauli suppression of pair production induced by electron-potential scattering, and finally a production halt associated with a population of supercritical and a partial population of subcritical bound states.

Generalized diffusion solution for light scattering from anisotropic sources

The traditional diffusion theory, often used for isotropic sources, becomes inaccurate at short source-detector spacings and cannot be applied to media with large absorption or with small scattering strengths. We show that for any type of source anisotropy, a Green's-function-based procedure can remove these limitations. The accuracy of the new approach is examined through a comparison with the numerical solution to the radiative transfer equation.

Determination of g and mu using multiply scattered light in turbid media

We propose an inversion scheme to reconstruct the scattering coefficient mu and the anisotropy factor g that characterize the optical properties of a turbid medium. It is based on a theory for the scattering of light inside the medium from an angularly collimated light source. We demonstrate the feasibility of this method using light scattering data obtained from a Monte Carlo simulation.

Comparative study of influenza virus replication in Vero and MDCK cell lines

The choice of a cell line for the production of influenza vaccines is determined by how well the virus is able to replicate and how easily the cell line can be maintained. Madin-Darby canine kidney (MDCK) cells have long been known to successfully support influenza growth. Vero cells are also another well studied candidate cell line. In this work, we have compared these two cell lines for their ability to propagate type A and type B cold-adapted and wild type influenza viruses. The growth of these viruses has been measured as plaque forming units (via plaque assay) as well as viral particle formation (via a novel quantitative RT-PCR assay) to assess the suitability of these cell lines to support the development of live attenuated influenza vaccines. The novel qRT-PCR assay outlined in this work was demonstrated to be an efficient, sensitive and reproducible method for measuring wild type (wt) and cold-adapted (ca) influenza strains. Replicates of six per sample consistently showed an average variation around +/-10%. In this study we have also found qRT-PCR to be a useful method for differentiating between wt and ca influenza strains based on their differing growth characteristics at varying temperatures. This can subsequently be used to assess reassortants prepared from ca donor strains for the purposes of live viral vaccine development. For type A and B influenza viruses studied in this work, MDCK cells supported a more rapid viral growth (measured in terms of genome copies) compared with Vero cells. For the type A viruses studied here, the genome copies: infectious unit (genome copy, gc:infectious unit, iu) ratio was found to be more favorable for Vero cells compared with MDCK cells. For the type B viruses studied in this work, the gc:iu was equivalent in both cell lines tested. Ultimately, however, the use of any new cell line would need to be approved by regulatory agencies prior to its commercial application.

Serum lysophosphatidic acid concentrations measured by dot immunogold filtration assay in patients with acute myocardial infarction

In this study the relation between lysophosphatidic acid (LPA) and myocardial infarction was investigated, the typical and simplified methods for measuring serum LPA concentration by dot immunogold filtration assay (DIFA) based on a polyclonal antibody to LPA were developed, and serum LPA concentrations were measured in 31 patients with acute myocardial infarction (AMI) and 12 controls (blood donors) by DIFA. Serum LPA levels were raised more than twofold 8 h after the onset of AMI. Maximal elevation (10.43 mg/L) was found at 48-72 h following onset and remained higher than the control concentration (1.66 mg/L) 7 days after AMI. The rise in serum LPA concentration in AMI patients suggests that LPA might be involved in AMI-related pathophysiology in the cardiovascular system. The simplified DIFA developed in the present study for measuring serum LPA concentration is convenient and highly sensitive.

Relativistic electron localization and the lack of Zitterbewegung

Using space-time resolved solutions to relativistic quantum field theory we analyze the electron-positron pair creation process from vacuum. For early times the entangled electron-positron wave function can be obtained analytically. We show that there are, in principle, no limitations to the localization length of an electron and demonstrate that its spatial probability density can be much narrower than the Compton wavelength. We also find that quantum field theory prohibits the occurrence of Zitterbewegung for an electron.

Phenotypic and genetic analyses of the heterogeneous population present in the cold-adapted master donor strain: A/Leningrad/134/17/57 (H2N2)

For the past three decades the cold-adapted (ca) and temperature sensitive (ts) master donor strain, A/Leningrad/134/17/57 (H2N2) has been successfully used as the basis for the live attenuated reassortant influenza A vaccine. This donor strain was developed from A/Leningrad/134/57 (H2N2) wild-type (wt) virus following 17 passages in eggs at 25 degrees C. Our detailed investigation has revealed that the A/Leningrad/134/17/57 (Len/17) master donor stock is a mixed population comprised of numerous variants of the ca/ts Len/17 influenza virus. We have identified these variants to exhibit a broad range in their temperature sensitive phenotype when assayed on Madin-Darby canine kidney (MDCK) cells at 37 degrees C. A selection of these variant clones has been fully characterized by sequencing in order to understand the variability in the ts phenotype. This study has also addressed the feasibility of using cell culture technology for the propagation and subsequent manufacturing of the cold-adapted influenza vaccine (CAIV), particularly with respect to retaining the defined mutations that contribute toward the ca/ts phenotype.

Cell-based assay for the determination of temperature sensitive and cold adapted phenotypes of influenza viruses

The determination of temperature sensitive (ts) and cold adapted (ca) phenotype for influenza A and B strains has been conducted traditionally using embryonated chicken eggs. As attempts are made to move away from the use of eggs in the manufacturing process of influenza vaccines, it will become useful to develop cell-based assays to support cell culture-based vaccine production. In this study, MDCK cells have been evaluated as a tool for determining the ts and ca phenotypes associated with live attenuated influenza viruses. Direct comparisons were made of these phenotypes carried out in eggs. Reassortants made from the Russian live attenuated influenza donor strains A/Leningrad/134/17/57 (H2N2) and B/USSR/60/69 were prepared entirely in MDCK cells and their phenotypes evaluated using the MDCK cell-based assay. It is concluded that MDCK cells are more sensitive than eggs for the measurement of ts and ca phenotype of influenza viruses (particularly for influenza A) and they provide an alternative means for screening candidate reassortants prior to determining their genome composition.

Imaging in turbid media using modulation frequency scanning

We propose an imaging scheme to detect an object inside a turbid medium using intensity modulated waves as a probe. We show how the new degree of freedom represented by the modulation frequency allows sufficient control to reconstruct the image from the scattered wave signal.

Klein paradox in spatial and temporal resolution

Based on spatially and temporally resolved numerical solutions to the relativistic quantum field equations, we provide a resolution to the controversial issue of how an incoming electron scatters off a supercritical potential step and how the electron-positron pair production is affected by this collision. The treatment of the problem as a correlated three-particle problem suggests revealing insight into the process.

Extensive sharing of chloroplast haplotypes among European birches indicates hybridization among Betula pendula, B. pubescens and B. nana

Extensive sharing of chloroplast haplotypes among the silver birch, Betula pendula Roth., the downy birch, B. pubescens Ehrh., and the dwarf birch, B. nana L., was discovered using polymerase chain reaction-restriction fragment length polymporphism markers. The geographical component of the genetic variation was stronger than the species component: the species were not significantly different while 11% of the variation could be attributed to differentiation between the two main regions studied, Scandinavia and western Russia. All haplotypes occurring in more than 2% of the individuals were shared among the species and the introgression ratios were quite large: 0.79 between B. pubescens and B. pendula and 0.67 between B. pubescens and B. nana. The data also indicate that B. pendula individuals are more similar to sympatric B. pubescens than to B. pendula individuals from nearby forests. However, this trend is not as pronounced when B. pubescens is considered, suggesting that introgression is not symmetrical. The haplotype sharing among the three Betula species is most likely caused by hybridization and subsequent cytoplasmic introgression.

Bridging the microscopic and macroscopic theories for light reflected from disordered plane-parallel dielectric slabs

For a system of randomly arranged plane-parallel dielectric layers with randomly varying index of refraction and width, we compare the reflection coefficient derived from the Maxwell equations with that of the Boltzmann theory. For a strictly monochromatic field this coefficient is an oscillatory function of the laser frequency. We show how suitable frequency or ensemble averaging permits a comparison of the two theories. The calculation of the usual Boltzmann scattering coefficient from microscopic parameters can be improved to permit a better agreement with the exact Maxwell data.

Role of amination of a polymeric adsorbent on phenol adsorption from aqueous solution

Adsorption of seven phenols, one aromatic carboxylic acid and one sulfonated aromatic acid from aqueous solution, by a hypercrosslinked polymeric adsorbent (CHA-111) and the derivative animated by dimethylamine was compared. The results of different adsorption isotherms indicated that amino group on the polymeric matrix played a significant role on adsorption of almost all the employed compounds. For most employed compounds adsorption capacities increase to different degree and significantly for those with lower value of pK(a). It may be attributed to the enhanced adsorbent-adsorbate interaction for amino group introduced on the polymeric matrix. The empirical Freundlich isotherm equation was employed to interpret the adsorbent-adsorbate interaction. The adsorption enthalpy change indicated the uptake of phenols on MCH-111 to be an enhanced physical adsorption because of the hydrogen-bonding interaction. Adsorption kinetic study of phenols on CHA-111 and MCH-111 was also conducted and amino group on the matrix will reduce the adsorption rate for change of pore size distribution and loss of macroprous volume as well as the hydration effect on the surface partly.

[Experimental therapy of Pagumogonimus skrjabini infection in rats with triclabendazole]

AIM

To observe the therapeutic effect of triclabendazole in rats infected with Pagumogonimus skrjabini.

METHODS

Metacercariae of P. skrjabini were isolated from crabs (Sinopotamon) collected from two endemic areas (Weiyuan County of Sichuan Province and Wansheng District of Chongqing Municipality). Wistar rats were each infected intraperitoneally with metacercariae. One month and two months after infection, the infected rats were treated with triclabendazole at the total dosage of 300 mg/kg over 2 days, 450 mg/kg over 3 days and 600 mg/kg over 3 days, respectively.

RESULTS

The worm reduction rates were 50%, 80% and 87% respectively one month after completion of tretment. Dead worms (about 1 mm size) recovered from the muscles, liver, abdominal cavity, chest cavity and lungs were signicantly diminished in size and weight in comparison with those of the control group. Many large (about 1 cm) black-colored distended worm cysts usually with two adult worms and many eggs were found in the lungs of the control rats. Most worm cysts in the treated groups of rats were found to be atrophied, changing into hemorrhagic-necrotic patches.

CONCLUSION

Triclabendazole is highly active against P. skrjabini in rats.