779 research outputs found
Anisotropic focusing characteristics of micro-domain structures within crystalline Sr<sub>0.61</sub>Ba<sub>0.39</sub>Nb<sub>2</sub>O<sub>6</sub> : the crystal ball
We report the anisotropic focusing characteristics of a spherically configured region of micro-domains that have been induced within a cubic shaped crystal of Ce:doped Sr0.61Ba0.39Nb2O6. The internal spherical structure focuses extraordinary polarised light, but not ordinary polarised. The spherical region, which is easily observed via scattering, is formed as the crystal cools down, after a repoling cycle through the Curie temperature, with an applied field. Analytic modelling of the thermal gradients that exist within the crystal during cooling reveals a small (< 1°) temperature difference between the central and outside regions. The similarity in shape between these temperature profiles and the observed scattering region suggests a possible mechanism for the growth of this spherical micro-domained structure
A posteriori teleportation
The article by Bouwmeester et al. on experimental quantum teleportation
constitutes an important advance in the burgeoning field of quantum
information. The experiment was motivated by the proposal of Bennett et al. in
which an unknown quantum state is `teleported' by Alice to Bob. As illustrated
in Fig. 1, in the implementation of this procedure, by Bouwmeester et al., an
input quantum state is `disembodied' into quantum and classical components, as
in the original protocol. However, in contrast to the original scheme,
Bouwmeester et al.'s procedure necessarily destroys the state at Bob's
receiving terminal, so a `teleported' state can never emerge as a freely
propagating state for subsequent examination or exploitation. In fact,
teleportation is achieved only as a postdiction.Comment: 1 page LaTeX including 1 figure. Scientific Correspondence about:
"Experimental quantum teleportation" Nature 390, 575 (1997
Menstrual management in communal sanitation facilities: recommendations to eThekwini municipality
A growing body of research has shown that menstrual hygiene products (MHPs) are critical to gender equity, and South Africa has committed to providing free sanitary napkins to all indigent women. To address interim water and sanitation needs of its citizens living in informal settlements, South Africaâs eThekwini Water and Sanitation Unit (EWS) constructed community ablution blocks (CABs) that consist of gender-separated toilets, showers, and washbasins. The interactions between women, unfamiliar sanitation systems, and MHPs are likely to impact women and the sanitation systems they utilize. A larger case study led by PATH is evaluating these interactions, within which this sub-study aims to characterize the relationship between CABs and menstrual hygiene management in Durbanâs informal settlements. Based on analysis of information gathered through interviews, photo documentation, and observations, we provide recommendations to EWS that we believe will improve womenâs experiences at CABs and reduce negative impacts on the sanitation systems
Spectral Analysis of Guanine and Cytosine Fluctuations of Mouse Genomic DNA
We study global fluctuations of the guanine and cytosine base content (GC%)
in mouse genomic DNA using spectral analyses. Power spectra S(f) of GC%
fluctuations in all nineteen autosomal and two sex chromosomes are observed to
have the universal functional form S(f) \sim 1/f^alpha (alpha \approx 1) over
several orders of magnitude in the frequency range 10^-7< f < 10^-5 cycle/base,
corresponding to long-ranging GC% correlations at distances between 100 kb and
10 Mb. S(f) for higher frequencies (f > 10^-5 cycle/base) shows a flattened
power-law function with alpha < 1 across all twenty-one chromosomes. The
substitution of about 38% interspersed repeats does not affect the functional
form of S(f), indicating that these are not predominantly responsible for the
long-ranged multi-scale GC% fluctuations in mammalian genomes. Several
biological implications of the large-scale GC% fluctuation are discussed,
including neutral evolutionary history by DNA duplication, chromosomal bands,
spatial distribution of transcription units (genes), replication timing, and
recombination hot spots.Comment: 15 pages (figures included), 2 figure
Mechanism of Oral Tolerance Induction to Therapeutic Proteins
Oral tolerance is defined as the specific suppression of humoral and / or cellular immune responses to an antigen by administration of the same antigen through the oral route. Due to its absence of toxicity, easy administration, and antigen specificity, oral tolerance is a very attractive approach to prevent unwanted immune responses that cause a variety of diseases or that complicate treatment of a disease. Many researchers have induced oral tolerance to efficiently treat autoimmune and inflammatory diseases in different animal models. However, clinical trials yielded limited success. Thus, understanding the mechanisms of oral tolerance induction to therapeutic proteins is critical for paving the way for clinical development of oral tolerance protocols. This review will summarize progress on understanding the major underlying tolerance mechanisms and contributors, including antigen presenting cells, regulatory T cells, cytokines, and signaling pathways. Potential applications, examples for therapeutic proteins and disease targets, and recent developments in delivery methods are discussed
Applicability and accuracy of an intraoral scanner for scanning multiple implants in edentulous mandibles:A pilot study
Statement of problem. In the past 5 years, the use of intraoral digitizers has increased. However, data are lacking on the accuracy of scanning implant restorative platforms for prosthodontics with intraoral digitizers. Purpose. The purpose of this clinical pilot study was to assess the applicability and accuracy of intraoral scans by using abutments designed for scanning (scan abutments) in edentulous mandibles. Material and methods. Twenty-five participants with complete mandibular overdentures retained by 2 implants and frameworks were included in this study. Scan abutments were placed on the implants intraorally and scanned with the iTero intraoral scanner. Also, scan abutments were placed on the implant analogs of the definitive casts and scanned with an extraoral laboratory scanner (Lava Scan ST scanner). Two 3-dimensional computer-aided design models of the scan abutments with predetermined center lines were subsequently imported and registered, together with each of the scanned equivalents. The distance between the centers of the top of the scan abutments and the angulations between the scan abutments was assessed. These values were compared with the measurements made on the 3-dimensional scans ofthe definitive casts, which were the participants' original definitive casts used for fabrication of soldered bars. The threshold for distance error was established to be 100 mu m. Results. Four of the 25 intraoral scans were not suitable for research because the intraoral scanner was not able to stitch the separate scans together. Five of the 21 suitable scans demonstrated an interimplant distance error >100 Rm. Three of the 25 intraoral scans showed interimplant angulation errors >0.4 degrees. Only 1 scan showed both an acceptable interimplant distance ( Conclusions. Based on the intraoral scans obtained in this study, distance and angulation errors were too large to fabricate well-fitting frameworks on implants in edentulous mandibles. The main reason for the unreliable scans seemed to be the lack of anatomic landmarks for scanning
Catalytic combustion of methane on Co/MgO: characterisation of active cobalt sites
A series of Co/MgO catalysts with 3â12 wt.% Co were prepared by impregnation and calcined at 1073 K for 10 h. The catalytic behaviour of these samples toward CH4 combustion was found to increase with cobalt loading, though a plateau was reached at ca. 9 wt.% Co content. Bulk characterisation was carried out using XRD, TPR and Raman spectroscopy, and showed that the solids were made up of a CoOâMgO solid solution and a MgO phase. A detailed examination of their surfaces was achieved through FTIR spectroscopy of adsorbed CO probe molecules, which indicated that at low cobalt loadings only a small proportion of the Co going into the solid solution was present on exposed faces as either Co2+ oxo-species or pentacoordinated Co2+. However, as the cobalt content of the samples increased, a larger amount was exposed on the surface. This effect levelled off at 9 wt.% Co, after which the increase in exposed Co2+ sites was countered by the masking effect of islands of MgO. In addition, at high cobalt loadings (9 and 12 wt.%) Co formed small clusters which showed bulk CoO-like behaviour. Consequently, the benefit of having surface Co2+ species was balanced by the clustering effect of these species and the presence of MgO islands, negating their contribution to the overall catalytic activity of the samples.Fil: Ulla, Maria Alicia del H.. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Santa Fe. Instituto de Investigaciones en CatĂĄlisis y PetroquĂmica ; ArgentinaFil: Spretz, R.. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Santa Fe. Instituto de Investigaciones en CatĂĄlisis y PetroquĂmica ; ArgentinaFil: Lombardo, Eduardo Agustin. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Santa Fe. Instituto de Investigaciones en CatĂĄlisis y PetroquĂmica ; ArgentinaFil: Daniell, W.. Ludwig Maximilians Universitat; AlemaniaFil: Knözinger, H.. Ludwig Maximilians Universitat; Alemani
Oral Delivery of Acid Alpha Glucosidase Epitopes Expressed in Plant Chloroplasts Suppresses Antibody Formation in Treatment of Pompe Mice
Deficiency of acid alpha glucosidase (GAA) causes Pompe disease in which the patients systemically accumulate lysosomal glycogen in muscles and nervous systems, often resulting in infant mortality. Although enzyme replacement therapy (ERT) is effective in treating patients with Pompe disease, formation of antibodies against rhGAA complicates treatment. In this report, we investigated induction of tolerance by oral administration of GAA expressed in chloroplasts. Because full-length GAA could not be expressed, N-terminal 410-amino acids of GAA (as determined by T-cell epitope mapping) were fused with the transmucosal carrier CTB. Tobacco transplastomic lines expressing CTB-GAA were generated through site-specific integration of transgenes into the chloroplast genome. Homoplasmic lines were confirmed by Southern blot analysis. Despite low-level expression of CTB-GAA in chloroplasts, yellow or albino phenotype of transplastomic lines was observed due to binding of GAA to a chloroplast protein that has homology to mannose-6 phosphate receptor. Oral administration of the plant-made CTB-GAA fusion protein even at 330-fold lower dose (1.5 ÎŒg) significantly suppressed immunoglobulin formation against GAA in Pompe mice injected with 500 ÎŒg rhGAA per dose, with several-fold lower titre of GAA-specific IgG1 and IgG2a. Lyophilization increased CTB-GAA concentration by 30-fold (up to 190 ÎŒg per g of freeze-dried leaf material), facilitating long-term storage at room temperature and higher dosage in future investigations. This study provides the first evidence that oral delivery of plant cells is effective in reducing antibody responses in ERT for lysosomal storage disorders facilitating further advances in clinical investigations using plant cell culture system or in vitro propagation
Expression and Assembly of Largest Foreign Protein in Chloroplasts: Oral Delivery of Human FVIII Made in Lettuce Chloroplasts Robustly Suppresses Inhibitor Formation in Haemophilia A Mice
Inhibitor formation is a serious complication of factor VIII (FVIII) replacement therapy for the Xâlinked bleeding disorder haemophilia A and occurs in 20%â30% of patients. No prophylactic tolerance protocol currently exists. Although we reported oral tolerance induction using FVIII domains expressed in tobacco chloroplasts, significant challenges in clinical advancement include expression of the fullâlength CTBâFVIII sequence to cover the entire patient population, regardless of individual CD4+ Tâcell epitope responses. Codon optimization of FVIII heavy chain (HC) and light chain (LC) increased expression 15â to 42âfold higher than the native human genes. Homoplasmic lettuce lines expressed CTB fusion proteins of FVIIIâHC (99.3 kDa), LC (91.8 kDa), C2 (31 kDa) or single chain (SC, 178.2 kDa) up to 3622, 263, 3321 and 852 ÎŒg/g in lyophilized plant cells, when grown in a cGMP hydroponic facility (Fraunhofer). CTBâFVIIIâSC is the largest foreign protein expressed in chloroplasts; despite a large pentamer size (891 kDa), assembly, folding and disulphide bonds were maintained upon lyophilization and longâterm storage as revealed by GM1âganglioside receptor binding assays. Repeated oral gavages (twice/week for 2 months) of CTBâFVIIIâHC/CTBâFVIIIâLC reduced inhibitor titres ~10âfold (average 44 BU/mL to 4.7 BU/mL) in haemophilia A mice. Most importantly, increase in the frequency of circulating LAPâexpressing CD4+ CD25+FoxP3+ Treg in tolerized mice could be used as an important cellular biomarker in human clinical trials for plantâbased oral tolerance induction. In conclusion, this study reports the first clinical candidate for oral tolerance induction that is urgently needed to protect haemophilia A patients receiving FVIII injections
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