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Introduction: The Ottawa SAH Rule was developed to identify patients at high-risk for subarachnoid hemorrhage (SAH) who require investigations and the 6-Hour CT Rule found that computed tomography (CT) was 100% sensitive for SAH 6 hours of headache onset. Together, they form the Ottawa SAH Strategy. Our objectives were to assess: 1) Safety of the Ottawa SAH Strategy and its 2) Impact on: a) CTs, b) LPs, c) ED length of stay, and d) CT angiography (CTA). Methods: We conducted a multicentre prospective before/after study at 6 tertiary-care EDs January 2010 to December 2016 (implementation July 2013). Consecutive alert, neurologically intact adults with a headache peaking within one hour were included. SAH was defined by subarachnoid blood on head CT (radiologists final report); xanthochromia in the cerebrospinal fluid (CSF); >1x106/L red blood cells in the final tube of CSF with an aneurysm on CTA. Results: We enrolled 3,669 patients, 1,743 before and 1,926 after implementation, including 185 with SAH. The investigation rate before implementation was 89.0% (range 82.9 to 95.6%) versus 88.4% (range 85.2 to 92.3%) after implementation. The proportion who had CT remained stable (88.0% versus 87.4%; p=0.60), while the proportion who had LP decreased from 38.9% to 25.9% (p<0.001), and the proportion investigated with CTA increased from 18.8% to 21.6% (p=0.036). The additional testing rate (i.e. LP or CTA) diminishedfrom 50.1% to 40.8% (p<0.001). The proportion admitted declined from 9.8% to 7.3% (p=0.008), while the mean length of ED stay was stable (6.2 +/− 4.0 to 6.4 +/− 4.1 hours; p=0.45). For the 1,201 patients with CT 6 hours, there was an absolute decrease in additional testing (i.e. LP or CTA) of 15.0% (46.6% versus 31.6%; p<0.001). The sensitivity of the Ottawa SAH Rule was 100% (95%CI: 98-100%), and the 6-Hour CT Rule was 95.3% (95%CI: 88.9-98.3) for SAH. Five patients with early CT had SAH with CT reported as normal: 2 unruptured aneuryms on CTA and presumed traumatic LP (determined by treating neurosurgeon); 1 missed by the radiologist on the initial interpretation; 1 dural vein fistula (i.e. non-aneuyrsmal); and 1 profoundly anemic (Hgb 63g/L). Conclusion: The Ottawa SAH Strategy is highly sensitive and can be used routinely when SAH is being considered in alert and neurologically intact headache patients. Its implementation was associated with a decrease in LPs and admissions to hospital.
Children reared in impoverished environments are at risk for enduring psychological and physical health problems. Mechanisms by which poverty affects development, however, remain unclear. To explore one potential mechanism of poverty's impact on social–emotional and cognitive development, an experimental examination of a rodent model of scarcity-adversity was conducted and compared to results from a longitudinal study of human infants and families followed from birth (N = 1,292) who faced high levels of poverty-related scarcity-adversity. Cross-species results supported the hypothesis that altered caregiving is one pathway by which poverty adversely impacts development. Rodent mothers assigned to the scarcity-adversity condition exhibited decreased sensitive parenting and increased negative parenting relative to mothers assigned to the control condition. Furthermore, scarcity-adversity reared pups exhibited decreased developmental competence as indicated by disrupted nipple attachment, distress vocalization when in physical contact with an anesthetized mother, and reduced preference for maternal odor with corresponding changes in brain activation. Human results indicated that scarcity-adversity was inversely correlated with sensitive parenting and positively correlated with negative parenting, and that parenting fully mediated the association of poverty-related risk with infant indicators of developmental competence. Findings are discussed from the perspective of the usefulness of bidirectional–translational research to inform interventions for at-risk families.
Experiments on the National Ignition Facility show that multi-dimensional effects currently dominate the implosion performance. Low mode implosion symmetry and hydrodynamic instabilities seeded by capsule mounting features appear to be two key limiting factors for implosion performance. One reason these factors have a large impact on the performance of inertial confinement fusion implosions is the high convergence required to achieve high fusion gains. To tackle these problems, a predictable implosion platform is needed meaning experiments must trade-off high gain for performance. LANL has adopted three main approaches to develop a one-dimensional (1D) implosion platform where 1D means measured yield over the 1D clean calculation. A high adiabat, low convergence platform is being developed using beryllium capsules enabling larger case-to-capsule ratios to improve symmetry. The second approach is liquid fuel layers using wetted foam targets. With liquid fuel layers, the implosion convergence can be controlled via the initial vapor pressure set by the target fielding temperature. The last method is double shell targets. For double shells, the smaller inner shell houses the DT fuel and the convergence of this cavity is relatively small compared to hot spot ignition. However, double shell targets have a different set of trade-off versus advantages. Details for each of these approaches are described.
Comparing genotype results of tuberculosis (TB) isolates from individuals diagnosed with TB can support or refute transmission; however, these conclusions are based upon the criteria used to define a genotype match. We used a genotype-match definition which allowed for variation in IS6110 restriction fragment length polymorphism (RFLP) to support transmission between epidemiologically linked persons. Contacts of individuals with infectious TB (index cases) diagnosed in New York City from 1997 to 2003 who subsequently developed TB (contact cases) from 1997 to 2007 were identified. For each contact case and index case (case-pair), isolate genotypes (spoligotype and RFLP results) were evaluated. Isolates from case-pairs were classified as exact or non-exact genotype match. Genotypes from non-exact match case-pairs were reviewed at the genotyping laboratory to determine if the isolates met the near-genotype-match criteria (exactly matching spoligotype and similar RFLP banding patterns). Of 118 case-pairs identified, isolates from 83 (70%) had exactly matching genotypes and 14 (12%) had nearly matching genotypes (supporting transmission), while the remaining 21 (18%) case-pairs had discordant genotypes (refuting transmission). Using identical genotype-match criteria for isolates from case-pairs epidemiologically linked through contact investigation may lead to underestimation of transmission. TB programmes should consider the value of expanding genotype-match criteria to more accurately assess transmission between such cases.
Improving neurocognitive outcomes following treatment for brain metastases have become increasingly important. We propose that a brief telephone-based neurocognitive assessment may improve follow-up cognitive assessments in this palliative population. Aim: To prospectively assess the feasibility and reliability of a telephone based brief neurocognitive assessment compared to the same tests delivered face-to-face. Methods: Brain metastases patients to be treated with whole brain radiotherapy (WBRT) were assessed using a brief validated neurocognitive battery at baseline, at 1 month and 3 months following WBRT (in person and over the phone). The primary outcome was feasibility and inter-procedural (in person versus telephone) reliability. The secondary objective was to evaluate the change in neurocognitive function before and after WBRT. Results: Out of 39 patients enrolled, 82% of patients completed the baseline in-person and telephone neurocognitive assessments. However, at 1 month, only 41% of enrolled patients completed the in-person and telephone cognitive assessments and at 3 months, only 10% of patients completed them. Results pertaining to reliability and change in neurocognitive function will be updated. Conclusion: The pre-defined definition of feasibility (at least 80% completion for face to face and telephone neurocognitive assessments) was met at baseline. However, a large proportion of participants did not complete either telephone or in person neurocognitive follow-up at 1 month and at 3 months post-WBRT. Attrition remained a challenge for neurocognitive testing in this population even when a telephone-based brief assessment was used.
The aim of this preliminary study was to adapt Layer-by-Layer (LbL) assembly to fabricate nanocomposite coatings onto open-cell porous structures, enabling customization of mechanical properties and porosity to obtain materials suitable for bone tissue scaffold applications. LbL assembly is a well-established method for fabricating multilayer films with nanometre scale precision over thickness that is based on electrostatic attractions and involves the adsorption of oppositely charged electrolytes onto a substrate. Using LbL assembly, polymer-nanoclay composite coatings were deposited onto open-cell foam substrates. The elastic modulus of coated specimens in compression was improved from 0.078 MPa to 1.736 MPa. The results suggest that polymer-nanoclay coatings deposited via LbL assembly have the potential to improve mechanical properties of porous substrates and fabricate materials with mechanical properties comparable to that of a cancellous bone tissue upon deposition of a sufficient number of multilayers.
Cellulose is one of the most abundant substances in the world, and the major constituent in the wood structure. Phenolic adhesive is largely used in the wood manufacture for gluing the wood panels together. The cellulose/phenolic adhesive interface is a representative of the interface between the wood panels and adhesives in the wood products. As the wood panels and adhesive are sensitive to environmental humidity, the interfacial adhesion of such interface when subjected to a humid environment can be a major factor in the durability of final products. Here, the role of water molecules on the adhesion property of cellulose/phenolic adhesive interface is investigated by molecular dynamics simulations. The simulation results reveal that the adhesion energy between cellulose and phenolic adhesive can be reduced by 86.5% with saturated moisture ingress. Meanwhile, it is demonstrated that the adhesion energy can be recovered after the interface experiences further dry conditioning. The hydrogen bonds between the cellulose and phenolic adhesive are found to account for the strong interfacial adhesion, which can be interrupted in the presence of water molecules and recovered after further dry conditioning. The adhesion property between the wood panels and adhesives is mainly determined by water molecules absorbed at the bilayer interface, which should be considered in a wet condition.
The antibacterial properties of boron-containing compounds are well known although there are limited studies available on the pure boron nanoparticles. In this study boron nano-particles were characterized in terms of their particle size, shape, stability and surface charge before and after they are applied to textile surfaces to study their impact on antibacterial activity in addition to cytotoxicity. It was observed that the boron nano-particles are affective in limiting bacteria growth on both gram-negative and gram-positive species without requiring any stimulation to initiate the antibacterial action. It was also found that the application of boron nano-particles on the textile surfaces through mixing them in hydrophobic finishing solutions helped improve the wettability performance of the textiles while showing no change in the physical and colour fastness properties at an optimal concentration of 0.02 % w/v of finishing solution.
We report the development of a label-free biosensors based on DNA hybridization, using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). This study uses DNA sequences based on microRNA related with breast cancer. The biosensor was fabricated by immobilizing a self-assembled monolayer of single-stranded 23-mer oligonucleotide (ssDNA) via a thiol linker on gold work electrodes. Residual binding places were filled with 6 -mercaptohexanol (MCH). The electrode was electrochemicaly characterized in the presence of a redox system ferri/ferrocyanide. Different concentrations of complementary DNA sequence for hybridization were incubated; an increase of charge transfer resistance (Rct) was observed, used as sensor parameter and correlated with concentrations of complementary DNA sequence. A debate was presented on the effect of the MgCl2 influence on ssDNA immobilization solution.
Using a combination of x-ray diffraction, volumetric adsorption and inelastic neutron scattering (INS) the adsorption properties of methane within the channels of L-Isoleucyl-L-Valine (IV) and L-Valyl-L-Alanine (VA) dipeptides have been investigated. These biomaterials have quasi one-dimensional channels of tunable diameters in the range of 3-6 Å and offer possibilities for selective adsorption, as well as, water and gas transport properties. High-resolution volumetric methane adsorption measurements performed near 100K for IV find that this biomaterial exhibits an adsorption capacity of ∼100 m2/g. High-resolution Inelastic Neutron Scattering (INS) measurements were performed at the Spallation Neutron Source using the BASIS spectrometer with ∼ 3.5 μeV resolution. The data clearly indicate that at least two spectral features at energy transfers near 100 and 200 μeV are present, which suggests a lowering of the hindering potential for methane reorientation primarily about the three-fold axis within the IV channels. Such features play a key role in understanding details concerning the potential energy surface. These thermodynamic and INS studies suggest that the flexibility and dynamical motion within the dipeptide channels may play a significant role in the adsorption properties.
We report optically active ensembles of II-VI semiconductor nanocrystals prepared via chiral phase transfer, which is initiated by exchange of the original achiral ligands capping the nanocrystals surfaces for chiral L- and D-cysteine. We used this method to obtain ensembles of CdSe, CdS, ZnS:Mn, and CdSe/ZnS quantum dots and CdSe/CdS quantum rods exhibited Circular Dichroism (CD) and Circularly Polarized Luminescence (CPL) signals. The optically active nanocrystals revealed the CD and CPL bands strongly correlated with absorption and luminescence bands with unique band “pattern” for each material and the nanocrystal shape.
The surfaces of inorganic substrates containing hydroxyl groups can be adapted to a variety of physical and chemical requirements by reaction with cyclic azasilanes. The moderately-strained ring structure of cyclic azasilanes containing adjacent Si and N atoms, along with the high oxophilicity of silicon, enables the high reactivity towards available hydroxyl groups on all siliceous surfaces investigated, including amorphous silica and borosilicate glass. The reaction occurs quantitatively at room temperature, requires no catalyst and has no byproducts. This investigation looks specifically at the reaction kinetics by means of DRIFT spectroscopy and quantifies extent of reaction by TGA. The less sterically-hindered the Si–N bond, the faster the reaction occurs. In all cases, the reaction is essentially complete in less than one minute. This study provides the first confirmation that the rate and extent of reaction without catalysis or byproducts of cyclic azasilanes conforms to the Sharpless requirements for “click chemistry” and can be deemed “click chemistry for surfaces.”
Understanding the interaction of water with biological materials is of fundamental importance. One of main driving forces behind the renewed activity of biomimetic materials involves the dramatic physical properties that many of them exhibit. Two main factors that are critical for understanding silks: the nanoscale semi-crystalline folding structure, and the degree of hydration of the disordered fraction. We describe our investigation of the preparation, characterization and inelastic neutron scattering (INS) studies of the microscopic dynamics of natural Bombyx mori silk fibroin proteins derived from silkworm cocoons. An in situ quartz microbalance is used for monitoring/controlling the hydration and solvent levels of the proteins electrospun onto neutron sample holders. By employing these novel methods our INS investigation facilitated a snapshot of the microscopic silk protein dynamics heretofore not investigated or reported. Preliminary INS measurements illustrate the effect of water and methanol interaction on the dynamics of the fibroin β-pleated sheet component. Evidence of what appears to be a water component (intersheet) distinct from bulk water is clearly apparent in the INS spectrum when the dynamical response from the dry silk is subtracted away.
An urgent need exist for developing handheld devices for rapid, sensitive, and specific detection method for pathogens. Here we demonstrate a rapid detection method for Gram-positive and Gram-negative bacteria using an impedance sensor array functionalized with antimicrobial peptides (AMPs). This impedance sensor screens pathogens in real-time and has comparable sensitivity with current detection methods like polymerase chain reaction (PCR) and immunoassay. Functionalized electrodes in array selectively bind to the corresponding bacteria strains, resulting in variations in the impedance modulus. Impedance variation is used to detect incubated bacterial cell concentration with a resolution of 1 cell µL-1. The dynamic range of detection for both Gram-positive and Gram-negative bacteria is found to be 103-106 cfu mL-1. Micropatterned electrodes modified with AMPs in an impedimetric array offer an excellent platform for rapid and selective detection of pathogens in contaminated water and food products.
We present herein a joint physical/physico-chemical study and, more specifically, the first application of Matrix Assisted Laser Desorption Ionization coupled with Time of Flight Mass Spectrometry (MALDI-TOF-MS) to analyze small-sized ZnO quantum dots (QDs) (2.8-3.1 nm diameter range) synthesized by sol-gel chemistry and stabilized through an aminosilane coating. A careful investigation of the stability of ZnO QDs was initiated once these dots were dispersed in different media (water, biological buffer) for a period up to 3 weeks. Positive ion mode mass spectra MALDI-TOF-MS combined with optical spectrometry was used to monitor the stability of ZnO QDs when aging. Such a unique combination of MALDI-TOF-MS and physico-chemical techniques is likely to bring new insights into the structure analysis, the stability and consequently the potential toxicity of QDs.
We introduce a sensing element, “Molecularly Imprinted Polymer (MIP),” which created by “Molecular Imprinted Technique.” However, the sensitivity of MIP’s based bio-sensors limits for practical applications due to the low sensitivity. To achieve a high sensitivity of MIP’s based sensors, the synthesis of “high affinity receptor or binding sites,” such as “monoclonal particles” is a key objective. In previous studies, affinity distribution plots indicated that “high affinity binding sites” were obtained when the number of binding sites per particle decreased. It means that smaller particles are expected to have higher affinity binding sites compared to larger particles. The result motivated us to produce small-sized MIP’s particles for the achievement of higher sensitivity. Microfluidic Synthesis has taken a great attention to synthesize small particles. However, the microfluidic synthesis gave us a difficulty, especially collections of MIP’s particles from the surface of PDMS-based microchannels due to a sticking problem. Thus, we employed a new approach, which can collect MIP’s particles without any sticking problem from the surface of the reactor. It is a photopatterned MIP’s system generated on the glass surface. We prepared a photomask with micro-sized patterns and then fabricate MIP’s particles on a glass surface by photopolymerization. Uniform MIP’s patterns were printed on the glass surface. The interface between the glass surface and the MIP’s pattern was observed by SEM. Micro-sized MIP’s particles were collected from the glass surface by scratching off the photocured MIP’s patterns.