Incomplete Diffusion Research Articles

Brain structure and neurological and behavioural functioning in infants born preterm.

To examine: (1) relationships between brain structure, and concurrently assessed neurological and behavioural functioning, in infants born preterm at term-equivalent age (TEA; approximately 38-44wks); and (2) whether brain structure-function relationships differ between infants born very (24-29wks) and moderate-late (32-36wks) preterm. A total of 257 infants (91 very preterm, 166 moderate-late preterm; 120 males, 137 females) had structural magnetic resonance imaging (MRI) and neurological and behavioural assessments (Prechtl's general movements assessment, Neonatal Intensive Care Unit Network Neurobehavioral Scale [NNNS] and Hammersmith Neonatal Neurological Examination [HNNE]). Two hundred and sixty-three infants (90 very preterm, 173 moderate-late preterm; 131 males, 132 females) had diffusion MRI and assessments. Associations were investigated between assessment scores and global brain volumes using linear regressions, regional brain volumes using Voxel-Based Morphometry, and white matter microstructure using Tract-Based Spatial Statistics. Suboptimal scores on some assessments were associated with lower fractional anisotropy and/or higher axial, radial, and mean diffusivities in some tracts: NNNS attention and reflexes, and HNNE total score and tone, were associated with the corpus callosum and optic radiation; NNNS quality of movement with the corona radiata; HNNE abnormal signs with several major tracts. Brain structure-function associations generally did not differ between the very and moderate-late preterm groups. White matter microstructural alterations may be associated with suboptimal neurological and behavioural performance in some domains at TEA in infants born preterm. Brain structure-function relationships are similar for infants born very preterm and moderate-late preterm. Brain volume is not related to neurological/behavioural function in infants born preterm at term. White matter microstructure is related to some neurological/behavioural domains at term. Brain-behaviour relationships are generally similar for infants born very preterm and moderate-late preterm.

Exciton–Phonon Interactions Govern Charge-Transfer-State Dynamics in CdSe/CdTe Two-Dimensional Colloidal Heterostructures

CdSe/CdTe core-crown type-II nanoplatelet heterostructures are two-dimensional semiconductors that have attracted interest for use in light-emitting technologies due to their ease of fabrication, outstanding emission yields, and tunable properties. Despite this, the exciton dynamics of these complex materials, and in particular how they are influenced by phonons, is not yet well understood. Here, we use a combination of femtosecond vibrational spectroscopy, temperature-resolved photoluminescence (PL), and temperature-dependent structural measurements to investigate CdSe/CdTe nanoplatelets with a thickness of four monolayers. We show that charge-transfer (CT) excitons across the CdSe/CdTe interface are formed on two distinct time scales: initially from an ultrafast (∼70 fs) electron transfer and then on longer time scales (∼5 ps) from the diffusion of domain excitons to the interface. We find that the CT excitons are influenced by an interfacial phonon mode at ∼120 cm-1, which localizes them to the interface. Using low-temperature PL spectroscopy we reveal that this same phonon mode is the dominant mechanism in broadening the CT PL. On cooling to 4 K, the total PL quantum yield reaches close to unity, with an ∼85% contribution from CT emission and the remainder from an emissive sub-band-gap state. At room temperature, incomplete diffusion of domain excitons to the interface and scattering between CT excitons and phonons limit the PL quantum yield to ∼50%. Our results provide a detailed picture of the nature of exciton-phonon interactions at the interfaces of 2D heterostructures and explain both the broad shape of the CT PL spectrum and the origin of PL quantum yield losses. Furthermore, they suggest that to maximize the PL quantum yield both improved engineering of the interfacial crystal structure and diffusion of domain excitons to the interface, e.g., by altering the relative core/crown size, are required.

Diffusion and adoption of Integrated Striga Management (ISM) technologies among smallholder maize farmers in rural northern Nigeria

This study estimated the actual and potential adoption rates of Integrated Striga Management (ISM) technologies, among smallholder maize farmers in rural northern Nigeria, using the treatment effect framework. The results revealed a significant overall adoption rate of 55% of the targeted population while 83.5% of the farmers were exposed to the ISM practices. With such an incomplete diffusion of the ISM technologies, the study estimated potential adoption rate to be 68.2%, while the actual adoption (JEA) rate was estimated to be 58.3% resulting in an adoption gap of 9.9% due to incomplete diffusion/exposure. In addition, diffusion and adoption of ISM technologies were found to be influenced by factors such as famer's years of farming experience, total farm size under maize cultivation, cooperative society's membership, attendance of farm workshop/seminars, on-farm trials and field days among others. Policy implications for increase productivity and food security through ISM technology diffusion and adoption were discussed.

Borrowing, incomplete lexical diffusion and the High German tenues shift

Building on Callender 2012, this paper argues that residue from the High German tenues shift may be the result of incomplete lexical diffusion (as opposed to later northern borrowing). Although unshifted forms rarely appear in OHG texts (see Braune 2004 [1886]), an examination of the TITUS corpus and Schützeichel 1995 revealed that their shifted counterparts were also largely absent. This suggests that these forms were simply not the types of words written in OHG texts. Incomplete lexical diffusion thus remains a plausible explanation. I also argue that affrication and spirantization may have been phonologically (perceptually) abrupt. Furthermore, there was little distinction between the two post-vocalically for old short stops, a position where affricates do not survive today.

A phenomenological study of yttria-stabilized zirconia at 1300 K with the Green-Kubo formulation and equilibrium molecular dynamics

In this study, we analyze the transport mechanisms in different yttria-stabilized zirconia compositions as an example for an ionic solid at 1300K and zero pressure with EMD and the Green-Kubo formulation. As it can be interpreted from the partial and the total correlation functions of the micro fluxes, a certain amount of anions should be given to activate the diffusion of other anions. An incomplete vacancy diffusion favors the coupled effect of heat and diffusion. The heat conduction decreases for higher concentration of vacancies and the optimum of the diffusion is reproducible with this method. We predict a minimum of the thermo-diffusion conductivity at 10mol% Y2O3. The understanding of the heat and electrical conduction of ionic solids and of the couple effect is essential in systems, where the gradients of different kind of forces are present.

Clinicoradiologic features distinguish tumefactive multiple sclerosis from CNS neoplasms.

There are limited data to guide clinicians in differentiating tumefactive multiple sclerosis (TMS) from CNS neoplasms. Identifying distinguishing features will inform diagnosis and management and avoid unnecessary diagnostic biopsy. Our study aimed to determine the clinical and radiologic features that differentiate TMS from glioma and CNS lymphoma (CNSL) in patients who present with tumefactive lesions. We retrospectively reviewed all patients with tumefactive lesions and histologically proven or clinically diagnosed TMS, glioma, or CNSL at our tertiary center from 1999 to 2012. Two independent blinded neuroradiologists rated MRI brain scans at presentation. We correlated patients' demographic, clinical, laboratory, and radiologic data to final diagnosis. A total of 133 patients (10 TMS, 85 glioma, 38 CNSL) were analyzed. Patients with TMS were younger and a greater proportion were women. Presenting symptoms did not distinguish between diagnoses. TMS lesions were smaller compared to glioma and CNSL, had no or mild mass effect, and were always associated with contrast enhancement. Radiologic features that were more frequent in TMS lesions were incomplete rim (open-ring) enhancement, incomplete peripheral diffusion restriction, and mixed T2 signal and CT hypoattenuation of MRI-enhancing components (all p < 0.05). Radiologic features but not presenting symptoms are useful in distinguishing TMS from CNS neoplasms.

A kinetic equation for economic value estimation with irrationality and herding

A kinetic inhomogeneous Boltzmann-type equation is proposed to model the dynamics of the number of agents in a large market depending on the estimated value of an asset and the rationality of the agents. The interaction rules take into account the interplay of the agents with sources of public information, herding phenomena, and irrationality of the individuals. In the formal grazing collision limit, a nonlinear nonlocal Fokker-Planck equation with anisotropic (or incomplete) diffusion is derived. The existence of global-in-time weak solutions to the Fokker-Planck initial-boundary-value problem is proved. Numerical experiments for the Boltzmann equation highlight the importance of the reliability of public information in the formation of bubbles and crashes. The use of Bollinger bands in the simulations shows how herding may lead to strong trends with low volatility of the asset prices, but eventually also to abrupt corrections.

Intermetallic layer obtained by the compact powder diffusion alloying method on AZ91D magnesium alloy in air

Abstract Compact powder diffusion alloying process has been carried out on AZ91D magnesium specimens at 430 °C in air atmosphere. After the sole diffusion alloying process, only partially alloyed surface was obtained, and this was attributed to the incomplete diffusion alloying process. Moreover, formation of the MgO film caused weight loss of the overall specimen, and the weight loss phenomenon is also related to the initiation and growth of cracks at edges and/or corners of some specimens. Repeated diffusion alloying processes after eliminating the MgO film and adding new diffusion source allowed the Al atom diffusion process to continue. By this method, a more complete intermetallic coating was obtained.

Synthesis of Ti–Ta alloys with dual structure by incomplete diffusion between elemental powders

In this work, powder metallurgical (PM) Ti–Ta alloys were sintered using blended elemental powders. A dual structure, consisting of Ti-rich and Ta-rich zones, was formed due to the insufficient diffusion between Ti and Ta powders. The microstructure, mechanical properties and in vitro biological properties of the alloys were studied. Results indicated that the alloys have inhomogenous microstructures and compositions, but the grain structures were continuous from the Ti-rich zone to the Ta-rich zone. The Ta-rich zone exhibited a much finer grain size than the Ti-rich zone. The alloys had a high relative density in the range of 95–98%, with the porosity increasing with the content of Ta due to the increased difficulty in sintering and the formation of Kirkendall pores. The alloys had a good combination of low elastic modulus and high tensile strength. The strength of alloys was almost doubled compared to that of the ingot metallurgy alloys with the same compositions. The low elastic modulus was due to the residual pores and the alloying effect of Ta, while the high tensile strength resulted from the strengthening effects of solid solution, fine grain size and α phase. The alloys had a high biocompatibility due to the addition of Ta, and were suitable for the attachment of cells due to the surface porosity. It was also indicated that PM Ti–(20–30)Ta alloys are promising for biomedical applications after the evaluations of both the mechanical and the biological properties.

Optimal investment under behavioral criteria in incomplete diffusion market models

Устанавливается существование оптимальной стратегии для поведенческого инвестора в модели неполного рынка с непрерывным временем.

Exploiting the Incomplete Diffusion Feature: A Specialized Analytical Side-Channel Attack Against the AES and Its Application to Microcontroller Implementations

Algebraic side-channel attack (ASCA) is a typical technique that relies on a general solver to solve the equations of a cipher and its side-channel leaks. It falls under analytical side-channel attack and can recover the entire key at once. Many ASCAs are proposed against the AES, and they utilize the Grobner basis-based, SAT-based, or optimizer-based solver. The advantage of the general solver approach is its generic feature, which can be easily applied to different cryptographic algorithms. The disadvantage is that it is difficult to take into account the specialized properties of the targeted cryptographic algorithms. The results vary depending on what type of solver is used, and the time complexity is quite high when considering the error-tolerant attack scenarios. Thus, we were motivated to find a new approach that would lessen the influence of the general solver and reduce the time complexity of ASCA. This paper proposes a new analytical side-channel attack on AES by exploiting the incomplete diffusion feature in one AES round. We named our technique incomplete diffusion analytical side-channel analysis (IDASCA). Different from previous ASCAs, IDASCA adopts a specialized approach to recover the secret key of AES instead of the general solver. Extensive attacks are performed against the software implementation of AES on an 8-bit microcontroller. Experimental results show that: 1) IDASCA can exploit the side-channel leaks in all AES rounds using a single power trace; 2) it has less time complexity and more robustness than previous ASCAs, especially when considering the error-tolerant attack scenarios; and 3) it can calculate the reduced key search space of AES for the given amount of side-channel leaks. IDASCA can also interpret the mechanism behind previous ASCAs on AES from a quantitative perspective, such as why ASCA can work under unknown plaintext/ciphertext scenarios and what are the extreme cases in ASCAs.

Layerwise decomposition of water dynamics in reverse micelles: A simulation study of two-dimensional infrared spectrum

We present computer simulation study of two-dimensional infrared spectroscopy (2D-IR) of water confined in reverse micelles (RMs) of various sizes. The present study is motivated by the need to understand the altered dynamics of confined water by performing layerwise decomposition of water, with an aim to quantify the relative contributions of different layers water molecules to the calculated 2D-IR spectrum. The 0-1 transition spectra clearly show substantial elongation, due to inhomogeneous broadening and incomplete spectral diffusion, along the diagonal in the surface water layer of different sized RMs. Fitting of the frequency fluctuation correlation functions reveal that the motion of the surface water molecules is sub-diffusive and indicate the constrained nature of their dynamics. This is further supported by two peak nature of the angular analogue of van Hove correlation function. With increasing system size, the water molecules become more diffusive in nature and spectral diffusion almost completes in the central layer of the larger size RMs. Comparisons between experiments and simulations establish the correspondence between the spectral decomposition available in experiments with the spatial decomposition available in simulations. Simulations also allow a quantitative exploration of the relative role of water, sodium ions, and sulfonate head groups in vibrational dephasing. Interestingly, the negative cross correlation between force on oxygen and hydrogen of O-H bond in bulk water significantly decreases in the surface layer of each RM. This negative cross correlation gradually increases in the central water pool with increasing RMs size and this is found to be partly responsible for the faster relaxation rate of water in the central pool.

Volume transmission and its different forms in the central nervous system

Volume transmission (VT) is a widespread mode of intercellular communication that occurs in the extracellular fluid (ECF) and in the cerebrospinal fluid (CSF) of the brain with VT signals moving from source to target cells via energy gradients leading to diffusion and convection (flow). The VT channels are diffuse forming a plexus in the extracellular space, while in wiring transmission (WT) the channels (axons, terminals) are private. The speed is slow (seconds-minutes) in VT while rapid in the millisecond range in WT. The extracellular space is the substrate for VT, which is modulated by the extracellular matrix. Extrasynaptic VT is linked to synaptic transmission and likely often takes place due to incomplete diffusion barriers with the synaptic transmitter reaching extrasynaptic domains of the pre-and post-synaptic membrane of the synapse, the astroglia, and even adjacent synapses. Indications exist for the existence of striatal D2-like receptor-mediated extrasynaptic form of dopamine (DA) VT at the local circuit level in vivo in the human striatum. Synaptic glutamate via extrasynaptic VT can act on extrasynaptic metabotropic glutamate receptors located on the astroglia leading to Ca(2+) mediated astrocytic glutamate release into the extracellular space (ECS). Long distance peptide VT and CSF VT is the major long distance VT with distances more than 1 mm and flow in the CSF. Indications for long distance VT of beta-endorphin and oxytocin are obtained. We propose that monogamy in the female prairie vole may take place through an increase in oxytocin VT, especially in nucleus accumbens. Release of extracellular vesicles containing receptors, proteins, RNAs and mtDNA from cellular networks in the central nervous system (CNS) into the ECF and CSF may be a fundamental communication in the CNS. It represents a special form of volume transmission, the Roamer subtype of VT. It may greatly contribute to dynamic events of synaptic plasticity but also to spread of pathological proteins in protein conformational disorders. VT also occurs in the peripheral nervous system and associated cells. Short and long distance VT may take place in meridian channels via diffusion and flow in the interstitial fluid. Acupuncture can produce VT signals by releasing transmitters and modulators from nerve terminals and mast cells.

A novel CD44v6 targeting antibody fragment with improved tumor-to-blood ratio

The chimeric monoclonal antibody U36 (cMAb U36) recognizes the CD44v6 antigen. Its potential as a radioimmunotargeting agent, as well as its safety, has been shown in previous studies in head and neck cancer patients. However, intact MAbs have long circulation time in the blood and tumor targeting may also be hampered due to the slow and incomplete diffusion into solid tumors. In comparison, smaller monovalent Fab' and divalent F(ab')2 fragments are expected to exhibit shorter circulating half-lives, better tumor penetration and are thus more likely to yield better imaging results. In this study, novel F(ab')2 and Fab' fragments from cMAb U36 were radiolabeled with 125I and the characteristics of the conjugates invitro were examined. The biodistribution of the conjugates were then evaluated in nude mice bearing CD44v6-expressing xenograft tumors. Furthermore, the penetration depth and distribution in tumor tissue was assessed by autoradiography in selected tumor samples. The invitro experiments showed that the conjugates were stable and had intact affinity to CD44v6. The biodistribution study demonstrated superior tumor-to-blood ratio for the novel cMAb U36 fragment 125I-F(ab')2 compared with both the intact MAb and the monovalent fragment form. Autoradiography also revealed better tumor penetration for 125I-F(ab')2. This study demonstrates that the use of antibody fragments may improve radioimmunotargeting and possibly improve the management of head and neck malignancies.

Determinants of diffusion and adoption of improved technology for rice parboiling in Benin

The widespread use of traditional rice-parboiling methods in Benin leads to poor quality of final rice. To address this problem, the national agricultural research institute of Benin and Africa Rice Center have developed improved rice parboiling technology. An educational video developed by AfricaRice was used for it diffusion. Women have expressed high interest in the use of the technology and have reported that it helps increase the quality of their final rice despite its' relatively high cost. This paper uses the Average Treatment Effect (ATE) framework and data collected from 200 women rice parboilers in central Benin to estimate the actual and potential adoption rates of this technology and the determinants of its diffusion and adoption. 85% of the sampled women were exposed to the technology in 2008. With this incomplete diffusion, the actual adoption rate is 67%, whereas the potential adoption rate is estimated to be 75%. Being member of a parboilers association'' and Participation in video are positively associated with knowledge and adoption of this technology. This indicates that support and promotion of women parboilers associations is a means to increase technology uptake and access and video-supported training is an extension tool to promote agricultural technology awareness and adoption.

Effects of processing and powder size on microstructure and reactivity in arrested reactive milled Al + Ni

Ball-milling Al-metal powders can result in self-sustaining high-temperature synthesis in intermetallic-forming systems. Here, Al and Ni powders with similar composition are used to investigate how microstructural differences affect the measured time to reaction (TTR) between powders of different sizes processed under milling conditions specified by statistically designed experiments. Linear statistical models predicting the TTR and the change in temperature (Δ T) are built from these experimental results. The time required to observe a self-sustained high-temperature synthesis of NiAl with different combinations of the powders and ball-milling conditions vary by almost an order of magnitude. Comparisons of powders milled to times corresponding to percentages of their averaged TTR show similar reaction initiation temperatures despite the difference in total milling time. Several distinct arrested reactions within the powder grains exhibit rapid solidification or incomplete diffusion of Ni into Al, forming porous Ni-rich layered structures. The partially reacted grains suggest that the composite laminate particles are not forming intermetallic on the grain scale, but on the localized scale between layers.

Adsorption of Organophosphates into Microporous and Mesoporous NaX Zeolites and Subsequent Chemistry

Due to the neurotoxicity of organophosphate (OP) pesticides and nerve agents synthesized as military or terror agents, their safe destruction and disposal is of considerable current importance. A representative OP, trimethyl phosphate (TMP), was adsorbed onto NaX zeolite, two mesoporous modifications, and a low-silica X zeolite. The nucleophilic chemical reactions of TMP with the zeolites were investigated by solid-state 13C and 31P nuclear magnetic resonance (NMR) and the solvent extracts by 1H, 13C, and 31P NMR. Nucleophilic substitution and subsequent hydrolysis reaction schemes are proposed. All of the zeolites have similar TMP decomposition yields, supporting the hypothesis that slow or incomplete diffusion of TMP in the microporous zeolite regions limits TMP decomposition.

Oxidation and fusion defects synergistically accelerate polyethylene failure in knee replacement

We have previously reported upon a cohort of patients with premature failure of such material and postulated upon the impact of abnormally high concentrations of type 2 fusion defects whereby there is a lack of particle cohesion due to incomplete diffusion. In vivo oxidation has been purported to underscore the premature failure of polyethylene. The mechanism of such remains poorly delineated. New data has now been obtained by determining substrata oxidative profiles of 10 failed Kinemax Plus modular tibial insert analyses in conjunction with fusion defect detection. The full thickness of a series of cores was analysed using infra-red spectroscopy to identify higher levels of oxidation in loaded used material at both the articulating and non-articulating regions. A comparison was made to an unused control. Articulating, loaded, areas exhibited greater local concentrations of oxidised material and wider variation of such consistent with the higher presence of fusion defects. Subsurface analysis confirmed the presence of a major oxidative peak 2mm below the surface for all loaded areas irrespective of wear. Additionally we were able to identify a second major oxidative focus about halfway between the inferior (tibial baseplate) surface and the articulating area. We believe that the combination of high oxidation and fusion defects represents a second high stress zone consistent with the observation of tibial baseplate polyethylene dissociation and backside wear with resultant catastrophic material failure.

Effect of binder content on relative density, microstructure and properties of complex cemented carbides obtained by thermal explosion-pressing

Combustion in thermal explosion mode of the mixtures (Ti–Cr–Mo–W-graphite) under low uniaxial pressure of 19 MPa was used to produce cemented carbides (complex carbides/iron–nickel alloy). The results of the investigations showed that ignition ( T ign) and combustion ( T max) temperatures, as well as material density, structure and properties, were sensitive to the iron–nickel additions. When the iron–nickel content increases, combustion is characterized by a lowering from T ign and a reduction in reactions heating effect. The carbide formation was carried out by selective mechanism. Carbides of titanium (TiC) and chromium (Cr 23C 6) were formed instantaneously during the exothermic peak. However, the molybdenum carbide (Mo 2C) and mainly the tungsten carbide (W 2C) resulted from incomplete carbon diffusion in solid state. An isothermal maintenance under pressure at 1373 K, has allowed to accelerate the material densification mechanisms by viscous flow. At the same time, it completed the carbides formation thanks to the carbon diffusion mechanism as shown by the presence of new phases such as WC and Cr 7C 3. The maximum effect of densification was observed for a binder content of 50 wt.%, where the relative density of product attained 95%. The Vickers hardness (HV 0.15) depends also on the binder content and varies from 6300 MPa to 19,000 MPa. The best tribological behaviour was achieved on cermets with 30% (Fe–Ni).

Low Energy Ion Scattering Investigations of n-Butanol−Ice System in the Temperature Range of 110−150 K

We have investigated the interaction of n-butanol (NBA) with thin layers of water ice prepared in ultra high vacuum in the temperature range of 110−150 K. From the mass spectra of the chemically sputtered species, created upon the collision of low energy (≥30 eV) Ar+ ions, we study the process of diffusive mixing of NBA with water ice, at the molecular level. The results show that NBA undergoes diffusive mixing with H2O. Even after depositing 1000 monolayers (MLs) of amorphous solid water (ASW) over NBA, both the species are observed on the surface. However, when NBA is deposited over ASW, no water is seen on the surface above 3−5 MLs of NBA. This could be interpreted as the absence of diffusive mixing in this system or surface segregation of NBA, in view of its lower surface energy just as in the case of liquid alcohols. An isomeric alcohol, namely, tert-butyl alcohol (TBA), also behaves similarly. Although the presence of NBA and TBA is detected, in the presence of ASW, they undergo selective ionization, giving specific peaks in the mass spectrum. D2O behaves in a manner similar to that of H2O. Preliminary experiments with other alcohols; namely, methanol, ethanol, and propanol were also done, and the results suggest that incomplete diffusion or surface segregation begins with propanol.