National Bureau of Economic Research

National Bureau of Economic Research

A new imaging technique may give researchers fresh insights into brain development, function, and disease

The human brain is often said to be the most complex object in the known universe, and there’s good reason to believe that it is. That lump of jelly inside your head contains at least 80 billion nerve cells, or neurons, and even more of the non-neuronal cells called glia. Between them, they form hundreds of trillions of precise synaptic connections; but they all have moveable parts, and these connections can change. Neurons can extend and retract their delicate fibres; some types of glial cells can crawl through the brain; and neurons and glia routinely work together to create new connections and eliminate old ones.

These processes begin before we are born, and occur until we die, making the brain a highly dynamic organ that undergoes continuous change throughout life. At any given moment, many millions of them are being modified in one way or another, to reshape the brain’s circuitry in response to our daily experiences. Researchers at Yale University have now developed an imaging technique that enables them to visualise the density of synapses in the living human brain, and offers a promising new way of studying how the organ develops and functions, and also how it deteriorates in various neurological and psychiatric conditions.

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Contributions of experimental and selected theoretical charge-density research to medicinal chemistry are reviewed; combining experimental methods from high-resolution small-molecule and macromolecular crystallography with theory proves to be fruitful.

The present work reports on the charge and spin density modelling of YTiO3 in its ferromagnetic state (TC = 27 K). Accurate polarized neutron diffraction and high-resolution X-ray diffraction (XRD) experiments were carried out on a single crystal at the ORPHÉE reactor (LLB) and SPRING8 synchrotron source. The experimental data are modelled by the spin resolved pseudo-atomic multipolar model (Deutsch et al., 2012). The refinement strategy is discussed and the result of this electron density modelling is compared with that from XRD measured at 100 K and with density functional theory calculations. The results show that the spin and charge densities around the Ti atom have lobes directed away from the O atoms, confirming the filling of the t2g orbitals of the Ti atom. The dxy orbital is less populated than dxz and dyz, which is a sign of a partial lift of degeneracy of the t2g orbitals. This study confirms the orbital ordering at low temperature (20 K), which is already present in the paramagnetic state above the ferromagnetic transition (100 K).

High-resolution single-crystal X-ray measurements of the monoclinic polymorph of bicalutamide and the aspherical atom databank approach have served as a basis for a reconstruction of the charge density distribution of the drug and its androgen receptor (AR) and albumin complexes. The contributions of various types of intermolecular interactions to the total crystal energy or ligand:AR energy were estimated. The cyan and amide groups secured the ligand placement in the albumin (Lys-137) and the AR binding pocket (Leu-704, Asn-705, Arg-752), and also determined the packing of the small-molecule crystals. The total electrostatic interaction energy on average was −230 kJ mol−1, comparable with the electrostatic lattice energy of the monoclinic bicalutamide polymorph. This is the result of similar distributions of electropositive and electronegative regions on the experimental and theoretical molecular electrostatic potential maps despite differences in molecular conformations. In general, bicalutamide interacted with the studied proteins with similar electrostatic interaction energies and adjusted its conformation and electrostatic potential to fit the binding pocket in such a way as to enhance the interactions, e.g. hydrogen bonds and π⋯π stacking.

Single crystals of the m = 8 member of the low-dimensional monophosphate tungsten bronzes (PO2)4(WO3)2m family were grown by chemical vapour transport technique and the high crystalline quality obtained allowed a reinvestigation of the physical and structural properties. Resistivity measurements revealed three anomalies at TC1 = 258 K, TC2 = 245 K and TC3 = 140 K, never observed until now. Parallel X-ray diffraction investigations showed a specific signature associated with three structural transitions, i.e. the appearance of different sets of satellite reflections below TC1, TC2 and TC3. Several harmonics of intense satellite reflections were observed, reflecting the non-sinusoidal nature of the structural modulations and a strong electron–phonon coupling in the material. These transitions could be associated with the formation of three successive unconventional charge density wave states.

Efficient infiltration of a mesoporous titania matrix with conducting organic polymers or small molecules is one key challenge to overcome for hybrid photovoltaic devices. A quantitative analysis of the backfilling efficiency with time-of-flight grazing incidence small-angle neutron scattering (ToF-GISANS) and scanning electron microscopy (SEM) measurements is presented. Differences in the morphology due to the backfilling of mesoporous titania thin films are compared for the macromolecule poly[4,8-bis­(5-(2-ethyl­hexyl)­thio­phen-2-yl)benzo[1,2-b;4,5-b']di­thio­phene-2,6-diyl-alt-(4-(2-ethyl­hexyl)-3-fluoro­thieno[3,4-b]thio­phene-)-2-carboxyl­ate-2-6-diyl)] (PTB7-Th) and the heavy-element containing small molecule 2-pinacol­boronate-3-phenyl­phen­anthro[9,10-b]telluro­phene (PhenTe-BPinPh). Hence, a 1.7 times higher backfilling efficiency of almost 70% is achieved for the small molecule PhenTe-BPinPh compared with the polymer PTB7-Th despite sharing the same volumetric mass density. The precise characterization of structural changes due to backfilling reveals that the volumetric density of backfilled materials plays a minor role in obtaining good backfilling efficiencies and interfaces with large surface contact.

X-ray diffraction studies of crystals under pressure and quantitative experimental charge density analysis are among the most demanding types of crystallographic research. A successful feasibility study of the electron density in the mineral grossular under 1 GPa pressure conducted at the CRISTAL beamline at the SOLEIL synchrotron is presented in this work. A single crystal was placed in a diamond anvil cell, but owing to its special design (wide opening angle), short synchrotron wavelength and the high symmetry of the crystal, data with high completeness and high resolution were collected. This allowed refinement of a full multipole model of experimental electron distribution. Results are consistent with the benchmark measurement conducted without a diamond-anvil cell and also with the literature describing investigations of similar structures. Results of theoretical calculations of electron density distribution on the basis of dynamic structure factors mimic experimental findings very well. Such studies allow for laboratory simulations of processes which take place in the Earth's mantle.

Noncrystallographic symmetry (NCS) averaging following molecular-replacement phasing is generally the major technique used to solve a structure with several molecules in one asymmetric unit, such as a spherical icosahedral viral particle. As an alternative method to NCS averaging, a new approach to optimize or to refine the electron density directly under NCS constraints is proposed. This method has the same effect as the conventional NCS-averaging method but does not include the process of Fourier synthesis to generate the electron density from amplitudes and the corresponding phases. It has great merit for the solution of structures with limited data that are either twinned or incomplete at low resolution. This method was applied to the case of the T = 1 shell-domain subviral particle of Penaeus vannamei nodavirus with data affected by twinning using the REFMAC5 refinement software.

Crystallographic textures, as they develop for example during cold forming, can have a significant influence on the mechanical properties of metals, such as plastic anisotropy. Textures are typically characterized by a non-uniform distribution of crystallographic orientations that can be measured by diffraction experiments like electron backscatter diffraction (EBSD). Such experimental data usually contain a large number of data points, which must be significantly reduced to be used for numerical modeling. However, the challenge in such data reduction is to preserve the important characteristics of the experimental data, while reducing the volume and preserving the computational efficiency of the numerical model. For example, in micromechanical modeling, representative volume elements (RVEs) of the real microstructure are generated and the mechanical properties of these RVEs are studied by the crystal plasticity finite element method. In this work, a new method is developed for extracting a reduced set of orientations from EBSD data containing a large number of orientations. This approach is based on the established integer approximation method and it minimizes its shortcomings. Furthermore, the L1 norm is applied as an error function; this is commonly used in texture analysis for quantitative assessment of the degree of approximation and can be used to control the convergence behavior. The method is tested on four experimental data sets to demonstrate its capabilities. This new method for the purposeful reduction of a set of orientations into equally weighted orientations is not only suitable for numerical simulation but also shows improvement in results in comparison with other available methods.

Experimental electron-density studies based on high-resolution diffraction experiments allow halogen bonds between heavy halogens to be classified. The topological properties of the electron density in Cl⋯Cl contacts vary smoothly as a function of the inter­action distance. The situation is less straightforward for halogen bonds between iodine and small electronegative nucleophiles, such as nitro­gen or oxygen, where the electron density in the bond critical point does not simply increase for shorter distances. The number of successful charge–density studies involving iodine is small, but at least individual examples for three cases have been observed. (a) Very short halogen bonds between electron-rich nucleophiles and heavy halogen atoms resemble three-centre–four-electron bonds, with a rather symmetric heavy halogen and without an appreciable σ hole. (b) For a narrow inter­mediate range of halogen bonds, the asymmetric electronic situation for the heavy halogen with a pronounced σ hole leads to rather low electron density in the (3,−1) critical point of the halogen bond; the properties of this bond critical point cannot fully describe the nature of the associated inter­action. (c) For longer and presumably weaker contacts, the electron density in the halogen bond critical point is only to a minor extent reduced by the presence of the σ hole and hence may be higher than in the aforementioned case. In addition to the electron density and its derived properties, the halogen–carbon bond distance opposite to the σ hole and the Raman frequency for the associated vibration emerge as alternative criteria to gauge the halogen-bond strength. We find exceptionally long C—I distances for tetra­fluoro­diiodo­benzene molecules in cocrystals with short halogen bonds and a significant red shift for their Raman vibrations.

Density in the urban environment can encompass a multitude of factors such as population or dwelling density or the density of green areas. A new study surveyed professionals regarding how decisions on urban density are made, and has revealed that many feel that developers make most of these decisions, but that local authority planners should have more influence.

A new combination of three models has explored the future dynamics of European livestock distribution. The results indicate that, without environmental policy, livestock density will increase both inside and outside current livestock hotspots. This will also occur to a certain degree with regulation, but the risk of negative impacts will be less likely.

The increased density of forests has been responsible for substantially increasing sequestered carbon in Europe and North America over the past 20 years, according to a recent study. The researchers suggest that managing forests for increased density offers one means of increasing carbon stocks.

Transport infrastructure and urban sprawl are increasingly dividing up landscapes in Europe, threatening wildlife. A new report has quantified landscape fragmentation across 28 European countries. To prevent further negative environmental impacts, it recommends protecting unfragmented areas, monitoring fragmentation and applying fragmentation analysis in planning.

It has always been about being noticed. People dress well or do something bizarre in order to be noticed or make a statement. To get ahead in life or business one needs to be at the top, first in line.

N+1 platform features 8 and 12 port fiber cassettes and leading 96 port density per rack unit

A 4-year-old Douglas-fir plantation in the western Washington Cascades was monitored for 8 years after fertilization with potassium (K), nitrogen (N), and K+N to determine fertilizer effects on rates of mortality from laminated root rot (LRR) and other causes relative to a nonfertilized control.

Can management of 40- to 80-year-old forests on the Olympic Peninsula accelerate the development of stand structures and plant and animal communities associated with much older forests?

Over half (56 percent) of America's forests are privately owned and managed and provide a vast array of public goods and services, such as clean water, timber, wildlife habitat, and recreational opportunities. These important public benefits are being affected by increased housing density in urban as well as rural areas across the country.

This study's objective was to document and describe the current seedling bank of Sitka spruce (Picea sitchensis (Bong.) Carr.) and western hemlock (Tsuga heterophylla (Raf.) Sarg.) stands in southeast Alaska that were partially cut between 1900 and 1984.

In this paper we consider the "quasidensity" of a subset of the product of a Banach space and its dual, and give a connection between quasidense sets and sets of "type (NI)". We discuss "coincidence sets" of certain convex functions and prove two sum theorems for coincidence sets. We obtain new results on the Fitzpatrick extension of a closed quasidense monotone multifunction. The analysis in this paper is self-contained, and independent of previous work on "Banach SN spaces". This version differs from the previous version because it is shown that the (well known) equivalence of quasidensity and "type (NI)" for maximally monotone sets is not true without the monotonicity assumption and that the appendix has been moved to the end of Section 10, where it rightfully belongs.

In this paper, we study the regularity criterion of weak solutions to the three-dimensional (3D) MHD equations. It is proved that the solution $(u,b)$ becomes regular provided that one velocity and one current density component of the solution satisfy% egin{equation} u_{3}in L^{frac{30alpha }{7alpha -45}}left( 0,T;L^{alpha ,infty }left( mathbb{R}^{3} ight) ight) ext{ with }frac{45}{7}% leq alpha leq infty , label{eq01} end{equation}% and egin{equation} j_{3}in L^{frac{2eta }{2eta -3}}left( 0,T;L^{eta ,infty }left( mathbb{R}^{3} ight) ight) ext{ with }frac{3}{2}leq eta leq infty , label{eq02} end{equation}% which generalize some known results.

A molding composition formulation includes a thermoset cross-linkable 12 to 45 micron polymeric resin. Hollow glass microspheroids are present from 2 to 12 total weight percent. An article formed from such a composition is further strengthened by the addition of a surface activating agent bonded to the surface of the glass microspheroids. Conventional particulate fillers when added to an inventive formulation provide enhanced performance when the filler particle has a size sufficiently small to insert within adjacent microspheroid interstitial voids. An unsaturated polyester resin so formed is particularly well suited for the formation of sheet molding compound formulations.

The disclosed technology is related to adjusting an integrated circuit design while accounting for a local density of the design. In particular exemplary embodiments, a local density value for a layout design that defines a plurality of geometric shapes is derived. Subsequently, one or more of the geometric shapes are adjusted such that the local density value is preserved. With some implementations, the local density value is preserved if the adjusted local density value is within a threshold amount of the derived local density value.

In one embodiment an enclosure for a high-density storage system, comprises a backplane to which a plurality of data storage devices may be coupled, a front panel opposite the backplane and defining a first airflow channel adjacent a front side of the data storage devices, a back panel opposite the front panel and comprising a second airflow channel adjacent the backplane, a floor panel and a top panel, a first side panel comprising an array of air flow inlets, a second side panel comprising at least one air flow outlet, and a fan assembly to expel air from the at least one air outlet.

A magnetic recording tape according to one embodiment includes at least about eight data bands, wherein each data band is defined between a pair of adjacent servo tracks, each pair of adjacent servo tracks defining only a single data band therebetween. One of the servo tracks has data encoded therein, the data including data for encryption. A magnetic recording tape according to another embodiment includes a plurality of servo tracks, each servo track comprising a series of magnetically defined bars. An average height of the bars is less than about 50 microns. About eight to about twenty six data bands are present on the tape. A tape supply cartridge according to various embodiments has a magnetic recording tape as described herein.

A machined ceramic article having an initial surface defect density and an initial surface roughness is provided. The machined ceramic article is heated to a temperature range between about 1000° C. and about 1800° C. at a ramping rate of about 0.1° C. per minute to about 20° C. per minute. The machined ceramic article is heat-treated in air atmosphere. The machined ceramic article is heat treated at one or more temperatures within the temperature range for a duration of up to about 24 hours. The machined ceramic article is then cooled at the ramping rate, wherein after the heat treatment the machined ceramic article has a reduced surface defect density and a reduced surface roughness.

A thermoplastic composition that contains a rigid renewable polyester and has a voided structure and low density is provided. To achieve such a structure, the renewable polyester is blended with a polymeric toughening additive to form a precursor material in which the toughening additive can be dispersed as discrete physical domains within a continuous matrix of the renewable polyester. The precursor material is thereafter stretched or drawn at a temperature below the glass transition temperature of the polyester (i.e., “cold drawn”). This creates a network of voids located adjacent to the discrete domains, which as a result of their proximal location, can form a bridge between the boundaries of the voids and act as internal structural “hinges” that help stabilize the network and increase its ability to dissipate energy. The present inventors have also discovered that the voids can be distributed in a substantially homogeneous fashion throughout the composition.

A storage system for items such as substrate carriers includes at least one stocker including a plurality of storage areas each adapted to store at least one storage device. At least one movable support is arranged on the at least one stocker. A control controls movement of the at least one movable support at least between a first position wherein the at least one movable support receives the at least one storage device outside one of the storage areas and a second position wherein the at least one movable support is arranged substantially within the one of the storage areas.

An apparatus including a die including a dielectric material on a device side, an insulating layer surrounding a die area and embedding a thickness dimension of the die; and a carrier including a plurality of layers of conductive material disposed on the device side of the die, a first one of the layers of conductive materials being formed on the insulating layer and patterned into traces at least a portion of which are connected to respective contact points on the die. A method including disposing a die on a sacrificial substrate with a device side of the die opposite the sacrificial substrate; disposing a mold on the sacrificial substrate around; introducing an insulating material into a chase of the mold; removing the mold; forming a carrier on the insulating material adjacent a device side of a die; and separating the die and the carrier from the sacrificial substrate.

An RF test and measurement device, including a front end for receiving a time-varying signal and a real-time engine for generating digital frequency domain spectrums based on the time-varying signal. The device also includes a memory subsystem containing a frequency domain bitmap which is updated through sequential receipt and storage of the digital frequency domain spectrums. The real time engine is further configured to monitor the frequency domain bitmap for occurrence of a signal characteristic, and in response to detection of the signal characteristic, cause a capture of the time-varying signal into a storage location of the RF test and measurement device.

A device for mixing multiple (N) pulse density modulated (PDM) bit streams of a bit rate, the device comprises an input logic, an error accumulation circuit, an error correction circuit and an adder of more than N bits; wherein the device is arranged to output an output PDM bit stream that represents a mixture of the multiple input PDM bit streams; wherein the output PDM bit stream comprises a plurality of output PDM bits, wherein a certain output PDM bit of a plurality of output PDM bits that form the output PDM bit stream is generated during a certain clock cycle; wherein the input logic is arranged to select, during each fraction of the certain clock cycle, a current bit of a selected PDM bit stream, wherein different PDM bit streams are selected during different fragments of the certain clock cycle; wherein the error accumulation circuit is arranged to store intermediate values during a first fraction till a penultimate fraction of the certain clock signal and to store a last value during a last fraction of the certain clock signal.

The present invention relates to a digital modulation method and a corresponding modulator. The modulator comprises a transcoder (110) followed by a FIFO register (120) and a 2-PSK modulator (130). The transcoder codes a binary word of fixed size into a code word of variable size using a transcoding table. The transcoding table codes at least one first binary word, leading to a first number of phase transitions at the output of the modulator, into a second word of size greater than that of the first word, leading to, at the output of the modulator, a second number of phase transitions less than the first number of phase transitions.

The present invention provides a method for improving operation density of rail vehicles and for preventing head-on collision and rear-ending collision. Said method divides a rail line into equidistant electronic zones, the length of a zone being greater than the shortest safe distance between two running vehicles. Said method installs a locomotive passing detection alarm device in each zone, when a locomotive travels at high speed on the rail, the locomotive passing detection alarm device corresponding to the zone occupied by the locomotive itself will simultaneously access adjacent front and back zones, and determine whether the two adjacent zones are simultaneously occupied by locomotives. If the two adjacent. zones are simultaneously occupied by locomotives, the locomotive passing alarm device will send an alarm signal to the locomotives to warn or otherwise take measures. The aforesaid method can avoid locomotive head-on collision and rear-end collision and increase transportation density according to the vehicle speed and distance at the same time, thus improving the transportation efficiency.

A method for reducing the coking time in the oven area near the door or end wall and for improving coke quality and situation of emissions by compensating for radiation losses through coke oven chamber doors and end walls is described. This compensation is accomplished by varying the height of the coal cake in the environment of the frontal coke oven chamber doors. The variation is achieved both by increasing or decreasing the coal cake over part of the length or over the entire length of the coke oven chamber door. The reduction in the height of the coal cake can be generated by omission of coal or coal compacts, the increase in height can be accomplished by stacking of coal and pressing or adding of coal compacts, with it also being envisaged to omit the pressing cycle so as to obtain a recess with a lower coal cake density which also has less heat radiation.

The present invention is directed to an explosive composition comprised of heavy ANFO and expanded polymeric beads that have a density that is less than the density of the heavy ANFO. The expanded polymeric beads have a size that is determined or based on the size of ammonium nitrate prills used in the heavy ANFO portion of the composition. In one embodiment, the expanded polymeric beads that are utilized in the composition are at least 70% of the lower limit of the mesh size of the predominant ammonium nitrate prill mesh size. In another embodiment, the expanded polymeric beads are at least 70% of the a size that is related to the average mesh size of the ammonium nitrate prills.

A semiconductor device has a plurality of semiconductor die. A first prefabricated insulating film is disposed over the semiconductor die. A conductive layer is formed over the first prefabricated insulating film. An interconnect structure is formed over the semiconductor die and first prefabricated insulating film. The first prefabricated insulating film is laminated over the semiconductor die. The first prefabricated insulating film includes glass cloth, glass fiber, or glass fillers. The semiconductor die is embedded within the first prefabricated insulating film with the first prefabricated insulating film covering first and side surfaces of the semiconductor die. The interconnect structure is formed over a second surface of the semiconductor die opposite the first surface. A portion of the first prefabricated insulating film is removed after disposing the first prefabricated insulating film over the semiconductor die. A second prefabricated insulating film is disposed over the first prefabricated insulating film.