Dark costs, missing data: shedding some light on services trade

A structural gravity model is used to estimate barriers to services trade across many sectors, countries and time. Since the disaggregated output data needed to flexibly infer border barriers are often missing for services, we derive a novel methodology for projecting output data. The empirical implementation sheds light on the role of institutions, geography, size and digital infrastructure as determinants of border barriers. We find that border barriers have generally fallen over time but there are differences across sectors and countries. Notably, border effects for the smallest economies have remained stable, giving rise to a divergent pattern across countries

Assessing blood brain barrier dynamics or identifying or measuring selected substances, including ethanol or toxins, in a subject by analyzing Raman spectrum signals

A non-invasive method for analyzing the blood-brain barrier includes obtaining a Raman spectrum of a selected portion of the eye and monitoring the Raman spectrum to ascertain a change to the dynamics of the blood brain barrier.Also, non-invasive methods for determining the brain or blood level of an analyte of interest, such as glucose, drugs, alcohol, poisons, and the like, comprises: generating an excitation laser beam at a selected wavelength (e.g., at a wavelength of about 400 to 900 nanometers); focusing the excitation laser beam into the anterior chamber of an eye of the subject so that aqueous humor, vitreous humor, or one or more conjunctiva vessels in the eye is illuminated; detecting (preferably confocally detecting) a Raman spectrum from the illuminated portion of the eye; and then determining the blood level or brain level (intracranial or cerebral spinal fluid level) of an analyte of interest for the subject from the Raman spectrum. In certain embodiments, the detecting step may be followed by the step of subtracting a confounding fluorescence spectrum from the Raman spectrum to produce a difference spectrum; and determining the blood level and/or brain level of the analyte of interest for the subject from that difference spectrum, preferably using linear or nonlinear multivariate analysis such as partial least squares analysis. Apparatus for carrying out the foregoing methods are also disclosed

Non-invasive method of measuring cerebral spinal fluid pressure

The invention provides a method of non-invasively determining intracranial pressure from measurements of an eye. A parameter of an optic nerve of the eye is determined, along with an intraocular pressure of the eye. The intracranial pressure may be determined from the intraocular pressure and the parameter

Non-invasive glucose monitor

A non-invasive method for determining blood level of an analyte of interest, such as glucose, comprises: generating an excitation laser beam (e.g., at a wavelength of 700 to 900 nanometers); focusing the excitation laser beam into the anterior chamber of an eye of the subject so that aqueous humor in the anterior chamber is illuminated; detecting (preferably confocally detecting) a Raman spectrum from the illuminated aqueous humor; and then determining the blood glucose level (or the level of another analyte of interest) for the subject from the Raman spectrum. Preferably, the detecting step is followed by the step of subtracting a confounding fluorescence spectrum from the Raman spectrum to produce a difference spectrum; and determining the blood level of the analyte of interest for the subject from that difference spectrum, preferably using linear or nonlinear multivariate analysis such as partial least squares analysis. Apparatus for carrying out the foregoing method is also disclosed

On the minimization of contact resistance in organic thin-film transistors

Organic semiconductors have been implemented in a variety of electronic devices ranging from organic light-emitting diodes, organic photovoltaic devices, and organic transistors. In all of these devices, the efficient injection and/or extraction of charges across interfaces with conducting contacts is an essential requirement for device performance. The high contact resistance in organic transistors, which limits their usefulness in high-frequency electronics applications, has been a particularly challenging problem to solve. The contact resistance can depend strongly on various parameters, including the transistor architecture and the mismatch between the contact work function and the transport levels of the organic semiconductor. In this work, it is shown that using a thin gate-dielectric layer (around 5 nm) in a thin-film transistor (TFT) in combination with contacts modified using a chemisorbed monolayer to tune the contact-semiconductor interface properties yields record-low contact resistance in organic transistors (as small as 10 Ωcm). This approach was then extended to small-scale TFTs and circuits leading to additional record results in the dynamic performance, including voltage-normalized transit frequency of 7 MHz/V. Finally, strong evidence is shown that Fermi-level pinning limits the effectiveness of tuning the contact work function with chemisorbed monolayers to improve the contact resistance further

Critical Evaluation of Organic Thin-Film Transistor Models

Thin-film transistors (TFTs) represent a wide-spread tool to determine the charge-carrier mobility of materials. Mobilities and further transistor parameters like contact resistances are commonly extracted from the electrical characteristics. However, the trust in such extracted parameters is limited, because their values depend on the extraction technique and on the underlying transistor model. We propose a technique to establish whether a chosen model is adequate to represent the transistor operation. This two-step technique analyzes the electrical measurements of a series of TFTs with different channel lengths. The first step extracts the parameters for each individual transistor by fitting the full output and transfer characteristics to the transistor model. The second step checks whether the channel-length dependence of the extracted parameters is consistent with the model. We demonstrate the merit of the technique for distinct sets of organic TFTs that differ in the semiconductor, the contacts, and the geometry. Independent of the transistor set, our technique consistently reveals that state-of-the-art transistor models fail to reproduce the correct channel-length dependence. Our technique suggests that contemporary transistor models require improvements in terms of charge-carrier-density dependence of the mobility and/or the consideration of uncompensated charges in the transistor channel.Comment: 20 pages, 10 figure

Recent Population Change in the United States.

Twenty-six computer-generated maps document changes in the U. S. population growth rate from 1950 to 1975. Data on population change, net migration, natural increase, and per capita income are presented on a county-by-county basis

What can the activation energy tell about the energetics at grain boundaries in polycrystalline organic films?

Charge-carrier transport at the semiconductor-gate dielectric interface in organic field-effect transistors is critically dependent on the degree of disorder in the typically semi-crystalline semiconductor layer. Charge trapping can occur at the interface as well as in the current-carrying semiconductor layer itself. A detailed and systematic understanding of the role of grain boundaries between crystallites and how to avoid their potentially detrimental effects is still an important focus of research in the organic electronics community. A typical macroscopic measurement technique to extract information about the energetics of the grain boundaries is an activation energy measurement. Here, we compare detailed experiments on the energetic properties of monolayer thin films implemented in organic field-effect transistors, having controlled numbers of grain boundaries within the channel region to kinetic Monte-Carlo simulations of charge-carrier transport to elucidate the influence of grain boundaries on the extracted activation energies. Two important findings are: 1) whereas the energy at the grain boundary does not change with the number of grain boundaries in a thin film, both the measured and simulated activation energy increases with the number of grain boundaries. 2) In simulations where both energy barriers and valleys are present at the grain boundaries there is no systematic relation between the number of grain boundaries and extracted activation energies. We conclude, that a macroscopic measurement of the activation energy can serve as general quality indicator of the thin film, but does not allow microscopic conclusions about the energy landscape of the thin film