Psycho-Physical Analysis of the Betts Visual Acuity Test

Although visual acuity is of chief concern to the optometrist from the professional standpoint, the physicist should be no less concerned from the standpoint of its applications to work in optics and illumination. Visual acuity is indeed difficult to measure and many types of acuity tests have been devised. The Clason acuity meter and the Snellen chart are the accepted standards used by optometrists. Another test for measuring acuity, which is administered on the stereoscope, is one of many visual tests that has been developed by Betts, Director of Teacher Education, State Normal School, Oswego, N. Y., who worked jointly with the Keystone View Company of Meadville, Penna

Visual Acuity Measurements with the Betts Test Cards

Three commonly accepted notations for visual acuity are: (1) the Snellen System, which follows an arithmetic progression, (2) the Clason Decimal System, which bears a constant relationship to the Snellen System, and (3) the Snell and Sterling System, which follows a geometrical progression and is commonly referred to as the system of the American Medical Association. Visual acuity is indeed difficult to measure and many types of acuity tests have been devised. One such test, which is administered on the stereoscope, has been devised by Betts, Director of Teacher Education, State Normal School, Oswego, N. Y., who worked jointly with the Keystone View Company of Meadville, Penn. The principle of the Betts tests is the ability to resolve a black clot set within a target when placed in the stereoscope. In tests that were made the Betts acuity test was given simultaneously with the standard Clason acuity tests and curves were plotted showing the relationship between the two. Measurements were made on 5000 persons in connection with automobile drivers\u27 tests given in several states

Generalized Relax-and-Fix heuristic

This paper introduces a heuristic for mixed-integer mathematical programs, that can be seen as a generalization of the relax-and-fix heuristic: a sequence of derived subproblems is solved, progressively fixing variables in the original problem. We propose a generic implementation and report on numerical results for four well-known operational research applications: lot-sizing, vehicle routing, bin-packing and portfolio optimization. Results show that this heuristic may be competitive depending on the definition of subproblems

Flow injection of liquid samples to a mass spectrometer with ionization under vacuum conditions: a combined ion source for single-photon and electron impact ionization

Electrospray ionization (ESI), atmospheric pressure chemical ionization (APCI), and atmospheric pressure photo-ionization (APPI) are the most important techniques for the ionization of liquid samples. However, working under atmospheric pressure conditions, all these techniques involve some chemical rather than purely physical processes, and therefore, side reactions often yield to matrix-dependent ionization efficiencies. Here, a system is presented that combines both soft single-photon ionization (SPI) and hard 70 eV electron impact ionization (EI) of dissolved compounds under vacuum conditions. A quadrupole mass spectrometer was modified to enable direct EI, a technique developed by Cappiello et al. to obtain library-searchable EI mass spectra as well as soft SPI mass spectra of sample solutions. An electron beam-pumped rare gas excimer lamp working at 126 nm was used as well as a focusable vacuum UV light source for single-photon ionization. Both techniques, EI and SPI, were applied successfully for flow injection experiments providing library-matchable EI fragment mass spectra and soft SPI mass spectra, showing dominant signals for the molecular ion. Four model compounds were analyzed: hexadecane, propofol, chlorpropham, and eugenol, with detection limits in the picomolar range. This novel combination of EI and SPI promises great analytical benefits, thanks to the possibility of combining database alignment for EI data and molecular mass information provided by SPI. Possible applications for the presented ionization technology system are a matrix-effect-free detection and a rapid screening of different complex mixtures without time-consuming sample preparation or separation techniques (e.g., for analysis of reaction solutions in combinatorial chemistry) or a switchable hard (EI) and soft (SPI) MS method as detection step for liquid chromatography

Resolving coffee roasting-degree phases based on the analysis of volatile compounds in the roasting off-gas by Photoionization Time-of-Flight Mass Spectrometry (PI-TOFMS) and statistical data analysis: Toward a PI-TOFMS roasting model.

Coffee beans of two cultivars, Arabica (Mexico) and Robusta (Vietnam), were roasted in a small-scale drum roaster at different temperature profiles. Evolving volatile compounds out of the roasting off-gas were analyzed by photoionization mass spectrometry at four different wavelengths, either with single-photon ionization (SPI) or resonance-enhanced multiphoton ionization (REMPI). The different analyte selectivities at the four wavelengths and their relevance for the examination of the roasting process were discussed. Furthermore, intensities of observed m/z were grouped by non-negative matrix factorization (NMF) to reveal the temporal evolutions of four roasting phases ("evaporation", "early roast", "late roast", and "overroast") from NMF scores and the corresponding molecular composition from the NMF factor loadings, giving chemically sound results concerning the roasting phases. Finally, linear classifiers were constructed from real mass spectra at maximum NMF scores by linear discriminant analysis to obtain quantities which are simple to measure for real-time analysis of the roasting process

The physiological polyphosphate as a healing biomaterial for chronic wounds: Crucial roles of its antibacterial and unique metabolic energy supplying properties

Insufficient metabolic energy, in the form of adenosine triphosphate (ATP), and bacterial infections are among the main causes for the development of chronic wounds. Previously we showed that the physiological inorganic polymer polyphosphate (polyP) massively accelerates wound healing both in animals (diabetic mice) and, when incorporated into mats, in patients with chronic wounds. Here, we focused on a hydrogel-based gel formulation, supplemented with both soluble sodium polyP (Na-polyP) and amorphous calcium polyP nanoparticles (Ca-polyP-NP). Exposure of human epidermal keratinocytes to the gel caused a significant increase in extracellular ATP level, an effect that was even enhanced when Na-polyP was combined with Ca-polyP-NP. Furthermore, it is shown that the added polyP in the gel is converted into a coacervate, leading to encapsulation and killing of bacteria. The data on human chronic wounds showed that the administration of hydrogel leads to the complete closure of these wounds. Histological analysis of biopsies showed an increased granulation of the wounds and an enhanced microvessel formation. The results indicate that the polyP hydrogel, due to its properties to entrap bacteria and generate metabolic energy, is a very promising formulation for a new therapy for chronic wounds

Acceleration of Wound Healing through Amorphous Calcium Carbonate, Stabilized with High-Energy Polyphosphate

Amorphous calcium carbonate (ACC), precipitated in the presence of inorganic polyphosphate (polyP), has shown promise as a material for bone regeneration due to its morphogenetic and metabolic energy (ATP)-delivering properties. The latter activity of the polyP-stabilized ACC (“ACC∙PP”) particles is associated with the enzymatic degradation of polyP, resulting in the transformation of ACC into crystalline polymorphs. In a novel approach, stimulated by these results, it was examined whether “ACC∙PP” also promotes the healing of skin injuries, especially chronic wounds. In in vitro experiments, “ACC∙PP” significantly stimulated the migration of endothelial cells, both in tube formation and scratch assays (by 2- to 3-fold). Support came from ex vivo experiments showing increased cell outgrowth in human skin explants. The transformation of ACC into insoluble calcite was suppressed by protein/serum being present in wound fluid. The results were confirmed in vivo in studies on normal (C57BL/6) and diabetic (db/db) mice. Topical administration of “ACC∙PP” significantly accelerated the rate of re-epithelialization, particularly in delayed healing wounds in diabetic mice (day 7: 1.5-fold; and day 13: 1.9-fold), in parallel with increased formation/maturation of granulation tissue. The results suggest that administration of “ACC∙PP” opens a new strategy to improve ATP-dependent wound healing, particularly in chronic wounds

Acceleration of Wound Healing through Amorphous Calcium Carbonate, Stabilized with High-Energy Polyphosphate

Amorphous calcium carbonate (ACC), precipitated in the presence of inorganic polyphosphate (polyP), has shown promise as a material for bone regeneration due to its morphogenetic and metabolic energy (ATP)-delivering properties. The latter activity of the polyP-stabilized ACC (“ACC∙PP”) particles is associated with the enzymatic degradation of polyP, resulting in the transformation of ACC into crystalline polymorphs. In a novel approach, stimulated by these results, it was examined whether “ACC∙PP” also promotes the healing of skin injuries, especially chronic wounds. In in vitro experiments, “ACC∙PP” significantly stimulated the migration of endothelial cells, both in tube formation and scratch assays (by 2- to 3-fold). Support came from ex vivo experiments showing increased cell outgrowth in human skin explants. The transformation of ACC into insoluble calcite was suppressed by protein/serum being present in wound fluid. The results were confirmed in vivo in studies on normal (C57BL/6) and diabetic (db/db) mice. Topical administration of “ACC∙PP” significantly accelerated the rate of re-epithelialization, particularly in delayed healing wounds in diabetic mice (day 7: 1.5-fold; and day 13: 1.9-fold), in parallel with increased formation/maturation of granulation tissue. The results suggest that administration of “ACC∙PP” opens a new strategy to improve ATP-dependent wound healing, particularly in chronic wounds