41 research outputs found
Application of Laser Mass Spectrometry to Art and Archaeology
REMPI laser mass spectrometry is a combination of resonance enhanced multiphoton ionization spectroscopy and time of flight mass spectrometry, This technique enables the collection of mass specific optical spectra as well as of optically selected mass spectra. Analytes are jet-cooled by entrainment in a molecular beam, and this low temperature gas phase analysis has the benefit of excellent vibronic resolution. Utilizing this method, mass spectrometric analysis of historically relevant samples can be simplified and improved; Optical selection of targets eliminates the need for chromatography while knowledge of a target's gas phase spectroscopy allows for facile differentiation of molecules that are in the aqueous phase considered spectroscopically indistinguishable. These two factors allow smaller sample sizes than commercial MS instruments, which in turn will require less damage to objects of antiquity. We have explored methods to optimize REMPI laser mass spectrometry as an analytical tool to archaeology using theobromine and caffeine as molecular markers in Mesoamerican pottery, and are expanding this approach to the field of art to examine laccaic acid in shellacs
Direct Analysis of Xanthine Stimulants in Archaeological Vessels by Laser Desorption Resonance Enhanced Multiphoton Ionization
Perceptual Load-Dependent Neural Correlates of Distractor Interference Inhibition
The load theory of selective attention hypothesizes that distractor interference is suppressed after perceptual processing (i.e., in the later stage of central processing) at low perceptual load of the central task, but in the early stage of perceptual processing at high perceptual load. Consistently, studies on the neural correlates of attention have found a smaller distractor-related activation in the sensory cortex at high relative to low perceptual load. However, it is not clear whether the distractor-related activation in brain regions linked to later stages of central processing (e.g., in the frontostriatal circuits) is also smaller at high rather than low perceptual load, as might be predicted based on the load theory.We studied 24 healthy participants using functional magnetic resonance imaging (fMRI) during a visual target identification task with two perceptual loads (low vs. high). Participants showed distractor-related increases in activation in the midbrain, striatum, occipital and medial and lateral prefrontal cortices at low load, but distractor-related decreases in activation in the midbrain ventral tegmental area and substantia nigra (VTA/SN), striatum, thalamus, and extensive sensory cortices at high load.Multiple levels of central processing involving midbrain and frontostriatal circuits participate in suppressing distractor interference at either low or high perceptual load. For suppressing distractor interference, the processing of sensory inputs in both early and late stages of central processing are enhanced at low load but inhibited at high load
Shakespeare's plays with his life : illustrated with many hundred wood-cuts, executed by H.W. Hewet, after designs by Kenny Meadows, Harvey, and others /
The text is based on Collier's; the notes, etc., selected from Malone, Singer, Collier, and especially from Knight's pictorial edition, from which most of the illustrations are taken.each separately paged, without continuous pagination.Issued in parts, most with wrappers having title: Harper's illuminated and illustrated Shakespeare. The fascicles, though numbered, were not intended to be bound in numerical order. The order prescribed by the publisher and printed in the table of contents (v. 1. p. [iii]) is that followed in the LC copy; Verplanck, however, urged (v. 1, p. xiii subscribers to arrange the plays--within the three groups, Comedies, Histories, and Tragedies--in the order of their composition. To this end, the plays areEach volume has added, engraved, t.-p.: The illustrated Shakespeare ...The first American illustrated Shakespeare. Complete sets of this, the only printing, are scarce due to destruction of the plates in Harper's 1853 fire. Cf. Westfall.v. 1: Preface. Order of the play. William Shakespeare, a biography. Some account of the life of William Shakespeare / by Mr. Rowe. Life of William Shakespeare / abridged from Collier. Shakespeare's will. Folio editions of Shakespeare's plays. Commendatory verses.Shakespeare's name and autographs. King John. King Richard II. King Henry IV, part 1. King Henry IV, part 2. Henry V. King Henry VI, part 1. King Henry VI, part 2. King Henry VI, part 3. King Richard III. King Henry VIII -- v. 2: Two gentlemen of Verona. Comedy of errors. Taming of the shrew. Much ado about nothing. Love labour's lost. Merchant of Venice. Merry wives of Windsor. Twelfth night. As you like it. Midsummer night's dream. Measure for measure. Tempest. All's well that ends well. Winter's tale -- v. 3: Romeo and Juliet. Othello. Hamlet. Macbeth. King Lear. Cymbeline. Timon of Athens. Coriolanus. Julius Caesar. Anthony and Cleopatra. Troilus and Cressida. Titus Andronicus. Pericles.Jaggard, W. Shakespeare bibl.,Mode of access: Internet.spec: Inscribed on title-page: Presented to E. H. Thompson [sic.], Esq. by G.C. Verplanck, New York, Oct. 1849." Bound in brown half-calf with gilt design and lettering on spine. Marbled boards, fore-edges, and end-papers
Probing The Mechanism Of Insulin Aggregation With Added Metalloporphyrins
The mechanism of inhibition of insulin-based amyloid gel formation by metal derivatives of tetrakis(4-sulfonatophenyl)porphyrin has been investigated. Time-course UV/vis measurements in conjunction with atomic force microscopy (AFM) were used to study the correlation between observed kinetics and amyloid structure for various concentration ranges of added metalloporphyrins. Observed structures include fibrils as well as circular, ring-like structures formed as a result of the interaction of insulin with porphyrin. In addition, binding studies demonstrate that the effectiveness of inhibition of the various metalloporphyrins is directly related to the strength of binding to insulin. It is suggested that both the electron distribution in the porphyrin core and the tendency to form porphyrin dimers affect both the structure of amyloid formed and the kinetic profile of the reaction
Driver stress A literature review
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