bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigation of Fosfomycin Resistance and Plasmid-mediated Fosfomycin Resistance Genes in Enterobacterales Isolates
Authors: Ulker Kubra , Cayci Yeliz , Birinci Asuman
Published: March 2024

The study aimed to investigate the fosfomycin resistance in Enterobacterales isolates and the presence of plasmid-mediated fosfomycin resistance genes fosA3 and fosC2 in fosfomycin-resistant Enterobacterales isolates. A total of 2095 Enterobacterales isolates obtained from urine samples were included in the study. Identification of isolates was performed in the Vitek MS. The antimicrobial susceptibility of the isolates and detection of ESBL was determined using the Vitek 2 Compact. In 185 fosfomycin-resistant isolates, fosA3 and fosC2 genes were investigated by PCR. In addition, carbapenemase genes were investigated in carbapenem-resistant isolates. In 2095 Enterobacterales, 65.8% of the isolates were E. coli, and fosfomycin resistance was determined as 22%. ESBL production was defined as 36.5%, 58.1%, and 32.5% in all isolates, K. pneumoniae, and E. coli isolates, respectively. K. pneumoniae (56.2%) were the most frequently isolated bacteria among 185 fosfomycin-resistant Enterobacterales isolates. In these isolates, 66.95% were ESBL-producing Enterobacterales, and 35.7% were carbapenem-resistant isolates. According to the PCR results, two of the 185 Enterobacterales isolates were positive for the fosA3 gene, fosC2 gene was not detected. According to PCR for carbapenemase genes results with these isolates, blaOXA–48 positivity was 66.7%, and blaNDM positivity was 3%. blaKPC and blaVIM positivity could not be detected. In our study, the prevalence of fosA3 was 1.1%. The occurrence of fosA3 gene positivity in Enterobacterales isolates is important for the future treatment of UTIs.
Thymoquinone Ameliorates Chemotherapy-induced Cognitive Impairment (Chemobrain) by Inhibiting Oxidative Stress, Inflammatory Response in the Brain of Rat
Authors: Akcay Guven , Mercan Tanju , Ozdemir Semir , Derin Narin
Published: March 2024

The aim of this study was to investigate the therapeutic efficacy of antioxidant thymoquinone (TQ) treatment on neuroinflammation against the negative effects of Doxorubicin (DOX) used in cancer treatment on learning and memory by behavioural and molecular mechanisms. Forty male Wistar rats were divided into four groups: Control, DOX, TQ and DOX+TQ. DOX and DOX+TQ groups were injected with 3 mg/kg (i.p.) DOX for 4 weeks. TQ and DOX+TQ groups received 10 mg/kg TQ by gavage. Learning, locomotor activity, oxidative stress and inflammatory levels were evaluated. In behavioural experiments data, a significant decrease was observed in DOX group compared to Control group, while a significant increase was observed in DOX+TQ group compared to DOX group. Compared to the control group, TOC, IL-1β, IL-6 and TNF-α levels increased, while TAC level decreased in the DOX group. With TQ treatment, a significant decrease was observed in TOC, IL-1β, IL-6 and TNF-α levels in the TQ and DOX+TQ groups compared to the DOX group, while significant increases were observed in TAC level. In our study, DOX toxicity increased oxidative stress and neuroinflammation and caused learning and memory loss, while TQ decreased oxidative stress and neuroinflammation and improved learning and memory disorders.
Lateral Sinus Floor Elevation in Cases of an Intact and Perforated Schneiderian Membrane
Authors: Fakih Khodor , Edreva Mariya , Stoichkov Biser , Fakih Yana
Published: March 2024

The study comprised 20 lateral sinus floor elevation cases performed in 18 patients. During surgery, in four cases, a perforation of the Schneiderian membrane was detected. An attempt to suture the perforated membrane may increase the risk of enlarging the perforation. Therefore, we suggest a more conservative protocol be applied in all four cases where perforation occurred. The procedure consists of the 3-layer technique: an absorbable oxidized cellulose gauze moisturized with Dicynone was placed in this area. Under it, as a second layer, a PRF membrane is applied and then covered with a slow-resorbable collagen membrane. At that point, the surgery continues with the placement of the bone substitute material, and the sinus-lifting is finalized according to the selected protocol.

The clinical studies demonstrate that the bone graft has a slower healing rate in areas with perforation, which is a proof of the osteogenic properties of the Schneiderian membrane. The cases described reveal that using this surgical protocol is risk-free and has a high success rate.
Competence as an element of “mediation readiness”
Authors: Beck Connie J. A. , Frost Lynda E.
Published: January 2008

This article introduces a specific standard to the mediation community with the idea of sparking debate that would lead to a commonly accepted standard for competence to participate in mediation for divorce. It delineates the broad contours of an assessment process using the proposed standard and examines practical implications and next steps for mediators related to the establishment of a common standard. It then describes how the proposed standard could be incorporated in mediation trainings, model rules, and state statutes and regulations, leading to more uniform and equitable decisions and increasing the pro‐cedural fairness of divorce mediations within and across jurisdictions.
Sustainable industrial development and environment protection: An emerging perspective
Authors: Goyal S.K. , Nema P. , Devotta S.
Published: January 2008

A concept of an integrated industrial complex encompassing three major industries; viz. sugar, distillery and paper along with a cogeneration plant (generating electricity and process steam required by the industries in the complex) is presented in this article. Molasses and bagasse generated in the sugar industry are proposed to be used by the distillery and paper industry respectively. Surplus bagasse would be used as fuel in cogeneration plant. Sugar, distillery, and paper industries generate high strength wastewater in large volume, which when treated anaerobically produces biogas. This scheme would provide twin advantages of pollution load reduction at low cost coupled with energy production, which will also partially meet the energy requirement of the industrial complex. The entailing benefits would be reduction in fuel consumption and lower air emissions. Low strength wastewater from different processes as well as sewage from industries and townships can be treated in a combined wastewater treatment plant. The treated wastewater can be recycled/reused for industrial as well as for irrigation purposes in the complex and/or nearby industries and agricultural land. © 2008 American Institute of Chemical Engineers Environ Prog, 2008
Free second toe one‐stage‐plasty and transfer for thumb or finger reconstruction
Authors: Zhang Jingliang , Xie Zhenrong , Lei Yanwen , Song Jun , Guo Qiaohong , Xiao Junbo
Published: January 2008

Free second toe transfer has become a popular method for the management of thumb or finger reconstruction. However, this creates an obvious appearance defect. A new operating procedure has been used since 1999. To enlarge the perimeter of the reconstructed thumb, a composite tissue strip flap from the fibular of great toe pedicled with the fibular proper plantar digital artery, combined or not with the island dorsal index finger flap, was inlaid with the second toe at the same time before the reconstruction. A crescent double‐winged dorsal metatarsus flap, connected with second toe, in combination with the partial metatarsal bone, was also used to reconstruct fingers. There were 36 patients in the study group with a follow‐up time of 6 months to 3 years. The thumb and finger reconstructed in this way showed better appearance, with normal caliber and length and without obvious adverse affects. This method has ameliorated the embarrassing appearance of the reconstructed thumb with earlier methods and is a relatively ideal method for thumb or finger reconstruction. © 2008 Wiley‐Liss, Inc. Microsurgery, 2008.
The plastid sigma factor SIG5 is involved in the diurnal regulation of the chloroplast gene psbD in the moss Physcomitrella patens
Authors: Ichikawa Kazuhiro , Shimizu Akane , Okada Ryo , Satbhai Santosh Balasaheb , Aoki Setsuyuki
Published: January 2008

We analyzed the function of a plastid sigma factor, SIG5, by targeted gene disruption in the moss Physcomitrella patens. High‐intensity light induced the chloroplast gene psbD in the wild‐type strain (WT), whereas this induction was nullified in the PpSig5‐disrupted strains (ΔSig5). Moreover, diurnally regulated changes of psbD transcription showed lowered amplitude in ΔSig5 than in WT. We concluded that the moss SIG5 mediates multiple layers of signals to intricately regulate psbD transcription.
Resonant excitation of the quasi‐decadal oscillation by the 11‐year signal in the Sun's irradiance
Authors: White Warren B. , Liu Zengyu
Published: January 2008

The quasidecadal oscillation (QDO) of 9‐ to 13‐year period in the Earth's climate system has been found governed by a delayed action oscillator (DAO) mechanism in the tropical Pacific Ocean similar to that governing the El Niño–Southern Oscillation (ENSO) of 3‐ to 5‐year period. It also fluctuated in phase with the ∼11‐year‐period signal in the Sun's total irradiance throughout the twentieth century. In earlier attempts to explain this association, a conceptual ocean‐atmosphere coupled model of the DAO mechanism in the tropical Pacific Basin was driven by 11‐year‐period solar forcing, producing a QDO that was in damped resonance with the solar forcing. In the present study, we likewise force a fully coupled ocean‐atmosphere general circulation model (i.e., Fast Ocean‐Atmosphere Model (FOAM)) of Jacob et al. (2001), adding an 11‐year‐period cosine signal of amplitude ∼2.0 W m−2 to the solar constant in the model. In the presence of this 11‐year‐period solar forcing the FOAM simulates both the ENSO and the QDO, while in its absence the FOAM simulates only the ENSO. We find the model QDO governed by a tropical DAO mechanism with patterns and evolution similar to those observed. We find its warm phase lagging peak solar forcing by ∼1–3 years, as observed and consistent with damped‐resonant excitation of the tropical DAO of the QDO by the 11‐year‐period solar forcing in the earlier conceptual model.
Collisional quenching of rotations in lithium dimers by ultracold helium: The Li2(aΣu+3) and Li2+(XΣg+2) targets
Authors: González-Sánchez L. , Bodo E. , Gianturco F. A.
Published: January 2008

Quantum coupled-channel scattering calculations have been carried out at ultralow energies (down to 10−5K) for rotational quenching of ionic and spin-stretched states of the lithium dimer in collision with He atoms. Marked cross section differences, to be related to changes in their interactions with He, have been observed with respect to the singlet case while little changes in the collisional behavior are seen to occur upon ionization when the spin-stretched target is considered. Both effects originate from an interplay of structural and dynamical features of the colliding partners which are analyzed in detail.
Effect of packing parameter on phase diagram of amphiphiles: An off-lattice Gibbs ensemble approach
Authors: Bourov Geuorgui K. , Bhattacharya Aniket
Published: January 2008

We determine the phase diagram of several amphiphilic molecules as a function of the amphiphilic parameter α defined as the ratio of the volume of hydrophilic to hydrophobic segments using the Gibbs ensemble Monte Carlo method supplemented by configurational bias scheme. Specifically, we study amphiphilic molecules h1t7, h2t6, and h3t5, for which α=0.14, 0.33, and 0.60 respectively, and demonstrate that the former two exhibit phase separation while h3t5 forms micelles, supporting the contention that α=0.5 is the border line for phase separation and micellization, as observed in previous lattice Monte Carlo studies [Panagiotopoulos et al., Langmuir 18, 2940 (2002)]. Further, we study the phase separation in amphiphilic molecules as a function of the packing parameter by varying the size of the hydrophilic head for each molecule. We find that a larger hydrophilic head lowers the critical temperature Tc, and raises the critical density ρc.
Magnetization reversal in Co/Pt multilayer with weak intergranular coupling
Authors: Wang T. , Pei W. L. , Fu Y. , Hasegawa T. , Washiya T. , Saito H. , Ishio S. , Wang T. , Li F. S.
Published: January 2008

A [Co 0.4 nm/Pt 1 nm]8 multilayer with weak intergranular coupling was fabricated. The magnetization states after applying various negative fields along the easy axis were observed using a magnetic force microscope to reveal magnetization reversal behavior. Measurement results showed the magnetization reversal area separated into many small spots consisting of one or more grains. These spots reversed independently and the reversed spots did not expand at the boundary but remained stable while the negative magnetic field increased. A coherent rotation was further deduced by calculating the thermal activation volume by a dynamic coercivity method.
Micromagnetic simulation of magnetization reversal process and stray field behavior in Fe thin film wire
Authors: Ohno Munekazu , Yoh Kanji
Published: January 2008

The magnetization reversal process of Fe thin film wire is studied based on two-dimensional micromagnetic simulation. It is demonstrated that the external field parallel to the width direction results in the formation of a 180° Néel wall, whereas the field applied to the thickness direction yields the Bloch-like walls, which turn into C-type walls in the residual state. These behaviors are explained by the anisotropic dependence of wall energy in the direction of the external field. The stray field during this process is analyzed in detail.
Evidence for an energy level substructure of molecular states in helium droplets
Authors: Lehnig Rudolf , Blinov Nicholas V. , Jäger Wolfgang
Published: January 2008

The pure tunneling inversion transition of ammonia embedded in He4 droplets was investigated in the microwave frequency range. We observed a spectrum that consists of a sharp peak, only 15MHz wide, on top of a broad feature. The peculiar line shape could be simulated with an empirical model and is a clear experimental evidence for an energy level substructure of molecular states in doped helium droplets.
Calculations of codoping effects between combinations of donors (P/As/Sb) and acceptors (B/Ga/In) in Si
Authors: Ahn Chihak , Dunham Scott T.
Published: January 2008

We studied codoping effects in silicon using first-principles calculations, with particular attention to charge compensation, Coulomb interactions, and strain compensation. We find that for B-doped systems, As or Sb counter doping reduces the maximum hole concentration, but that due to strong binding of multiple P atoms, Ga or In counter doping can increase electron density in heavily P-doped material. For acceptor-acceptor pairing, we find the B-B interaction to be repulsive as expected due to Coulombic effects, but calculations show a surprisingly significant attractive binding between B and In, which we attribute to hole localization. However, B-In binding is not promising for enhancing hole concentration since BIn pairs are deep acceptors.
Optical characterization of Zn0.96Be0.04Se and Zn0.93Mg0.07Se mixed crystals
Authors: Hsu H. P. , Huang P. J. , Huang C. T. , Huang Y. S. , Firszt F. , Łęgowski S. , Męczyńska H. , Strzałkowski K. , Marasek A. , Tiong K. K.
Published: January 2008

A detailed optical characterization of Zn0.96Be0.04Se and Zn0.93Mg0.07Se mixed crystal samples grown by the modified high-pressure Bridgman method has been carried out via photoluminescence (PL), contactless electroreflectance (CER), and photoreflectance (PR) in the temperature range of 15–400 K. With these optical diagnostic tools we observed features originating from exciton emission, an edge emission due to recombination of shallow donor-acceptor pairs (DAPs), and a broad band related to recombination through deep-level defects, as well as band-edge and spin-orbit splitting critical points interband transitions in CER and PR experiments. The optical properties of these two mixed crystals are compared. Our comparative study revealed that the beneficial effect of beryllium (Be) incorporation is superior to that of magnesium (Mg), in the sense that a Be-containing ternary alloy resulted in better crystalline quality with more intense excitonic emission line and weaker DAPs and deep-level defect-related bands. The peak positions of the excitonic emission lines in the PL spectra correspond quite well to the energies of the fundamental transitions obtained by means of electromodulation spectra. The parameters that describe the temperature dependence of the fundamental and spin split-off band gaps, and the broadening function of the band-edge excitons, are evaluated and discussed.
Early steps of angiosperm–pollinator coevolution
Authors: Hu Shusheng , Dilcher David L. , Jarzen David M. , Winship Taylor David
Published: January 2008

The hypothesis that early flowering plants were insect-pollinated could be tested by an examination of the pollination biology of basal angiosperms and the pollination modes of fossil angiosperms. We provide data to show that early fossil angiosperms were insect-pollinated. Eighty-six percent of 29 extant basal angiosperm families have species that are zoophilous (of which 34% are specialized) and 17% of the families have species that are wind-pollinated, whereas basal eudicot families and basal monocot families more commonly have wind and specialized pollination modes (up to 78%). Character reconstruction based on recent molecular trees of angiosperms suggests that the most parsimonious result is that zoophily is the ancestral state. Combining pollen ornamentation, size, and aperture characteristics and the abundance of single-species pollen clumps of Cenomanian angiosperm-dispersed pollen species from the Dakota Formation demonstrates a dominance of zoophilous pollination (76% versus 24% wind pollination). The zoophilous pollen species have adaptations for pollination by generalist insects (39%), specialized pollen-collecting insects (27%), and other specialized pollinators (10%). These data quantify the presences of more specialized pollination modes during the mid-Cretaceous angiosperm diversification.
Dissection of the Carboxyl-Terminal Domain of the Proteasomal Subunit Rpn11 in Maintenance of Mitochondrial Structure and Function
Authors: Rinaldi Teresa , Hofmann Line , Gambadoro Alessia , Cossard Raynald , Livnat-Levanon Nurit , Glickman Michael H. , Frontali Laura , Delahodde Agnès
Published: January 2008

We have previously demonstrated that the C-terminal part of Rpn11, a deubiquitinating enzyme in the lid of the proteasome, is essential for maintaining a correct cell cycle and normal mitochondrial morphology and function. The two roles are apparently unlinked as the mitochondrial role is mapped to the Carboxy-terminus, whereas the catalytic deubiquitinating activity is found within the N-terminal region. The mitochondrial defects are observed in rpn11-m1 (originally termed mpr1-1), a mutation that generates Rpn11 lacking the last 31 amino acids. No mitochondrial phenotypes are recorded for mutations in the MPN+/JAMM motif. In the present study, we investigated the participation of the last 31 amino acids of the Rpn11 protein by analysis of intragenic revertants and site-specific mutants. We identified a putative α-helix necessary for the maintenance of a correct cell cycle and determined that a very short region at the C-terminus of Rpn11 is essential for the maintenance of tubular mitochondrial morphology. Furthermore, we show that expression of the C-terminal part of Rpn11 is able to complement in trans all of the rpn11-m1 mitochondrial phenotypes. Finally, we investigate the mechanisms by which Rpn11 controls the mitochondrial shape and show that Rpn11 may regulate the mitochondrial fission and tubulation processes.
Removal of S6K1 and S6K2 leads to divergent alterations in learning, memory, and synaptic plasticity
Authors: Antion Marcia D. , Merhav Maayan , Hoeffer Charles A. , Reis Gerald , Kozma Sara C. , Thomas George , Schuman Erin M. , Rosenblum Kobi , Klann Eric
Published: January 2008

Protein synthesis is required for the expression of enduring memories and long-lasting synaptic plasticity. During cellular proliferation and growth, S6 kinases (S6Ks) are activated and coordinate the synthesis of de novo proteins. We hypothesized that protein synthesis mediated by S6Ks is critical for the manifestation of learning, memory, and synaptic plasticity. We have tested this hypothesis with genetically engineered mice deficient for either S6K1 or S6K2. We have found that S6K1-deficient mice express an early-onset contextual fear memory deficit within one hour of training, a deficit in conditioned taste aversion (CTA), impaired Morris water maze acquisition, and hypoactive exploratory behavior. In contrast, S6K2-deficient mice exhibit decreased contextual fear memory seven days after training, a reduction in latent inhibition of CTA, and normal spatial learning in the Morris water maze. Surprisingly, neither S6K1- nor S6K2-deficient mice exhibited alterations in protein synthesis-dependent late-phase long-term potentiation (L-LTP). However, removal of S6K1, but not S6K2, compromised early-phase LTP expression. Furthermore, we observed that S6K1-deficient mice have elevated basal levels of Akt phosphorylation, which is further elevated following induction of L-LTP. Taken together, our findings demonstrate that removal of S6K1 leads to a distinct array of behavioral and synaptic plasticity phenotypes that are not mirrored by the removal of S6K2. Our observations suggest that neither gene by itself is required for L-LTP but instead may be required for other types of synaptic plasticity required for cognitive processing.
Geology and jungle fieldwork in eastern Indonesia
Authors: BAKER SIMON , HALL ROBERT , FORDE EMILY
Published: January 2008

Collecting geological information from the jungles and islands of eastern Indonesia depends largely on traditional fieldwork methods involving much footwork and messing about in boats. Coupled with modern laboratory and computing techniques, information gained on the ground is being used to interpret the tectonic development of east Indonesia, the Philippine Sea and the western Pacific.
QUANTUM YIELDS FOR ENZYME INACTIVATION AND THE AMINO ACID COMPOSITION OF PROTEINS*
Authors: McLaren A. D. , Hidalgo‐Salvatierra O.
Published: January 2008

Summary A formula has been derived which as a first approximation, predicts the quantum yields for the inactivation of enzymes. The enzymes can be divided into a group containing cystine and the subtilisins which do not. The formula applied to subtilisin gives good agreement. For some of the enzymes, only cystine needs to be considered in the calculation; for others good agreement is found if contributions from aromatic groups are included. On this basis a quantum yield for tobacco mosaic virus protein is computed as 0.0047 at 2537 Å.

The origin of chemically modified histidine in photochemically inactivated lysozyme has yet to be explained.
PHOTOTROPISM*
Authors: Thimann Kenneth V.
Published: January 2008

Summary Phototropic curvature is seen to varying degrees in all green plants from algae to orchids, and especially in seedlings, where it may assume life‐or‐death importance. It also occurs in a number of fungi. Recent work centers on the photorecptor, its action spectrum, the effector mechanism, and the inter‐relationships with normal growth.

The action spectrum for one type of phototropism of the oat seedling appears identical with that for the fungus Phycomyces and lies wholly in the blue and near u.v. It may indicate a carotenoid like lutein or possibly a flavin in non‐aqueous medium. Red light does not cause phototropism but can modify the response to the blue region. By analogy with the very similar phenomenon of geotropism, in which the georeceptor is probably a type of plastid, the photoreceptor is probably a specialized organelle which moves in a light gradient; this may be either one type of plastid or perhaps an unusual crystalline body which we have recently discovered in the oat seedling.

The effector mechanism in seedlings, which has been re‐investigated, is the lateral asymmetrical distribution of auxin, the amount of the shaded side becoming increased. Photodestruction of auxin appears to play no essential part. This asymmetrical distribution results from modification of the normal translocation mechanism, which is metabolically controlled. In fungi, however, the effector remains unknown.
U.V.‐INDUCED MITOTIC DELAY IN THE SEA URCHIN EGG*
Authors: Rustad Ronald C.
Published: January 2008

Summary Quantitative studies on u.v. and X‐ray‐induced mitotic delay in the sea urchin egg have been reviewed in order to discuss the nature of the target and the expression of the delay. U.V.‐induced division delay arises from damage to a single system which is also senstitive to X‐rays. Centrifugation can displace a sensitive cytoplasmic component into the centripetal half of the egg. This component may be of secondary importance, because no delay results from the irradiation of a small portion of the cytoplasm with a u.v. microbeam. The primary target is some component of the mitotic apparatus (chromosomes, centrioles, asters or spindle). The multiplication of centrioles is delayed.

Data concerning the u.v. action spectra, photoreactivation, and acridine orange damage additivity are consistent with the view that the primary target is a nucleic acid or nucleoprotein. Protein synthesis is required before the cell can pass through the radiation‐sensitive stage. The mitotic delay involves an inhibition of protein synthesis.
LIGHT ENERGY CONVERSION IN NEURONAL MEMBRANES*
Authors: Chalazonitis N.
Published: January 2008

Summary Photocurrents and decrease in membrane resistance have been shown by illuminating pigmented nerve cells, and vitally stained nerve fibers.

Any photocurrent, of threshold value, can elicit repetitive electrical activity as an extrinsic outward current dose. In pigmented nerve cells, photocurrents are additive to pre‐existing dark currents, thus modifying the frequency of the spontaneous activity.

Light effects on electrogenic membrane were compared to those of infra red. Both radiations decrease, with different yields, the membrane resistance. However, the initiated membrane currents are generally of opposite directions.

Similarly, opposite direction photocurrents are elicited by specific illuminations of two intracellular pigments (haemoprotein or carotenoid) in some nerve cells.

From spectrographic, respirometric and oscillographic evidences, the molecular mechanisms implied in the light energy conversion into membrane photocurrent can be considered as follows:

1. Release of electrons and hydrogen ions from dyes or natural pigments in molecular association with lipoproteins; secondary reactions of e and H+ with acceptors (dyes, or oxygen).

2. Secondary changes in adsorption bonds between dyes or pigments and associated lipoproteins resulting in changes in molecular orientations.

3. Directional fluxes of e, H+, and other ions, imitating fluxes elicited under a cathode during direct current flow.
FLASH PHOTOLYSIS IN HUMAN CONES*
Authors: Rushton W. A. H.
Published: January 2008

Summary 1. This paper is in three parts. Part I briefly summarizes the main facts and interpretations that are generally accepted as to the effect of light upon vision, adaptation and after‐images.

2. Part II considers in some detail the effect upon adaptation and after‐images of a flash of light sufficiently bright to generate abnormal visual pigments. A summary of these new findings is given at the end of Part II, together with a schema for the photoisomerization, bleaching and regeneration of cone pigments in the living eye.

3. Part III puts forward a rough mechanism that will account quantitatively for observed relations of brightness and threshold in adaptation. The manner in which flashes may modify this mechanism is suggested.
RESONANCE FLUORESCENCE IN CHLOROPHYLL a SOLUTIONS
Authors: Marcus Rudolph J. , Haugen Gilbert R.
Published: January 2008

Abstract— Chlorophyll a in aqueous hexane solutions has two fluorescence peaks, two fluorescence excitation peaks in the blue, and two fluorescence excitation peaks in the red. One of these set of peaks (excitation 2.34μ‐1 and 1.52μ‐1, fluorescence 1–50μ‐1) is identical with those found in methanol solutions of chlorophyll a and is assigned to an unaggregated species, while the other set of peaks (excitation 2.44μ‐1 and 1.475μ‐l, fluorescence 1.48μ‐l) is assigned to a species aggregated in the presence of water. The spectral shifts occurring in the aggregate follow the selection rules obtained by McRae and Kasha for a linear stack of parallel dye molecules. The sharply increased overlap of absorption and fluorescence leads to resonance fluorescence in the aggregate. The resonance fluorescence is demonstrated experimentally.
INACTIVATION OF A RHIZOBIUM BACTERIO‐PHAGE BY ULTRAVIOLET RADIATION OF DIFFERENT WAVE‐LENGTHS
Authors: Kleczkowski J. , Kleczkowski A.
Published: January 2008

Abstract— The action spectrum for inactivation of a Rhizobiurn bacteriophage by U.V. radiation follows the shape of the absorption spectrum of DNA between the wave‐lengths of 240 and 290 mμ (where inactivation probably reflects damage to the nucleic acid only), and deviates sharply upwards at wave‐lengths shorter than 240 mμ (where inactivation may depend on damage to both the nucleic acid, and protein of the phage). The rate of inactivation follows first order kinetics approximately at all wave‐lengths tested. Infectivity of the phage is halved when each mg of the phage nucleic acid has absorbed about 0 08 J of radiation energy at any wave‐length between 240 and 290 mμ.

The bacteriopharge can be photoreactivated after inactivation at any wave‐length between 230 and 290 mμ, but less so after inactivation at 230 mμ than at any wave‐length above 240 mμ. No evidence was found to suggest that dimerization of thymine residues of the phage‐DNA plays any part in the mechanism of inactivation of the bacteriophage by U.V. radiation.
THE PRODUCTION OF ELECTRONICALLY EXCITED OXYGEN MOLECULES AND THEIR REACTIONS WITH OZONE*
Authors: March R. E. , Furnival Sharon G. , Schiff H. I.
Published: January 2008

Abstract— The only detectable emission from discharged oxygen was a band system at 7619 Å. However, when a film of mercuric oxide was interposed between the discharge and the observation position, the intensity of this band was greatly enhanced and additional bands were observed at 6340, 7030 and at 12,700 Å, in agreement with the findings of Bader and Ogryzlo. A linear relationship, however, was found between the intensities at 6340 and at 12,700 Å, instead of the quadratic dependence reported by these authors.

A rapid reaction was found to occur between O3, and O2>(1Σ+g) molecules but the reappearance of the 7619 Å, emission after all the O3 had been reacted indicates a production process of O2(1Σ+g) molecules, probably from O2(1Δg).

The value of the rate constant for the reaction 02(1Σ+g) + O3→2O2+ O

is approximately 6times10‐13 cm3/molecule per sec. The rate constant for the comparable reaction with O2(1Δg) molecules is probably lower than this by a factor of at leat 4.
ABSOLUTE SPECTRAL SENSITIVITY OF PHOTOTUBES AND THE APPLICATION TO THE MEASUREMENT OF THE ABSOLUTE QUANTUM YIELDS OF CHEMILUMINESCENCE AND BIOLUMINESCENCE*
Authors: Lee John , Seliger H. H.
Published: January 2008

Abstract— Methods for the absolute measurement of the spectral sensitivity of phototubes are reviewed in detail. Several experimental arrangements are described for the independent determination of these values to insure the elimination of systematic error. On the basis of these measurements a rapid, simple technique is described for measuring the average absolute spectral sensitivity of a phototube over a defined emission spectrum, thus obviating the original tedious point‐by‐point methods and allowing frequent re‐Standardization. The application of these standardized phototubes to the measurement of the absolute quantum yields of the chemiluminescence of luminol and the bioluminescence of luminous bacteria and the firefly is described. An absolute low‐level light emission standard in the form of the luminol chemiluminescence reaction, either in aqueous or in the non‐aqueous solvent dimethylsulfoxide is proposed for general use and the conditions for its use are described in detail. It should therefore be possible for any researcher to obtain an absolute calibration, in his own experimental geometry, in the blue region of the spectrum.
INFLUENCE DE LA LUMIÈRE SUR LES MOUVEMENTS DE NUTATION DES PLANTULES
Authors: Rollin P.
Published: January 2008

Abstract— Red light can promote (a) the straightening of the curvature (Phaseolus vulgaris, Pisum sativum) (b) the formation of a loop (Phacelia tanacetifolia and Picea abies) or (c) the induction of a curvature which does not occur in the darkness (Lactuca sativa). Thesc red‐light induced movements could be reversed by following each brief red exposure with short irradiation by far‐red light. These reactions are controlled by the phytochrome system.

On the other hand, exposure to far‐red and blue light during a long period can induce other movements:

(a) The light re‐opens the hook which has been closed by red radiation (Lactuca sativa).

(b) The light induces the straightening of the dark‐induced curvature (Phacelia tanacetifolia). These facts may be due to an unknown property of phytochrome or to the action of another photoreceptor.
THE PHOTORECEPTORS INVOLVED IN ANTHOCYANIN SYNTHESIS
Authors: Vince D. , Grill R.
Published: January 2008

Abstract— Experiments with irradiation sequences where red precedes far‐red lead to the conclusion that, in turnip, phytochrome is the only pigment mediating anthocyanin synthesis in red and far‐red. Results from experiments where far‐red precedes red, however, suggest that more than one reaction is involved. A possible interpretation is that the ‘high‐energy’ reaction in far‐red and the low energy red/far‐red reversible reaction are mediated by two different forms of phytochrome.

The ‘high‐energy’ reaction in blue light does not appear to depend on phytochrome.
SEROLOGICAL PROPERTIES OF PORCINE TRYPSIN SUBSEQUENT TO INACTIVATION BY VARIOUS METHODS*
Authors: Ghiron C. A. , Barrett J. T. , Humber J. Y.
Published: January 2008

Abstract— Porcine trypsin was inactivated by various methods (heat, autolysis, photodynamic action, ultraviolet light, and gamma‐radiation) and the inactivated products were tested for their ability to precipitate porcine trypsin antiserum using the capillary fluid precipitin method. It was found that the chemical and structural modifications incurred with irradiation, sufficient to inactivate porcine trypsin, in contrast to heat and autolysis, did not interfere with those parts of the protein surface required for immunochemical reactivity.
TECHNIQUES FOR MEASURING FLUORESCENCE AND PHOSPHORESCENCE OF BIOLOGICAL MATERIALS*
Authors: Longworth J. W.
Published: January 2008

Abstract— Techniques and instruments for measuring the luminescence, fluorescence. and phosphorescence of proteins and nucleic acids are described. Emphasis is placed on the principles of the instruments and the procedures which are necessary to measure quantitatively the luminescence from biological macromolecules at 77°K. Examples are given of the effect of denaturation on luminescence of both proteins and nucleic acids. on ways in which the luminescence can be associated with particular constituents, and finally on the influence that electronic energy transfer has on the excitation spectra of protein luminescences. These examples typify the relationship of luminescence spectra to the conformation and constitution of macromolecules.
THE IMPORTANCE OF THE MICROENVIRONMENT SURROUNDING A CHROMOPHORE IN DETERMINING ITS SPECTROSCOPIC BEHAVIOR*
Authors: KOUDELKA JAROMIR , AUGENSTEIN LEROY
Published: January 2008

Se pone especial énfasis en la importancia del microambiente de un grupo como factor determinante del comportamiento fotoquímico, emisión y dicroismo circular de móleculas biológicas. Los ejemplos dados incluyen la fotoquímica de la ribonucleasa, la dependencia de las propiedades luminiscentes de amino acidos aromáticos con la temperatura, y el comportamiento espectroscópico de los dinucleótidos.
SOME REACTIONS OF PHOTOCHEMICALLY GENERATED PERFLUOROMETHOXYL AND RELATED OXYGENATED DERIVATIVES OF THE PERFLUOROMETHYL RADICAL
Authors: AYMONINO P. J.
Published: January 2008

Abstract— Results of some reactions of photochemically produced perfluoromethoxyl and related radicals are presented, including a kinetic study of the photochemical reaction between fluoroxyperfluoromethane (CF3OF) and carbon monoxide leading quantitatively to perfluoromethyl fluoroformate (CF3OC(O)F).

Bis (perfluoromethyl) oxalate (CF3OC(O)C(O)OCF3), the supposed chain‐ending product of the named reaction is described for the first time. Also, some evidences are presented in favor of the existence of bis(perfluoromethyl)peroxydicarbonate (CF3OC(O)OOC(O)OCF3) and of the mixed mono(perfluoromethyl)ester‐monofluoride of peroxydicarbonic acid (CF3OC(O)OOC(O)F), which are believed to be respectively the chain‐ending products of the oxidation of carbon monoxide, photochemically sensitized by bis (perfluoromethyl)peroxide and fluoroxyperfluoromethane.

Finally, a description is given of a novel synthetic method which gives high yields of bis (perfluoromethyl)trioxide, depending on the oxidation of perfluoromethyl radicals produced photochemically from a mixture of fluorine and perfluoroacetone.

Se presentan los resultados de algunas reacciones que llevan a la producción fotoquímica de perfluorometoxilo y otros radicales análogos, incluyendo un estudio cinético de la reacción fotoquímica entre el fluoroxiperfluorometano (CF3OF) y el monóxido de carbono, con formación cuantitativa de fluoroformiato de perfluorometilo (CF3OC(O)F). Se describe por primera vez el oxalato de perfluorometilo (CF3OC(O)C(O)OCF3) que es justamente el producto final de la cadena de la mencionada reacción. También se presentan evidencias en favor de la existencia del peroxidicarbonato de perfluorometilo (CF3OC(O)OOC(O)OCF3) y del éster perfluorometílico del monofluoruro del ácido peroxidicarbónico (CF3OC(O)OOC(O)F), los cuales se cree son respectivamente los productos finales de la cadena de la oxidación del monóxido de carbono sensibilizada fotoquímicamente por el peróxido de perfluorometilo y el fluoroxiperfluorometano.

Finalmente se da una descripción de un nuevo método sintético el cual da altos rendimientos de trióxido de perfluorometilo, dependiendo de la oxidación de radicales perfluorometilo producidos fotoquímicamente a partir de una mezcla de fluor y perfluoroacetona.
PHOTOCHEMICAL ADDITION REACTIONS TO α,β‐UNSATURATED KETO‐STEROIDS
Authors: CRABBÉ PIERRE , CRUZ ALICIA , IRIARTE JOSÉ
Published: January 2008

Abstract— Several examples of photochemical cycloaddition of olefins to α,β‐unsaturated ketones have been reported, but there are only a few cases of formation of substituted cyclobutane or cyclobutene rings through such ieactions[1–4]. We wish to report here photochemical addition reactions to positions 16 and 17 of the steroid nucleus, using the conjugated system of 3β‐hydroxypregna‐5,16‐dien‐20‐one acetate (1) as a substrate [5].

Han sido reportados algunos ejemplos de cicloadición fotoquímica de olefinas a cetonas conjugadas, pero hay pocos casos de formación de anillos ciclobutánicos o ciclobuténicos mediante estas reacciones.
Semiautomatic vertebrae visualization, detection, and identification for online palliative radiotherapy of bone metastases of the spinea)
Authors: Létourneau Daniel , Kaus Michael , Wong Rebecca , Vloet Anita , Fitzpatrick David A. , Gospodarowicz Mary , Jaffray David A.
Published: January 2008

A treatment process which integrates simulation, planning, and delivery in one single session of on a treatment unit capable of cone‐beam CT imaging (CBCT) is under development in our institution for palliation of spinal metastases. The objective of this work is to develop and validate a semiautomatic vertebra detection and identification algorithm to streamline the target definition process and improve the consistency of online planning on cone‐beam CT data sets while the patient is on the treatment couch. Key issues pertaining to this work are the limited field of view and image quality of CBCT, the inter‐ and intrapatient variation of vertebra morphology, and the spine curvature. An initial library of ten patient CBCT data sets was used to derive the vertebra detection and identification method and set the parameters used by the algorithm. In this method, sagittal and coronal “curved” digitally reconstructed radiographs (cDRRs) are first created by projecting a subvolume of the CBCT data orthogonally to the centerline of a cylinder model positioned manually. The detection of the vertebra centers is then performed on the cDRRs based on an edge detection algorithm. The identification of the vertebrae by name is based on the detection of one or more of four different reference anatomical landmarks on cDRRs. The validation of the vertebra detection and identification algorithm was performed on a library of 27 patient CBCT data sets with an average detection success rate of and for sagittal and coronal cDRRs, respectively, for three different users. The entire process including manual steps and user approval was performed on average in 3.23–3.45 min (, three users), with only 0.14 min for the automatic detection and identification of the vertebrae. The semiautomatic identification and segmentation of vertebrae on CBCT images was shown to be robust and effective. The next step will be the clinical implementation of the algorithm within the online planning and delivery treatment technique for patients with spinal bone metastases.
Anniversary Paper: Roles of medical physicists and health care applications of informatics
Authors: Kagadis George C. , Nagy Paul , Langer Steve , Flynn Michael , Starkschall George
Published: January 2008

Over the past 100 years, both diagnostic radiology and radiation therapy have grown from infancy to maturity. Accompanying this growth, the discipline of medical physics has evolved and advanced accordingly. New diagnostic and therapeutic procedures continue to be developed, for example, multidetector computed tomography, multileaf collimation, magnetic resonance imaging, dual‐source computed tomography, and intensity‐modulated radiation therapy. These are now incorporated in health care facilities throughout the world. Modern technologies such as these provide information on underlying pathology at increasingly higher resolutions, generating more information; thus requiring complex methods of image recording and storage. The management of the storage and retrieval of accumulated information is a domain of informatics. In this short review, we describe the different roles of medical physicists and the effective contribution of the American Association of Physicists in Medicine in the evolution of informatics. Medical physicists have contributed to the development of informatics in numerous ways, such as designing hospital information systems and infrastructures that better serve radiologists and other physicians. In addition, the positive exploitation of knowledge gathered in medical settings and effective interdisciplinary collaborations between scientists of different backgrounds have increased. These developments provide future medical physicists the opportunity to develop strategic roles in information technology and thus better contribute to health care.
MOBILE HCI 07
Authors: Lee Newton
Published: January 2008

MobileHCI is a conference that provides practicioners and researchers a common forum to discuss about the challenges, potential solutions and innovations towards effective interaction with mobile systems and services.
A time to retrospect and prospect
Authors: Gotlieb Calvin C.
Published: January 2008

As noted in these introductory pages, Alan Perlis was the founding Editor-in-Chief (EIC) of
Communications
, with the first issue debuting in January 1958. He resigned upon being elected ACM President in June 1962. During his tenure, CACM content was organized into departments, such as "Scientific Applications," "Standards," "Programming Languages," among others. I was the editor of a section on "Business Applications."
In the realm of insight and creativity
Authors: Bentley Jon
Published: January 2008

The intellectual pleasures and financial rewards of solving one programming problem, it turns out, are just the prelude to solving many more.
Information security: 50 years behind, 50 years ahead
Authors: Diffie Whitfield
Published: January 2008

Trust among people and organizations will be even more critical in securing communications and commerce in the future networked environment.
Inspiration and trust
Authors: Spafford Eugene H.
Published: January 2008

Not every important problem can be solved through science and technology, but that doesn't mean they shouldn't be addressed.
Increasing the accessibility of pen-based technology
Authors: Moffatt Karyn
Published: January 2008

This paper describes the author's dissertation research on improving the accessibility of pen-based technology. The first step for this research was to gather information on the underlying causes of target acquisition difficulty. To meet this goal, a controlled laboratory study was conducted, which uncovered three sources of difficulty: slipping, drifting, and missing just below. The remaining work will be to address these difficulties by implementing new interaction techniques and experimentally evaluating their effectiveness.
Online support communities for older people
Authors: Pfeil Ulrike
Published: January 2008

My PhD research aims to identify the components of social support in online support communities for older people. Findings will show how older people support each other in these online communities and how they form a social network based on their communication activities. In addition, my PhD research will reveal how different characteristics of social support evolve and change over time. I will investigate how relationships between older people form, dissolve, and are reconstructed within online support communities, and how individual members are integrated and take on certain roles and responsibilities within the community. Based on the findings, a descriptive model that conceptualises the exchange of social support in online support communities for older people will be developed.
Efficiency of physical carrier sensing in wireless access networks
Authors: Cesana M. , Campelli L. , Borgonovo F.
Published: January 2008

We propose an analytical approach for evaluating the impact of physical carrier sensing in simple wireless access networks. We describe the system through a time-continuous Markov Chain, and we gather from its solution performance measures in terms of throughput and collision probability. We derive qualitative dimensioning criteria for the carrier sensing itself under different network conditions.
OPSS
Authors: Bracciale Lorenzo , Piccolo Francesca Lo , Luzzi Dario , Salsano Stefano
Published: January 2008

In this paper we present OPSS, an Overlay Peer-to-peer Streaming Simulator designed to simulate large scale (i.e. in the order of 100K nodes) peer-to-peer streaming systems. OPSS is able to simulate a fair (i.e. "TCP-like") sharing of the uplink and downlink bandwidth among different connections, and it guarantees extensibility by allowing the implementation of different peer-to-peer streaming algorithms as separate modules. Source code of OPSS is available under the GPL license.