Extended Time Interval Research Articles

Huygens Probe descent dynamics inferred from Channel B signal level measurements

The signal strength of the Huygens Probe Channel B transmission to the Cassini Orbiter was monitored during the Probe descent through Titan's atmosphere on 14 January 2005. A model of the Probe motion during the mission was constructed to include Probe spin, coning motion and tilt caused by varying wind speeds. This simple model is sufficient to reproduce the most prominent features seen in the signal level measurements. It provides estimates of the coning and tilt angles as well as the direction of the Huygens coordinate axes over extended time intervals in the mission.

Motor memory preservation in aged monkeys mirrors that of aged humans on a similar task

We studied long-term motor memory preservation in rhesus monkeys tested on a task similar to that employed in humans. First, motor speed and rate of motor decline was measured in 23 animals ranging from 4 to 26 years old. The task for the animals consisted of removing a food reward from a curved rod within the inner chamber of an automated panel. Young animals performed twice as fast as the aged animals. Second, young ( n = 6) and aged ( n = 10) animals were re-tested 1 year later on the same task with no intervening practice. We anticipated a decline in motor speed of 144 ms/year, instead the average performance time recorded during the repeat session improved significantly by 17% in the aged animals. This finding mirrors that of a longitudinal study conducted in humans using a similar test panel and supports that, while initial performance times of a novel motor task decline with age, motor memory traces are preserved over an extended time interval, even without continued practice. The data also support that the rhesus monkey could be used as a model to study the mechanisms by which long-term retention of motor memory occurs in aging.

Radiation Recall Pneumonitis Induced by Gemcitabine

Radiation recall pneumonitis describes a very rare reaction in a previously irradiated area of pulmonary tissue after application of pharmacological agents. A case of recall pneumonitis induced by gemcitabine is reported. A 64-year-old female patient with metastasized esophageal carcinoma received simultaneous chemoradiotherapy of the upper mediastinum with 50.4 Gy and cisplatin/5-fluorouracil. 8 months later she was scheduled for salvage chemotherapy with gemcitabine (1,000 mg/m(2) days 1 and 8) and docetaxel (75 mg/m(2) day 8) due to locally progressive disease. After having received gemcitabine on day 1 of the second course, the patient developed dry cough, subfebrile temperatures and dyspnea within 48 h. A CT of the thorax revealed newly developed bilateral pulmonary ground-glass opacity corresponding to the previous radiation fields. Chemotherapy was stopped and systemic application of prednisolone was initiated. 2 months later symptoms had resolved with a control CT of the thorax showing complete regression of the pulmonary changes. Gemcitabine-induced recall pneumonitis is a rarely reported phenomenon and should be taken into account even after extended time interval to the previous radiotherapy.

Age as a determinant of reproductive success among captive female rhesus macaques (Macaca mulatta)

A retrospective analysis was performed on fertility outcomes among a colony of captive Indian rhesus monkeys. The analysis covered over 30 years and was based on 1443 females with a total of 11,453 pregnancies. Various determinants of fertility were assessed including birth rates, pregnancy loss, infant survival, interbirth intervals, and interval from last birth to death. Binary variables were analyzed with generalized linear models with random intercepts, while linear mixed models were used for analysis of continuous variables. Age of the dam was a significant factor in determining whether a pregnancy resulted in a birth and whether an infant survived the first 30 days with primiparous or older mothers being less likely to produce an infant surviving to that age. In contrast, sex proved to be the only significant factor in determining whether an infant lived to 1 year, with females being more likely to survive. The interval between births proved to be affected primarily by dam age, while the late death of an infant depressed the likelihood of an extended time interval between her last birth and her death. Overall, these results demonstrate that maternal age contributes significantly to a decline in fertility and older females can live relatively long periods following birth of their last infant.

Generation of sub-micron particles and secondary pollutants from building materials by ozone reaction

This study reports results from two different experiments examining reactions between ozone and common building materials that can lead to the formation of secondary products and particulate-phase materials. Monitored species include sub-micron particles and volatile organic compounds (VOCs). In the first set of experiments, various building materials were placed in a 20 L stainless-steel chamber and exposed to ozone. The materials included expanded polystyrene, a natural rubber adhesive, cedar board, Japanese Cyprus board and silver fir board, as well as d-limonene, which is a known constituent of certain woods and cleaning products. The combination of ozone and either d-limonene, cedar board or cypress board produced sub-micron particles, with most of the increase occurring in the size range of 0.01– 0.5 μ m diameter. This was not observed for the other materials. In the case of cedar board, the consequence of ozone exposure over an extended time interval was monitored. As the exposure time elapsed, the concentration of sub-micron particles moderately decreased. In the second set of experiments, unwaxed or waxed plastic tiles were placed in the 20 L chamber and exposed to ozone. Sub-micron particles and organic compounds were measured during the course of the experiments. In the case of the waxed tile, the number of 0.01– 1.0 μ m size particles grew about 50 × 10 8 particles m - 3 ; particle growth was significantly less for the un-waxed tile. For both the waxed and un-waxed tiles, the emission rates of heptane, nonane, nonanal, and decanal increased after ozone was added to the supply air. (However, it is not clear if some or all of this production was due to ozone reacting with the sorbent used for sampling or with compounds captured by the sorbent.) This study provides further evidence that ozone-initiated reactions with building materials can be a significant source of both sub-micron particles and secondary organic compounds in indoor environments.

Endocrine Alterations Associated with Extended Time Interval Between Estrus and Ovulation in High-Yield Dairy Cows

Short fertile half-lives of the male and female gametes in the female tract necessitate accurate timing of artificial insemination. We examined the possible association between extension of the estrus to ovulation (E-O) interval and alterations in concentrations of estradiol, progesterone, and the preovulatory LH surge before estrus and ovulation. High-yielding Holstein cows (n = 74 from a total of 106) were synchronized and were examined around the time of the subsequent estrus. They were observed continuously for estrual behavior. Blood samples were collected before and after estrus, and ultrasound checks for ovulation were made every 4h. About three-quarters of the cows exhibited short (but normal) E-O intervals of 22 to 25h (25%) or normal intervals of 25 to 30h (47%); 17% of them displayed a long (but normal) E-O interval of 31 to 35h, and about 10% exhibited a very long E-O interval of 35 to 50h. Extended E-O interval comprised estrus-to-LH surge and LH surge-to-ovulation intervals that were both longer than normal. Pronounced changes in hormonal concentrations were noted before ovulation in the very long E-O interval group of cows: progesterone and estradiol concentrations were reduced, and the preovulatory LH peak surge was markedly less than in the other 3 groups. Postovulation progesterone concentrations during the midluteal phase were lesser in the very long and the long E-O interval groups compared with those in the short and normal interval groups. Season, parity, milk yield, and body condition did not affect the estrus to LH surge, LH surge to ovulation, and E-O intervals. The results indicate an association between preovulatory-reduced estradiol concentrations and a small preovulatory LH surge, on the one hand, and an extended E-O interval, on the other hand. Delayed ovulation could cause nonoptimal timing of AI, a less than normal preovulatory LH surge that may be associated with suboptimal maturation of the oocyte before ovulation, or reduced progesterone concentrations before and after ovulation. All may be factors associated with poor fertility in cows with a very long E-O interval.

Platelet-Rich Plasma (PRP) Utilized to Promote Greater Graft Volume Retention in Autologous Fat Grafting

Objectives: Autologous fat theoretically provides one of the most ideal mediums for soft-tissue augmentation and reconstruction, although its clinical applications have been marked with skepticism because of its documented unreliable survival. Over the years, numerous unsuccessful efforts have set forth to elucidate modifications in the application process of autologous fat grafts to allow the medium greater clinical predictability. This study aims to investigate the effects of platelet-rich plasma (PRP) on autologous fat grafts when used in conjunction with each other in soft tissue augmentation and reconstruction. Study Design: Retrospective review, over a 30-month period, of consecutive patients with results greater than 6 months in duration. Methods: This study is based on clinical experiences representing 2033 grafts in 448 consecutive patients using PRP additives and in the previous 132 patients who had syringe harvest without use of PRP. All PRP isolates were harvested via the Smart Prep system. Harvest and augmentation techniques are discussed and representative results are presented. Results: Results were based on clinical observations and patient satisfaction. Of the 580 patients in the experimental group, essentially all showed greater graft volume retention over extended time intervals compared with control subjects (nongraft areas). Patients in the PRP-added experimental group displayed less postoperative ecchymosis and edema, which also led to greater patient satisfaction in this group. Conclusion: Adding PRP to autologous fat aids in graft volume retention and survival when used clinically for soft-tissue augmentation and reconstruction.

Intracerebral Hematoma

See related article, pages 2457–2462. The signs and symptoms of acute intracranial hemorrhage are those of a rapidly developing mass lesion, compounded over time by surrounding edema, and sometimes by brain herniation. These are dramatic, debilitating, and often fatal events, but does the pathophysiology of intracranial hemorrhage extend beyond that of mass effect? Blood contains several factors that are potentially, and in some cases definitively, neurotoxic. Chief among these are hemoglobin and its breakdown products, heme and iron, which exhibit neurotoxicity at low micromolar concentrations through mechanisms involving iron-catalyzed production of reactive oxygen species.1,2 Brain has …

Recombination of photodissociated iodine: A time-resolved x-ray-diffraction study

A time-resolved x-ray-diffraction experiment is presented that aims to study the recombination of laser-dissociated iodine molecules dissolved in CCl4. This process is monitored over an extended time interval from pico- to microseconds. The variations of atom-atom distances are probed with a milliangstrom resolution. A recent theory of time-resolved x-ray diffraction is used to analyze the experimental data; it employs the correlation function approach of statistical mechanics. The most striking outcome of this study is the experimental determination of time-dependent I-I atom-atom distribution functions. The structure of the CCl4 solvent changes simultaneously; the solvent thus appears as a reaction partner rather than an inert medium hosting it. Thermal expansion of the system is nonuniform in time, an effect due to the presence of the acoustic horizon. One concludes that a time-resolved x-ray diffraction permits real-time visualization of solvent and solute motions during a chemical reaction.

Fluorine containing nonsymmetrical five-ring achiral banana-shaped compounds with columnar and synclinic antiferroelectric layered phases.

The phase transitional behavior of two homologous series of five-ring banana-shaped compounds comprising fluorine substituents synthesized through covalent linking of two chemically dissimilar rod-like anisometric cores (arms) to central 1,3-phenylene is reported. The novelty of these molecules originates from the fact that the molecules are highly nonsymmetrical. One of the arms, which is either salicylaldimine or Schiff base core, possesses two vicinal fluorine atoms at the terminal ring having a -decyloxy tail; while the -alkyl tail attached to the other arm was varied to realize a homologous series of compounds. The mesophases have been characterized by several complementary studies. The banana-shaped systems having short or medium alkyl chain lengths form apolar columnar (two-dimensional) structures, while on ascending the series, a polar smectic phase is stabilized. Detailed electro-optical investigations on one of the polar smectic phases revealed a synclinic antiferroelectric (racemic) ground state structure, which switches, as expected, to an anticlinic ferroelectric state by the application of an electrical field. At higher field strengths applied for an extended time interval, the anticlinic ferroelectric state switches to a synclinic ferroelectric (chiral) state. Upon field removal, these domains switch to an anticlinic antiferroelectric (chiral) state, which eventually nucleates to the original antiferroelectric synclinic (racemic) state. Remarkably, the associated spontaneous polarization value exceeds 800 nC cm, which is among the highest reported hitherto.

MAGNETIC CLOUDS: A SUBJECT OF SPACE WEATHER PREDICTION

Magnetic clouds are ideal objects for solar-terrestrial studies because of their simplicity and their extended time intervals of southward and northward magnetic fields. Magnetic clouds constitute a significant subset of coronal mass ejections with remarkable characteristics in the interplanetary medium and a strong influence on the Earth's magnetosphere, giving rise to geomagnetic storms. The evolution of such a cloud from the neighborhood of the Sun up to the Earth is numerically simulated for two cases, without and with a presence of a faster moving shock front. Its influence on the magnetosphere can be seen by the triggered geomagnetic storm. Therefore, magnetic clouds are an important subject for space weather predictions.

Removal of the OptEase Retrievable Vena Cava Filter Is Not Feasible after Extended Time Periods Because of Filter Protrusion Through the Vena Cava

Therapeutic and prophylactic vena cava filters (VCFs) are used to prevent pulmonary embolism. Concerns exist over placing a permanent filter in a young trauma patient. Recently, retrievable VCFs have become available. One such filter is the OptEase, which has a recommended time of removal of up to 23 days after insertion. Data supporting this recommendation are sparse. Many trauma patients will need filters for more than 2 weeks, and there are no data evaluating the safety of removal after extended time periods. The purpose of this study was to determine the safety, feasibility, and reaction of the vena cava when removing the OptEase retrievable VCF at different time intervals. Twenty Yorkshire cross pigs (80-113 kg) underwent general anesthesia with tiletamine and zolazepam. Filters were placed in the infrarenal vena cava (VC) through the femoral vein under fluoroscopic guidance. Animals were then divided into four groups. In group 1, filters were removed at 14 days; in group 2, at 30 days; in group 3, at 60 days; and in group 4, at 90 days. Removal was attempted using a snare-and-sheath technique through the femoral vein. Animals with successful filter removal were allowed to recover; then, the animals underwent autopsy (gross and microscopic VC examination) 2 months later. Animals with unsuccessful filter removal underwent autopsy immediately after attempted removal. Venacavograms were taken at filter insertion, at removal, and before autopsy to evaluate any VC abnormalities. Successful removal of the filter in all five pigs (100%) was reliably performed only in the 14-day group. In this group, the initial VC transverse diameter was 19.4 +/- 0.8 mm and was significantly reduced to 9.8 +/- 1.1 mm (p < 0.05) immediately after removal. Sixty days later, before autopsy, VC diameter had increased to 15.3 +/- 1.9 mm, which was significantly larger than at removal (p < 0.05) but not different from the initial value. In the 30-day group, removal was successful in only one of five animals. Although removal was successful in the one pig, autopsy at 2 months postremoval revealed total occlusion of the VC. Filters could not be removed from 60- and 90-day groups. At autopsy, the VCF struts were embedded or protruded through the VC wall. Microscopic examination of the VC revealed significant scarring underneath and between the struts. Removal of the retrievable OptEase VCF may be successfully performed up to 14 days after insertion. Strut protrusion through the VC wall prohibited successful and safe removal at extended time intervals.

Distributed communication and psychosocial performance in simulated space dwelling groups

The present report describes the development and application of a distributed interactive multi-person simulation in a computer-generated planetary environment as an experimental test bed for modeling the human performance effects of variations in the types of communication modes available, and in the types of stress and incentive conditions underlying the completion of mission goals. The results demonstrated a high degree of interchangeability between communication modes (audio, text) when one mode was not available. Additionally, the addition of time pressure stress to complete tasks resulted in a reduction in performance effectiveness, and these performance reductions were ameliorated via the introduction of positive incentives contingent upon improved performances. The results obtained confirmed that cooperative and productive psychosocial interactions can be maintained between individually isolated and dispersed members of simulated spaceflight crews communicating and problem-solving effectively over extended time intervals without the benefit of one another's physical presence.

Age does not increase rate of forgetting over weeks—Neuroanatomical volumes and visual memory across the adult life-span

The aim of the study was to investigate whether age affects visual memory retention across extended time intervals. In addition, we wanted to study how memory capabilities across different time intervals are related to the volume of different neuroanatomical structures (right hippocampus, right cortex, right white matter). One test of recognition (CVMT) and one test of recall (Rey-Osterrieth Complex Figure Test) were administered, giving measures of immediate recognition/recall, 20-30 min recognition/recall, and recognition/recall at a mean of 75 days. Volumetric measures of right hemisphere hippocampus, cortex, and white matter were obtained through an automated labelling procedure of MRI recordings. Results did not demonstrate a steeper rate of forgetting for older participants when the retention intervals were increased, indicating that older people have spared ability to retain information in the long-term store. Differences in neuroanatomical volumes could explain up to 36% of the variance in memory performance, but were not significantly related to rates of forgetting. Cortical volume and hippocampal volume were in some cases independent as predictors of memory function. Generally, cortical volume was a better predictor of recognition memory than hippocampal volume, while the 2 structures did not differ in their predictive power of recall abilities. While neuroanatomical volumetric differences can explain some of the differences in memory functioning between younger and older persons, the hippocampus does not seem to be unique in this respect.

Electrocatalytic oxidations of biological molecules (ascorbic acid and uric acids) at highly oxidized electrodes

Highly oxidized glassy carbon and other metal (gold and platinum) electrode surfaces were generated by applying 2.0 V vs. SCE for 600 s in pH 7 solution. The effects of oxidation on the functional, physical, and chemical characteristics of the electrodes went beyond the usual conditioning of such electrode surfaces through cycling to slightly beyond the medium decomposition potentials. The oxidized electrodes showed enhanced electrochemical activities and lower background currents. Besides cleaning the surface of contaminants introduced in the polishing stage of electrode preparation, application of such high potentials for an extended time interval changed the chemical nature of the glassy carbon surface itself. The chemical changes influenced the electro-oxidation reaction of bio-molecules such as ascorbic acid and uric acid but did not influence the reaction of the ferri- and ferrocyanide system. As a result the biological molecules (uric acid and ascorbic acid) were detected using an electrochemical method individually and simultaneously without the necessity for any electron relay complex.

Reconstruction of the magnetopause and low-latitude boundary layer topology using Cluster multi-point measurements

Abstract. Multi-spacecraft data from Cluster allow for a more detailed magnetopause and boundary layer structure determination than ever before. Reconstruction methods, in which the time variability observed during a pass is interpreted as being due to boundary motion and/or spatial structure, are particularly well suited for this task. Such methods rely on the availability of plasma and field data and adopt the tangential discontinuity hypothesis to determine the motion, acceleration, boundary structure, boundary curvature and surface wave speed over an extended time interval. In this paper one- and two-dimensional reconstruction methods are applied to multi-spacecraft data for the first time.

Distributed interactive communication in simulated space-dwelling groups

This report describes the development and preliminary application of an experimental test bed for modeling human behavior in the context of a computer generated environment to analyze the effects of variations in communication modalities, incentives and stressful conditions. In addition to detailing the methodological development of a simulated task environment that provides for electronic monitoring and recording of individual and group behavior, the initial substantive findings from an experimental analysis of distributed interactive communication in simulated space dwelling groups are described. Crews of three members each (male and female) participated in simulated “planetary missions” based upon a synthetic scenario task that required identification, collection, and analysis of geologic specimens with a range of grade values. The results of these preliminary studies showed clearly that cooperative and productive interactions were maintained between individually isolated and distributed individuals communicating and problem-solving effectively in a computer-generated “planetary” environment over extended time intervals without benefit of one another's physical presence. Studies on communication channel constraints confirmed the functional interchangeability between available modalities with the highest degree of interchangeability occurring between Audio and Text modes of communication. The effects of task-related incentives were determined by the conditions under which they were available with Positive Incentives effectively attenuating decrements in performance under stressful time pressure.

Reconstruction of solar activity for the last millennium using $^\mathsf{10}$Be data

In a recent paper (Usoskin et al. 2002a), we have reconstructed the concentration of the cosmogenic 10 Be isotope in ice cores from the measured sunspot numbers by using physical models for 10 Be production in the Earth's atmosphere, cosmic ray transport in the heliosphere, and evolution of the Sun's open magnetic flux. Here we take the opposite route: starting from the 10 Be concentration measured in ice cores from Antarctica and Greenland, we invert the models in order to reconstruct the 11-year averaged sunspot numbers since 850 AD. The inversion method is validated by comparing the reconstructed sunspot numbers with the directly observed sunspot record since 1610. The reconstructed sunspot record exhibits a prominent period of about 600 years, in agreement with earlier observations based on cosmogenic isotopes. Also, there is evidence for the century scale Gleissberg cycle and a number of shorter quasi-periodicities whose periods seem to fluctuate in the millennium time scale. This invalidates the earlier extrapolation of multi-harmonic representation of sunspot activity over extended time intervals.

Dynamics of Synchronising Systems

11R5. Dynamics of Synchronising Systems. - RF Nagaev (Dachny pr 9-2-66, St Petersburg, 198255, Russia). Springer-Verlag, Berlin. 2003. 326 pp. ISBN 3-540-44195-6. $149.00.Reviewed by I Andrianov (Inst fur Allgemeine Mechanik, RWTH, Templergraben 64, Aachen, D-52056, Germany).This book is monograph on the use of the averaging technique for solving the problems of theoretical, quantum and applied mechanics. The book is aimed at both graduate and postgraduate students as well as researchers in mechanics and physics with university or equivalent education. It is assumed that the reader has a basic knowledge of analytical mechanics, theory of nonlinear oscillations, rigid-body dynamics, quantum mechanics and electrical engineering, as well as of mathematics in the framework of a basic course taught at a technical university. The book is divided into 11 chapters. Chapter 1 is devoted to the concept of local integrability and consideration of possibilities of the choice of small parameters. Chapter 2 contains a brief description of mechanical and electromechanical systems that can be considered as being conservative. In Chapter 3 and 4 the single-and multivariable systems in “action-angle” variables are analyzed. In Chapter 5 multifrequency averaging of the system with a multidimensional rapidly rotating phase is carried out by a modified averaging procedure. Usage of canonical averaging of the equations of quantum mechanics, in particular the Schro¨dinger’s equation with various potentials, made it possible to obtain a solution in a more appropriate form than on the basis of the spectral analysis (Chapter 6). In Chapters 7, 8, and 10 the problems of weak interactions of quasiconservative dynamic systems are studied. Interesting effects of synchronization are discovered and studied. Periodic solutions in problems of excitation of mechanical oscillations form the subject of Chapter 11. It is noteworthy that all solutions obtained are valid for finite, but relatively extended time intervals. The book is very interesting from the standpoint of practically usable important results as well as for further development of averaging procedure. The subject index is informative, but somewhat short. The quality of the figures is high, but, unfortunately, no captions are included. References contain mainly papers and books written in Russian, just as Russian books now have been translated into English. Moreover, practically all-Russian journals referred to are cover-to-cover translated into English. For example, MTT is translated as Mechanics of Solids, PMM as PMM J Appl Math Mech, etc. It may therefore be more natural and convenient for readers to refer to English translations. This skillfully written book is a reader-friendly and well-organized textbook in the field of mathematical mechanics. As a rule, each section includes a pedagogical introduction. Dynamics of Synchronising Systems is highly recommended for purchase by both individuals and libraries.

Investment Strategies in Private Equity

We present a method for localised two-photon photoconversion of fluorescent cells within distinct microanatomical compartments in intact lymph nodes. This method allows efficient photoconversion of whole cell populations as well as of single cells while preserving cell viability and motility. Moreover, the combination of high-speed image acquisition and real-time display permits us to target and lock-on to individual cells for photoconversion as they migrate within the lymph node. Optical cell marking makes it possible to differentiate otherwise homogenous responding cells based on their microanatomical location. It also enables discontinuous in vivo tracking of cell fates to distal sites after extended time intervals.