bluuebunny/crossref_metadata_2025 huggingface dataset:
Shipboard Organization – the Choices for International Shipping
Authors: Dyer-Smith Martyn B. A.
Published: October 2009

Navigating officers at sea have duties other than watchkeeping and navigation. This paper considers the problems associated with a seagoing career in the context of social and technical developments. The worldwide pool of skilled maritime labour is rapidly diminishing and steadily ageing. Seafaring as a career is becoming progressively less attractive. Worldwide shortages of qualified staff are predicted to get far worse with serious commercial consequences, but it may be that further reductions in crewing levels will merely exacerbate the problem. The psychological difficulties of present-day seafaring are considered and a sociotechnical re-design of the shipboard system discussed as an option.
The Fisherman – Navigating to the Plaice
Authors: Knox Ken
Published: October 2009

Anthropologists tell us that over 500000000 years ago the seas swarmed with some type of marine life and that during the Devonian period of 350 0000 000 years ago we could find the first species of monk fish that is now in high demand on the fish market place and sought after in strange hostile waters by European fishermen. The sharks were introduced to the planet at about this time and until this day have had the reputation of being the ocean's most voracious predators.
UK Airspace Planning – The New ICAO Airspace Classification System
Authors: Walker W. J. V.
Published: October 2009

Since the advent of large-scale commercial aviation in the mid 1940s, a system of routes has been developed between airports serving the major conurbations of the world. To prevent collision between aircraft using these routes and off-route traffic, protection is provided to the routes and to the vicinity of airports by means of controlled airspace, airways (AWYS), control areas (CTAS) and control zones (CTRS). Zones commence at ground level and the base an area is at a defined altitude. Inside this controlled airspace certain rules apply which are more stringent than those applied outside, and all movements are subject to Air Traffic Control (ATC).
Interactions and Flexibility in the Orientation System of Migratory Birds
Authors: Able Kenneth P. , Able Mary A.
Published: October 2009

This paper, and the following 5 papers, were presented at the RIN93 Conference on “Orientation and Navigation - Birds, Humans and other Animals.” This took place in Oxford in April, and included some 40 papers. Copies of the complete Proceedings, priced £25 for RIN members and £35 for non-members, are available from the Director.
Navigation by Dead Reckoning and Local Cues
Authors: Etienne A. S. , Séguinot V.
Published: October 2009

According to comprehensive theories of navigation, animals navigate by using two complementary strategies: (1) dead reckoning informs the subject in a continuous manner on its actual location with respect to an Earthbound or absolute coordinate system; while (2) long-term associations between particular landmarks and specific locations allow the animal to find its way within a familiar environment. If the subject structures familiar space as a system of interconnected places – the so-called ‘cognitive map’ – it may know through dead reckoning where it is located on its map and relate its route-based expectations to the actually perceived scenario of local cues.
Recognition of Familiar Visual Landmarks in Homing Pigeons
Authors: Braithwaite V. A. , Guilford T. C.
Published: October 2009

It is now well established that homing pigeons (Columba livia) use a variety of mechanisms and cues to help them find their way home. It is far more difficult to determine the relative importance attached to such mechanisms and cues by pigeons during homing. As a step towards this quantitative stage in our understanding of homing behaviour we consider if cues contribute significantly to homing speed. In particular we attempt to assess the role of visual landmarks. Using pigeons released from familiar release sites, we demonstrate that birds home faster if they can view their surroundings from inside a Perspex box for 5 minutes prior to being released, compared to birds denied this view. Pigeons released from unfamiliar sites, however, do not show a similar improvement. We suggest that seeing familiar visual landmarks before release allows pigeons to become more certain of their current location with respect to home. Simply viewing the release site is not sufficient to produce a faster homing speed; the pigeons must be able to recognize that the release site is familiar.
Rediscovering Polynesian Navigation through Experimental Voyaging
Authors: Finney Ben
Published: October 2009

Over the last two decades, my colleagues and I have sailed a modern reconstruction of a Polynesian voyaging canoe some 40 000 nautical miles through Polynesian waters. This programme has been driven by two intertwined goals: one experimental – to test the sailing technology and navigational methods of the ancient Polynesians in order to resolve issues in Polynesian prehistory; and the other cultural – to enable contemporary Polynesians to relearn the means by which their ancestors found and settled their islands, and thereby gain a better sense of their uniquely maritime heritage and, ultimately, themselves. This paper focuses on the effort to rediscover how to navigate without instruments, and how that rediscovery is helping both to change scientific thinking about the colonization of Polynesia and to transform the selfimage of contemporary Polynesians.
Wide Area Differential GPS Field Study
Authors: Catchpole Ivan , Upton Peter , Sinclair Andrew , Nagle Jim
Published: October 2009

Inmarsat commissioned the field study to be carried out by Signal Computing Ltd. in association with the Royal Greenwich Observatory. The study aimed to identify the commercial suitability of Wide Area Differential GPS (WADGPS) corrections. The corrections provided to users will be relayed via Inmarsat-3 geostationary satellites and are required to be valid over the footprint of an entire Inmarsat ocean region (approximately one third of the Earth's surface).

The study has been conducted within the Inmarsat Atlantic Ocean Region East. Trials took place over a five-month period to achieve a representative set of data. Six widely-distributed collection sites were used to ensure that the maximum duration of satellite data were received and that a representative model for atmospheric effects was obtained. Analysis is restricted to the use of GPS carrier and phase data obtained using the C/A code transmitted by Block II satellites only.

This paper presents the analysis of data collected during a four-day trial period. The ability to determine the GPS satellite ephemeris (independent of GPS broadcast ephemeris), Klobuchar model parameters tailored to the oceanic region, and satellite clock corrections using GPS data obtained from this limited deployment of collection sites is addressed. The primary degradation effects on stand-alone GPS positioning of Selective Availability (SA) are corrected using WADGPS, resulting in a significant improvement in position accuracy.
Recent Technological Advances in the Control and Guidance of Ships
Authors: Witt N. A. J. , Sutton R. , Miller K. M.
Published: October 2009

Over the past seventy years many advances have been made in the field of ship control. Early developments by Sperry and Minorsky on proportional controllers have led to today's modern control systems which have interfacing capabilities with position fixing equipment.

This paper presents a brief historical summary of the methods employed in ship control from early proportional devices through the range of adaptive systems and concludes with details of a possible future control method known as intelligent control.

Intelligent control consists of three methodologies: expert, fuzzy and neural. An investigation and comparison of the methodologies will present possible future control strategies.
Use of GPS-Determined Attitude in Combination with Conventional Attitude Sensors
Authors: Matheisen Therese , Ørpen Ole
Published: October 2009

Use of multi antenna GPS equipment for determination of a vessel's attitude holds some promise for the development of accurate and inexpensive attitude systems. An application for such systems might be to provide very accurate roll information for multibeam echo sounders.

The present state-of-the-art GPS attitude systems cannot meet the required accuracy and update rate for such applications. GEOTEAM A/S has therefore developed a PC-based system which combines GPS-based attitude with roll and pitch information from a Vertical Reference Unit (VRU) and heading from a gyro compass.

In such a combined system, the long-term high accuracy of a GPS-based attitude system is combined with the short-term accuracy and fast update rate of conventional VRUS and gyro compasses in order to achieve a resulting performance that is better than any of the systems. In effect, the GPS attitude is used to calibrate the VRU and the gyro compass in real time.

During the past year extensive tests have been performed with a system using a Trimble VECTOR II GPS attitude system with a 1 metre baseline between the antennas, both on a van (with an inertial navigation system as reference) and on a vessel. During November and December 1993 further tests were made with an Ashtech 3DF attitude system with longer baselines (7·5 m). These tests were made on a vessel where the combined GPS/VRU attitude was fed into a multibeam echo sounder. These tests were performed in cooperation with Simrad Subsea A/S, the multibeam echo sounder EM 1000 manufacturer.
The GNSS Transponder – A Cost-Effective Worldwide GNSS-Based Civil Aviation CNS/ATM, ATC, ATN Data Link and Collision Avoidance System Concept
Authors: Nilsson Johnny , Lans Håkan
Published: October 2009

Sweden and some other countries are currently evaluating and verifying the potential impact of a newly developed, satellite-based GNSS transponder system on future CNS/ATM and ATN systems.

The concept provides the possibility to introduce a distributed, mobile, real-time data processing system, for all properly equipped users in the global civil aviation community being interacting members (air/air, air/ground and ground/ground).
Microwave Front End for True Ground Speed Measurements
Authors: Kehrbeck Jürgen , Heidrich Eberhardt , Wiesbeck Werner
Published: October 2009

A dual channel microwave Doppler-Sensor-Module for 24 GHz is presented. This front end is well suited for true ground speed and distance measurements in all kinds of automotive applications. The microwave components such as oscillator, mixer, antenna and their characteristics in the MIC are discussed. The influence of the antenna pattern and the road surface on the Doppler spectrum is treated in a 3D-field theoretical simulation. This simulation takes the antenna nearfield and the distributed scattering of the road into account.
Multiple Crossing Encounters
Authors: Lamb W. G. P. , Hunt J. M.
Published: October 2009

The risk of a close quarters situation arising when a vessel crosses a busy traffic lane, such as one of the separation lanes in operation in the vicinity of the Dover Strait, is usually assessed in terms of the number of encounters or domain infringements likely to occur if no avoidance action were taken. Such calculations, which are based on the theoretical encounter rate, do not normally take into account any enhancement of the risk which may be associated with the simultaneous interaction of a crossing vessel with more than one other ship.
A Voyage of Navigational Investigation
Authors: Richey Michael
Published: October 2009

During the summer months of 1994 the yacht Jester undertook a seagoing investigation into some of the navigational problems that would have confronted the Portuguese discoverers of the thirteenth and fourteenth centuries returning to mainland Portugal from the coasts of Africa and the Atlantic archipelagos. The investigation was made at the suggestion of the maritime historian D. W. Waters to illuminate one aspect of how astronomical navigation was first introduced at sea in the west.
The Uncertainty and Uncoordination of Mariners' Behaviour in Collision Avoidance at Sea
Authors: Zhao J. , Price W. G. , Wilson P. A. , Tan M.
Published: October 2009

It is well known that many collisions occur because one ship turns right whilst the other turns left when in close proximity to one another. Little is known as to why this occurs and, although some simulation models have been established using entropy theory, the problem remains unsolved.

In this paper, an assessment model for uncertainty is reviewed briefly. The concepts of uncertainty and uncoordination of mariners' behaviour in collision avoidance are discussed. A simulation model in conjunction with a DCPA (distance to the closest point of approach) decision-making model using fuzzy programming is introduced to discuss coordination.
Global Use of Satellite Technology for Air Traffic Management – A Trial of Automatic Dependent Surveillance
Authors: Selves G. E.
Published: October 2009

A developing theme of long-haul operations is the desire for non-stop services between large centres of population and business areas. The delivery of modern aircraft with such long-range capability is evidence of airline commercial objectives and plainly demands improvements to the way in which air traffic is managed. There is now an opportunity to change radically the way in which over-flights are managed and operated. It is imperative to increase capacity in step with demand as it is the limitation in capacity that is fast limiting an expansion of the business.
Principles of JTIDS Relative Navigation
Authors: Ranger J. F. O.
Published: October 2009

This paper describes one of the key features of the JTIDS/Link 16 tactical data-link, namely its relative navigation facility. A brief overview of the general features of the JTIDS system is given to provide the necessary background to the navigation aspects, and some mention is made of the message-exchange facilities. The main part of the paper describes how the JTIDS system provides the capability to perform accurate navigation, and discusses the basic principles of its operation. Some applications of the navigation function which enhance operational effectiveness are then described. The following topics are covered:

(ii) JTIDS Architecture

(i) Definition of JTIDS/Link 16

(iii) Principles of Relative Navigation

(iv) Source Selection

(v) The Kalman Filter

(vi) Time Synchronization

(vii) The Use of Relative Navigation

(viii) The Relative Grid
On The Vertical Speeds Of Airways Traffic
Authors: Magill S. A. N.
Published: October 2009

Knowledge of the statistics of aircraft vertical speeds is important both for the construction of realistic traffic simulators and for the development of trajectory prediction tools for use in future air traffic control (ATC) systems. This paper reports on the analysis of radar data recordings for nearly 10000 civil flights on airways. Results are presented for the means and spreads of vertical speeds as functions of altitude. Evidence is presented that roughly half of the observed spreads arise from fluctuations within each aircraft's trajectory, as opposed to variation from one aircraft to another. A simple procedure is proposed for simulating vertical speed data which has statistics similar to those obtained from the radar recordings. Some consequences of the results for the development of trajectory prediction tools for use in future ATC systems are discussed. The results suggest that the provision of accurate trajectory prediction tools is not as straightforward as it might at first appear to be.
Requirements for Coordination and the Application of an Automatic Collision Avoidance System
Authors: Perkins Chris , Redfern Tony
Published: October 2009

This paper is concerned with the legislative change which would have to take place if an automatic collision avoidance system were to be implemented.

The principle of complementary action, and the role of coordination in achieving that action is considered. Current collision avoidance practice is discussed, noting the coordination attributes of the International Regulations for the Prevention of Collision at Sea, and the responsibility placed on the mariner by the regulations. The processing element of an automatic collision avoidance system is considered in the light of current judicial practice.

The paper concludes that the implementation of an automatic collision avoidance system is incompatible with the current collision regulations and the supporting judiciary. It is suggested that successful implementation will require the recognition of a discrete rule base.
How Will Route Guidance Information Affect Cognitive Maps?
Authors: Jackson P. G.
Published: October 2009

This paper considers the effect of receiving a secondary source of information upon ability to acquire and use spatial knowledge (i.e. the formation of a cognitive map). Participants watch videos of three journeys through an unfamiliar area. They then perform tasks measuring ability to integrate the routes into a cognitive map of the area. Subjects viewing the routes whilst hearing route guidance information performed consistently worse than those receiving no guidance. The presence of non-salient information, however, did not impair performance.

Existing studies highlighting differences between gender and age groups regarding spatial ability receive only partial support: the results suggest that ability to drive negates these effects. Female drivers perform as well as, if not better than, their male counterparts, and outperform male non-drivers. This same ‘driving’ effect was also evident in the over-55s group, with both male and female drivers performing significantly better than non-drivers in this age group. The results also show that driving ability enhances ability to cope with and use guidance information, suggesting that systems’ designers should make varying levels of spatial information available for less experienced drivers.
London Transport Countdown's Next Steps
Authors: Balogh Stephen
Published: October 2009

This paper and the following paper were presented at a meeting organized by the Institute's Land Navigation Group in October 1995. The meeting was on Loction Technology Applications in Public Transport. Copies of the proceedings can be obtained from the Director (£10 to Members, £15 to Non-Members).
Relationship Between Satellite Elevation and Precision of GPS Code Observations
Authors: Xiang Jin Xin , de Jong Cees D.
Published: October 2009

First, a brief description is given of an algorithm for the generation of carrier-adjusted differential corrections. Next, the relationship between satellite elevation and the precision of GPS code observations is investigated, on the basis of data collected by TurboRogue SNR-8000, Trimble 4000 SSE and Trimble 4000 SST receivers. It is concluded that the precision of code observations decreases with decreasing elevation, particularly at low elevation and that the relationship can quite well be modelled by an exponential function. For different types of receivers and different types of code observables, this relationship may not be the same.
Satellite Navigation: GPS Inadequacies: Comparative Study into Solutions for Civil Aviation
Authors: Durand J. -M.
Published: October 2009

The Global Positioning System (GPS) will be an extremely high-performance satellite-based navigation system which is expected to provide a sole means air navigation service for most aeronautical flight phases. It will be particularly suitable for ‘en route’, ‘terminal’ and ‘non-precision approach’ phases, thus providing substantial savings on aircraft operating costs.

However, GPS has three major disadvantages for civil aviation: (1) Insufficient system integrity, since satellites can transmit erroneous information for two hours before being repaired or neutralized. In such an event, the many simultaneous users of the satellite that has lost its integrity can derive false positions and remain unaware of the problem. (2) Availability constrained by the limited number of satellites. Users are then unable to obtain a position fix or else obtain a result with significantly degraded performance. (3) Deliberate spatio-temporal degradation (selective availability) of system performance, the characteristics of which are not fully known or defined.

Many solutions to these problems have been put forward. One concept uses the redundancy of the GPS system itself (receiver autonomous integrity monitoring). Another set of solutions is based on complementary information from autonomous navigation equipment (altimeter, clock, inertial system) or external navigation systems already available or being developed (Omega, Loran-C, GLONASS). A third type of solution is to implement a system by which to monitor the status of the GPS satellites and broadcast the information to users.

This paper reports on the different techniques put forward and uses different qualitative criteria (technical feasibility, cost, political independence, etc.) to assess their suitability for civil aviation applications. The comparison leads to the recommendation of a system to monitor the status of the GPS satellites and broadcast the information to users. The characteristics of such messages would be as similar as possible to those of GPS messages.
Differential Omega as a Worldwide Navigation Aid
Authors: Stratton A.
Published: October 2009

Navigation aids in use today have their origin in mainly military operational requirements for navigation accuracy, coverage and integrity. They have also been directed at the needs of air and sea operations.
Proposal for Low Cost Ocean Weather Routeing
Authors: de Wit C.
Published: October 2009

This paper presents a concept for selecting a fixed time ocean route via a prefixed grid of points. The ship is to sail with a fixed pitch propeller rotating at a constant rate N. The starting and arrival points A and B are given, as well as the starting and arrival times t0and t1. The criterion is to obtain a route with a minimal value of N. The method is designed for a discrete navigating system. Thus it can be seen as an application of Bellman's Dynamic Programming Theory1. The ship's speed is estimated with the use of a modern algorithm, based on a well founded and well tested hydrodynamic model.
Presidential Address: Navigation in Aerial Commerce
Authors: Williams J. E. D.
Published: October 2009

Whatever the word ‘navigation’ is taken to mean, it must, etymologically, be something one does to a ship. What a pity that the name ‘airship’ was given so early in the evolution of aviation to its dinosaurs! The modern airliner is truly a ship of the air. There was a move, half a century ago, to coin the word ‘avigation’ but, apart from the obvious retort that, if ‘navigation’ is of ships, ‘avigation’ is strictly for the birds, the term ‘air navigation’ had already been established by the International Convention on Air Navigation and the Air Navigation Acts by which Parliament legislates on aviation in general and its commercial application in particular.
The Helmsman as a Man–Machine Element
Authors: Sutton R. , Towill D. R.
Published: October 2009

In this paper the role of the helmsman in terms of man–machine systems theory, such as is frequently used in aerospace work is considered and the literature of the subject surveyed in so far as it relates to the control of seagoing vessels. Lieutenant-Commander Sutton is in the Control Engineering Department at the Royal Naval Engineering College, Plymouth, and Professor Towill is head of the Department of Mechanical Engineering at UWIST, Cardiff.
Quantification of Navigational Risk in European Waters
Authors: Glansdorp C. C. , Kemp J. F. , Goodwin E. M. , Tresfon R.
Published: October 2009

This paper attempts to explain the development of a method to quantify navigational risk within European waters as a part of the COST 301 project. The objective of this project, partly funded by the EEC and partly by the member countries and a few other European countries, is to increase marine safety and to prevent pollution in European (coastal) waters by shore based aids to navigations. The methodology of this study is explained. The analysis of the collected data regarding traffic and casualties is given. The probability of a collision and a stranding is determined.

The authors are all members of working group 2 of COST 301. Ir. Glansdorp and Captain Tresfon are from the Netherlands Maritime Research Institute, Dr Goodwin is Head of the Mathematics Department at the Polytechnic of North London and Professor Kemp is former Head of the School of Navigation at the City of London Polytechnic.
Civil Satellite Navigation and Location Systems
Authors: Blanchard W. F.
Published: October 2009

1. INTRODUCTION. The American Global Positioning System (GPS/Navstar) and the USSR's Glonass are superb demonstrations of high technology but we should not forget that they were designed and implemented for a very different set of circumstances from that of the civil surveyor and navigator. Many of their features are not required for civil purposes and it is perfectly possible to get excellent results for many civil applications without the vast expenditure that went into those systems. This paper describes some of the ways in which it is proposed that satellites, not necessarily launched for the purpose, might be, and are being, exploited for civil navigation and location.
A Theory of the Tactical Conflict Prediction of a Pair of Aircraft
Authors: Havel Karel , Husarčík Jaroslav
Published: October 2009

The objective of ground collision avoidance systems (GCAS) is to assure the separation of aircraft during flight operations, GCAS can be divided into tactical and strategic systems. The term tactical implies conflict prediction made after every radar scan and with approximately a one minute look ahead time. The aim of the study is to build up a mathematical model which uses only radar information and predicts potential conflicts within a fixed time, p, which may differ in different areas.
Knowledge-based Collision Avoidance
Authors: Coenen F. P. , Smeaton G. P. , Bole A. G.
Published: October 2009

This paper describes preliminary studies towards a navigational Knowledge-based System currently in progress within the School of Engineering and Technology Management at Liverpool Polytechnic.
A New Suncompass: Orientation Independent of Clock Time
Authors: de Rijk J. A. F.
Published: October 2009

In situations where the use of a magnetic compass has disadvantages, it is sometimes possible to use successfully a suncompass. All known suncompasses use the clock time. This paper introduces a method of orientation which does not use clock time and which surpasses the accuracy and usefulness of the Cole suncompass.
Electron heating and airglow emission due to lightning effects on the ionosphere
Authors: Vlasov Michael N. , Kelley Michael C.
Published: October 2009

This study is the first attempt to consider lightning effects on the F2 region. Although pulsed electric fields parallel to the geomagnetic field have been observed by every rocket flight over active thunderstorms at thermospheric heights, their existence remains controversial. Predicting the disturbance of ionospheric parameters induced by these electric fields may lead to verifying them using ground‐based ionospheric observations. This study is also important for understanding the kinetics of ionospheric plasma disturbed by pulsed parallel electric fields. These fields can accelerate electrons from pulse to pulse. If the pause between flashes is longer than τen, electrons are scattered by elastic collisions with neutrals and transformed into thermal electrons with a corresponding electron temperature enhancement. Inelastic collisions of electrons with neutrals will become more important with increased energy and, subsequently, the electron energy distribution (EED) can differ from a Maxwellian distribution. The vibrational excitation of N2 is extremely important as a source of inelastic collisions for energy ≥2 eV. This vibrational barrier can influence the EED. An electron kinetics model induced by pulsed parallel electric fields in ionospheric plasma is developed here. The accelerated and heated electrons can excite airglow in the F2 region. Excitation of red line emissions is most effective. Red line intensities during thunderstorms are predicted to be much higher than the background intensity. Our model also predicts a significant increase in electron temperature in the F2 region during a strong thunderstorm. Opportunities for observing the ionospheric effects of parallel electric fields induced by lightning are discussed.
Evaluating highly resolved paleoclimate records in the frequency domain for multidecadal‐scale climate variability
Authors: DeLong Kristine L. , Quinn Terrence M. , Mitchum Gary T. , Poore Richard Z.
Published: October 2009

Do the chronological methods used in the construction of paleoclimate records influence the results of the frequency analysis applied to them? We explore this phenomenon using the Dongge Cave speleothem record (U‐series chronology with variable time steps, Δt) and the El Malpais tree‐ring index (cross‐dating of ring‐width series). Interpolation of the Dongge Cave record to a constant Δt resulted in the suppression of periodicities (<20 years) altering the red noise model used for significance testing. Frequency analysis of temporal subsets of the El Malpais tree‐ring index revealed that concentrations of variance varied with the number of ring‐width series. Frequency analyses of these records identified significant periodicities, some common to both (∼25 and ∼69 years). Cross‐wavelet analysis, which examines periodicities in the time domain, revealed that coherency between these records occurs intermittently. We found the chronology methods can influence the ability of frequency analysis to detect periodicities and tests for coherency.
Direct connectivity between upstream and downstream promotes rapid response of lower coastal‐plain rivers to land‐use change
Authors: Mattheus Christopher R. , Rodriguez Antonio B. , McKee Brent A.
Published: October 2009

Low‐relief fluvial systems that originate in the lower coastal plain and discharge into estuaries are common along passive margins. These watersheds are thought to be disconnected from their termini by floodplains, which buffer the sediment‐routing system by sequestration. Here, we present a detailed study of the Newport River, a typical lower coastal‐plain system, which reveals high connectivity between watershed and delta. Connectivity is measured as the time lag between initiation of a silviculture operation, which increased landscape erosion, and when the sediment appeared at the bay‐head delta. The time lag, measured from aerial photographs and sedimentation rates calculated from 210Pb‐ and 137Cs‐activities in cores from the watershed and delta, is <3 years. Most lower coastal‐plain rivers are steeper and have less floodplain accommodation available for storage than their larger counterparts that originate landward of the fall line, which promotes higher connectivity between upstream and downstream.
Changes in Cerebral Arterial, Tissue and Venous Oxygenation with Evoked Neural Stimulation: Implications for Hemoglobin-Based Functional Neuroimaging
Authors: Vazquez Alberto L , Fukuda Mitsuhiro , Tasker Michelle L , Masamoto Kazuto , Kim Seong-Gi
Published: October 2009

Little is known regarding the changes in blood oxygen tension (PO2) with changes in brain function. This work aimed to measure the blood PO2 in surface arteries and veins as well as tissue with evoked somato-sensory stimulation in the anesthetized rat. Electrical stimulation of the forepaw induced average increases in blood flow of 44% as well as increases in the tissue PO2 of 28%. More importantly, increases in PO2 throughout pial arteries (resting diameters=59 to 129 μm) and pial veins (resting diameters=62 to 361 μm) were observed. The largest increases in vascular PO2 were observed in the small veins (from 33 to 40 mm Hg) and small arteries (from 78 to 88 mm Hg). The changes in oxygen saturation (SO2) were calculated and the largest increases were observed in small veins (Δ=+11%) while its increase in small arteries was small (Δ=+4%). The average diameter of arterial vessels was observed to increase by 4 to 6% while that of veins was not observed to change with evoked stimulation. These findings show that the increases in arterial PO2 contribute to the hyper-oxygenation of tissue and, mostly likely, also to the signal changes in hemoglobin-based functional imaging methods (e.g. BOLD fMRI).
Sepsis-Associated Encephalopathy: A Magnetic Resonance Imaging and Spectroscopy Study
Authors: Bozza Fernando A , Garteiser Philippe , Oliveira Marcus F , Doblas Sabrina , Cranford Rebecca , Saunders Debra , Jones Inna , Towner Rheal A , Castro-Faria-Neto Hugo C
Published: October 2009

Brain dysfunction is frequently observed in sepsis as a consequence of changes in cerebral structure and metabolism, resulting in worse outcome and reduced life-quality of surviving patients. However, the mechanisms of sepsis-associated encephalopathy development and a better characterization of this syndrome in vivo are lacking. Here, we used magnetic resonance imaging (MRI) techniques to assess brain morphology and metabolism in a murine sepsis model (cecal ligation and puncture, CLP). Sham-operated and CLP mice were subjected to a complete MRI session at baseline, 6 and 24 h after surgery. Accumulation of vasogenic edematic fluid at the base of the brain was observed in T2-weighted image at 6 and 24 h after CLP. Also, the water apparent diffusion coefficients in both hippocampus and cortex were decreased, suggesting a cytotoxic edema in brains of nonsurvival septic animals. Moreover, the N-acetylaspartate/choline ratio was reduced in brains of septic mice, indicating neuronal damage. In conclusion, noninvasive assessment by MRI allowed the identification of new aspects of brain damage in sepsis, including cytotoxic and vasogenic edema as well as neuronal damage. These findings highlight the potential applications of MRI techniques for the diagnostic and therapeutic studies in sepsis.
Cyclooxygenase-1 and -2 Differentially Modulate Lipopolysaccharide-Induced Blood–Brain Barrier Disruption through Matrix Metalloproteinase Activity
Authors: Aid Saba , Silva Afonso C , Candelario-Jalil Eduardo , Choi Sang-Ho , Rosenberg Gary A , Bosetti Francesca
Published: October 2009

Cyclooxygenases (COX) -1 and -2 are key regulators of innate immune responses. We recently demonstrated that the expression of proinflammatory cytokines and chemokines is reduced in COX-1 null (−/−), and increased in COX-2−/−mice compared with their respective wild type controls during lipopolysaccharide (LPS)-induced innate immune activation. As chemokines are involved in leukocyte recruitment into the inflamed brain, we hypothesized that COX-1 and COX-2 deletion will differentially modulate blood–brain barrier (BBB) permeability in response to LPS. In the present study, using quantitative magnetic resonance imaging, we found that LPS-induced BBB disruption was exacerbated in COX-2−/−versus COX-2+/+mice. In the hippocampus and cortex of LPS-treated mice, matrix metalloproteinase (MMP)-3 activity was significantly decreased in COX-1−/−mice, whereas in COX-2−/−mice the activity of both MMP-9 and MMP-3, known to mediate BBB breakdown, was increased. Brain mRNA expression of the leukocyte attracting chemokine Cxcl10, the intercellular interaction molecule Icam-1, the pan-leukocyte marker Cd45 was increased in COX-2−/−versus COX-2+/+mice, whereas Cxcl10 and Cd45 mRNA expression was decreased in COX-1−/−versus COX-1+/+mice after LPS. Altogether, these results indicate that COX-2 activity modulates MMP-9 and-3 activities and is necessary to maintain BBB integrity during toll-like receptor 4-dependent innate immune activation.
Evaluating experiential education through an intertidal ecology field trip.
Authors: Lowry Kate , Wilber Cynthia , Dirzo Rodolfo
Published: October 2009

Background/Question/Methods

Stanford SEEDS and the Jasper Ridge Biological Preserve have worked together with Redwood High School to implement an experiential ecology education program. The Redwood Environmental Academy of Leadership(REAL) is designed to bring underserved high school students out of the classroom and into the outdoors to create a unique and effective learning experience. Though the program focuses on riparian ecosystem restoration, the course curriculum is interdisciplinary and designed to inspire continuation high school students to attend college or pursue environmental careers. Through a SEEDS special grant, REAL students were taken to Fitzgerald Marine Reserve in Half Moon Bay, California, to learn about marine ecology and intertidal ecosystems at a minus tide. Redwood High School students were joined by their teachers and Stanford faculty and students to study the adaptations of intertidal organisms to their harsh environment.

Results/Conclusions

SEEDS and REAL were able to evaluate the success of the field trip by comparing the students’ knowledge of intertidal habitat, the nature of the ocean ecosystems, plants, animals, and reproduction both before and after the trip. This opportunity provides insight into the effectiveness of experiential education for the REAL program and recommendations for future ecology outreach programs.
Bone Grafts in Craniofacial Surgery
Authors: Elsalanty Mohammed E. , Genecov David G.
Published: October 2009

Reconstruction of cranial and maxillofacial defects is a challenging task. The standard reconstruction method has been bone grafting. In this review, we shall describe the biological principles of bone graft healing, as pertinent to craniofacial reconstruction. Different types and sources of bone grafts will be discussed, as well as new methods of bone defect reconstruction.
Medial Wall Fracture: An Update
Authors: Thiagarajah Christopher , Kersten Robert C.
Published: October 2009

This article is a review of the literature and update for management of medial orbital wall fractures. A retrospective review of the literature was performed via PubMed to review the diagnosis and management of medial wall orbital fractures. Medial wall orbital fractures though commonly accompanying orbital floor fractures can also occur alone. There are two primary theories explaining the pathophysiology of medial wall fractures: the hydraulic theory and buckling theory. Most fractures do not require treatment. “White-eyed” trapdoor fractures necessitate immediate surgery to reduce the risk of muscle fibrosis. Trapdoor fractures are more common in the pediatric population. The vast majority of nondisplaced fractures without entrapment do not require surgery. Evaluating patients with medial wall fractures requires evaluation of muscle motility and relative enophthalmos. Patients with entrapped muscles require immediate treatment to prevent permanent injury to the muscle.
Chin IX: Unusual Soft Tissue Problems of the Lower Face
Authors: Flores Roberto L. , Zide Barry M.
Published: October 2009

When the editor asked me to write something related to the chin, I (B.M.Z.) told him I would like to concentrate on the soft tissue of the perioral and chin region, something previously not presented before in this Journal specifically or anywhere. Dr. Flores and I have chosen certain soft tissue cases of the lower face, each of which presents certain dilemmas. The reconstructive methods in each case are unique, previously not shown, and represent salvage from prior failures. Case 1 shows how an interior Abbe flap can be used for ipsilateral lip reconstruction. Case 2 shows how a large upper lateral lip elemental loss can be regained from cheek and not the lower lip. Cases 3 and 4 show how to regain proper white roll bulge and symmetry by overcorrection, then exact adjustment in a second stage. Case 5 shows how a failed chin/lip reconstruction can be salvaged to regain sulcus height and aesthetic unit reconstruction. Each case depicts unique reconstructive designs to produce an aesthetic final result.
Review of Bone Substitutes
Authors: Pryor Landon S. , Gage Earl , Langevin Claude-Jean , Herrera Fernando , Breithaupt Andrew D. , Gordon Chad R. , Afifi Ahmed M. , Zins James E. , Meltzer Hal , Gosman Amanda , Cohen Steve R. , Holmes Ralph
Published: October 2009

Bone substitutes are being increasingly used in craniofacial surgery and craniomaxillofacial trauma. We will review the history of the biomaterials and describe the ideal characteristics of bone substitutes, with a specific emphasis on craniofacial reconstruction. Some of the most commonly used bone substitutes are discussed in more depth, such as calcium phosphate and hydroxyapatite ceramics and cements, bioactive glass, and polymer products. Areas of active research and future directions include tissue engineering, with an increasing emphasis on bioactivity of the implant.
Is Project Alignment – a Process Perspective
Authors: Jenkin Tracy A , Chan Yolande E
Published: October 2009

Information system (IS) project alignment has been defined as the degree to which an IS's project deliverables are consistent with the project's objectives, which are shaped by the organization's IS strategy. These objectives may change as the project unfolds, reflecting emergent opportunities, limitations, and strategy (Jenkin and Chan, 2005). The IS project alignment process refers to the sequence and flow of events that lead to project alignment and, thus, strategy execution. To develop an understanding of project alignment processes – how IS projects become aligned or misaligned – this study examines nine projects across two organizational settings to analyze the key events and processes of project alignment. By analyzing three different project patterns using different organizational metaphors, this study explains evidence contradicting widely held beliefs about project management. Rather than planning and process maturity, the results of this study highlight the importance of executing processes, change, learning, knowing in practice, and heedful interrelating between project team members to align final project deliverables. This research, based on an empirical study, contributes to both the IS alignment and project management literatures by further developing the emerging concept of project alignment to include a process view of how to achieve alignment of final project deliverables with IS project objectives and the IS strategy.
Photonic guiding structures in lithium niobate crystals produced by energetic ion beams
Authors: Chen Feng
Published: October 2009

A range of ion beam techniques have been used to fabricate a variety of photonic guiding structures in the well-known lithium niobate (LiNbO3 or LN) crystals that are of great importance in integrated photonics/optics. This paper reviews the up-to-date research progress of ion-beam-processed LiNbO3 photonic structures and reports on their fabrication, characterization, and applications. Ion beams are being used with this material in a wide range of techniques, as exemplified by the following examples. Ion beam milling/etching can remove the selected surface regions of LiNbO3 crystals via the sputtering effects. Ion implantation and swift ion irradiation can form optical waveguide structures by modifying the surface refractive indices of the LiNbO3 wafers. Crystal ion slicing has been used to obtain bulk-quality LiNbO3 single-crystalline thin films or membranes by exfoliating the implanted layer from the original substrate. Focused ion beams can either generate small structures of micron or submicron dimensions, to realize photonic bandgap crystals in LiNbO3, or directly write surface waveguides or other guiding devices in the crystal. Ion beam-enhanced etching has been extensively applied for micro- or nanostructuring of LiNbO3 surfaces. Methods developed to fabricate a range of photonic guiding structures in LiNbO3 are introduced. Modifications of LiNbO3 through the use of various energetic ion beams, including changes in refractive index and properties related to the photonic guiding structures as well as to the materials (i.e., electro-optic, nonlinear optic, luminescent, and photorefractive features), are overviewed in detail. The application of these LiNbO3 photonic guiding structures in both micro- and nanophotonics are briefly summarized.
Nonuniqueness of magnetic fields and energy derivatives in spin-polarized density functional theory
Authors: Gál T. , Ayers P. W. , De Proft F. , Geerlings P.
Published: October 2009

The effect of the recently uncovered nonuniqueness of the external magnetic field B(r⃑) corresponding to a given pair of density n(r⃑) and spin density ns(r⃑) on the derivative of the energy functional of spin-polarized density functional theory, and its implications for the definition of chemical reactivity descriptors, is examined. For ground states, the nonuniqueness of B(r⃑) implies the nondifferentiability of the energy functional Ev,B[n,ns] with respect to ns(r⃑). It is shown, on the other hand, that this nonuniqueness allows the existence of the one-sided derivatives of Ev,B[n,ns] with respect to ns(r⃑). Although the N-electron ground state can always be obtained from the minimization of Ev,B[n,ns] without any constraint on the spin number Ns=∫ns(r⃑)dr⃑, the Lagrange multiplier μs associated with the fixation of Ns does not vanish even for ground states. μs is identified as the left- or right-side derivative of the total energy with respect to Ns, which justifies the interpretation of μs as a (spin) chemical potential. This is relevant not only for the spin-polarized generalization of conceptual density functional theory, the spin chemical potential being one of the elementary reactivity descriptors, but also for the extension of the thermodynamical analogy of density functional theory for the spin-polarized case. For higher-order reactivity indices, B(r⃑)’s nonuniqueness has similar implications as for μs, leading to a split of the indices with respect to Ns into one-sided reactivity descriptors.
The transverse resistivity in S/C multifilament wires studied through ac susceptibility measurements
Authors: Fabbricatore P. , Farinon S. , Incardone S. , Gambardella U. , Saggese A. , Volpini G.
Published: October 2009

In this paper we discuss an experimental method based on the ac susceptibility for measuring the effective transverse resistivity in multifilament NbTi wires designed for low loss applications. Short samples of wire are involved in the measurements, with lengths comparable with the twist pitch. The measured values of the transverse resistivity are compared to expectations coming from a model based on a numerical approach.
First-principles calculations of adsorption and dehydrogenation of trans-2-butene molecule on Pd(110) surface
Authors: Fu Qiang , Yang Jinlong , Luo Yi
Published: October 2009

Adsorption and dehydrogenation processes of trans-2-butene molecule on the Pd(110) surface have been studied by density functional theory calculations. Different adsorption configurations of the reactant, the dehydrogenated product, and the most favorable reaction pathway have been determined. The calculated energy barrier agrees well with the value deduced from experiments. It is found that the reactant molecule must undergo a rotation before the C–H bond cleavage, and surface Pd atoms are involved in the dehydrogenation reaction through the formation of the Pd–C–H three-membered metallacycle. Our calculations have not only provided reliable interpretation for various experimental observations but also shed more light on the dynamics of the reaction processes.