bluuebunny/crossref_metadata_2025 huggingface dataset:
On the minimum hybrid rank of a graph relative to a partition of its edges and its application to electrical network analysis
Authors: Narayanan H.
Published: July 2007

We consider the following problem in this paper: given a partition of the set of edges of a graph such that the subgraphs on the blocks of the partition are connected, what is the minimum number of node fission (splitting a node into two) and node fusion (coalescing two nodes) operations that will destroy all circuits containing edges from more than one block of the partition? This problem can be seen to be a generalization of the problem of determining the minimum hybrid rank of a graph. We may therefore regard this minimum number as the minimum hybrid rank of the graph relative to a specified partition of the edge set of the graph. We give an efficient algorithm for the construction of a minimum length sequence of such operations. Our solution can be applied to the problem of analysing networks after first decomposing them into subnetworks‐the equations of the network can be displayed in a bordered block diagonal form where the blocks along the diagonal correspond to the subnetworks and the thickness of the border corresponds to the minimum hybrid rank relative to the partition of the sets of edges of the network into the sets of edges of the subnetworks.
A fast linear programming approach to the design of 1D IIR digital filters
Authors: Papamarkos N. , Vachtsevanos G.
Published: July 2007

A general method is proposed for the design of optimal 1D IIR digital filters via linear programming. the method is based upon the formulation of an appropriate linear problem which assures satisfactory approximation error for the filter's magnitude frequency response. the linear problem does not require differential correction methods or other iterative techniques for its solution, thus resulting in a computationally efficient algorithm. Analytical examples are presented to illustrate the efficiency of the method for the design of stable 1D recursive digital filters.
On a family of new two‐op‐amp switched‐capacitor biquads for high‐frequency applications
Authors: Mulawka J. J. , Konczykowska A. D. , Bon M. L.
Published: July 2007

This paper presents three novel biquads derived by applying the concept of so‐called basic elements for switched‐capacitor (SC) circuits. These biquads are without continuous feedback and comprise two op‐amps. They were derived assuming a transfer function denominator of the same form as the Fleischer‐Laker type E circuit. It is shown that by a simple modification of the switching arrangement, i.e. by changing the type of the basic SC element, the effect of the amplifier finite gain on the performance of SC filters can be significantly reduced. the efficiency of this approach has been established by extensive simulation studies using the dedicated symbolic analysis program SCYMBAL. Design equations and comparison with already known biquads of this type are presented. Examples are provided to demonstrate that the proposed circuits require a low total capacitance while finite‐gain effects are considerably reduced.
Boundary surfaces in sequential circuits
Authors: Špány V. , Plvka L.
Published: July 2007

One of the most important tasks in the analysis of a non‐linear system is lo determine its global behaviour and, in particular, to delineate the domains of attraction for asymptotically stable solutions. Stable manifolds often act as boundary surfaces between such domains in the state space.

In this paper the morphology of boundary surfaces is studied in a single member of Chua's circuit family, although the techniques used apply equally well to many other non‐linear circuits. On the way, an answer is given to a former question of Matsumoto et al. concerning boundary surfaces in a chaotic circuit.

Dynamical properties of a sequential circuit can be investigated by means of switching between the system's attractors, and boundary surfaces play a crucial role in the process of switching. As an application of the boundary surface techniques, dynamical properties of two models for ternary logic are presented and analysed.
Transformerless synthesis of transistor and thyristor switching RLC 1‐ports
Authors: Kropacz W. S. , Mikolajuk K. , Tobola A.
Published: July 2007

As an extension of the synthesis method developed in a previous paper, the transformerless synthesis of reciprocal switched 1‐ports is presented in this paper. the transformerless structures of resistance switching n‐ports described by impedance, admittance or hybrid matrices have been proposed. These structures enable the synthesis of dynamical switching RC, RL and RLC 1‐ports. Using the state variables method, the realizability conditions and identification formulae for constant and sinusoidal input functions have been derived. Three numerical examples illustrate the developed methods. the present theory can be applied to create new thyristor and transistor arrangements, particularly compensators and auxiliary switching LC circuits facilitating the commutation of thyristors and transistors.
A new approach for automatic fault diagnosis in analogue circuits
Authors: Hatzopoulos A. A. , Kontoleon J. M.
Published: July 2007

In this paper the problem of fault diagnosis in analogue circuits is addressed by a method which can be regarded as an artificial intelligence approach. the topology of the circuit under test along with the nominal element values, the necessary element models and their possible failure modes are the basic tools used in the procedure. Fault location is accomplished using appropriate DC node voltage measurements under certain DC excitations on the nominal circuit and the faulty one. the detection of signal faults which have DC effects is the goal of the method; cases of faults with non‐DC effects are also examined. Demonstrative examples are given to show the applicability of the method on passive and active analogue circuits.
Geometric approach to VLSI layout compaction
Authors: Xiong Xiao‐Ming , Kuh Ernest S.
Published: July 2007

We present a new geometric approach to VLSI layout compaction in this paper. In contrast to existing compaction algorithms, we rely on the geometric method and bypass both compaction grids and constraint graphs during the entire compaction process.

A systematic and efficient way is introduced to enumerate all possible jogs. For the given layout topology we prove that the geometric algorithm yields the minimum‐area layout in one‐dimensional compaction with automatic jog insertion. In the final output, only necessary jogs are inserted and the total wire length is minimized as a secondary goal. Furthermore, the integration of local compaction tools into a layout CAD system and the practical extensions of our algorithm are addressed.
Upper bound on the number of equivalent oscillator‐notch filter circuits: A group theoretic approach
Authors: Raadhakrishnan P. , Rao B. V.
Published: July 2007

It is shown that the problem of synthesizing RC oscillators and notch filters can be reduced to a group theoretic problem of finding isomorphisms. the required group is identified as the Klein group. From this it is also shown that there is a sharp upper bound on the number of new circuits that can be generated from the knowledge of a parent circuit. This bound is independent of the number of branches and internal nodes.
An efficient algorithm for analysis of piecewise‐linear resistive circuits: Driving‐point and transfer characteristic plots
Authors: Huang Qiu , Liu Ruey‐Wen
Published: July 2007

A new efficient algorithm is presented for finding all driving‐point characteristic (DP) and transfer characteristic (TC) plots for a broad class of piecewise‐linear (PWL) resistive circuits without the need for initial points for each solution branch. the piecewise‐linear circuits to be considered need not be continuous nor need their linear regions be divided by grid‐like hyperplanes. the computation of the new algorithm is based on zone‐by‐zone instead of the conventional region‐by‐region. Since each zone includes several regions and only one matrix inversion is needed for each zone, a significant reduction of computation can be achieved. Furthermore, the computational complexity for finding all solution branches, i.e. finding the DC operating points over the entire range of input values u, is no more than for finding all DC operating points over a single value u as far as the number of matrices needed to be inverted is concerned.
A one‐dimensional model of dynamics for a class of third‐order systems
Authors: Ogorzalek Maciej J.
Published: July 2007

For a class of third‐order non‐linear systems whose dynamics is governed by a differential equation of the form

equation image

we propose a one‐dimensional model reflecting the dynamic properties of the original system. Construction of this model map has been based on analysis of the trajectory behaviour in the original third‐order system. Properties of the model map have been investigated. Experiments have proved that the proposed one‐dimensional map, termed a deformed spiral map, reproduces the qualitative behaviour (e.g. bifurcation sequences) of the original system with very good accuracy.
City hall looks to the colleges
Authors: Seidman Harold
Published: July 2007

After five years trial New York City's unique experiment in public service training has more than justified efforts on the part of students, college faculties, city offficials.
Half century—half measure
Authors: Atkins Richard A.
Published: July 2007

With state help Metropolitan Boston made good start toward solution of its regional problems, but more recent proposals for either comprehensive or piecemeal measures have failed.
Model county faces problems
Authors: Houseman Julian Cory
Published: July 2007

Annexation of some of its richest tax‐yielding territory by Richmond brings Henrico fresh difficulties to solve; but eficiency of manager plan may bear fruit in the city.
What price city government?
Authors: Wyckoff V. J.
Published: July 2007

Growing dependence by cities on state and federal aid seen during postwar years because of apparently static or even declining revenues from purely municipal sources.
Wanted: New type politician
Authors: Mosher William E.
Published: July 2007

We (the Athrrians) are the only people to regard the man wha takes no interest in politics, not as careless, but as useless. Pericles.
Utilities need regional basis
Authors: Bauer John
Published: July 2007

Strains of war emphasize importance of planning service throughout metropolitan areas; many cities cooperate in currem study of methods, organization, trends, future needs.
Boy legislature plan spreading
Authors: Weidner Edward W.
Published: July 2007

Observers from other states study program developed by YMCA in New Jersey with Princeton's aid; see vehicle for youth training for active participntion in civic aflairs.
Intercity cooperation increases
Authors: Pope James P.
Published: July 2007

Tennessee Valley communities, stimulated by great power development, progress rapidly in joint action and self‐improvement efforts; urban‐rural understanding improved.
Rising tide of civic progress
Authors: Woodruff Clinton Rogers
Published: July 2007

The American people were led by the early “reformers” to a realization that bettering city government was perhaps the most important problem at the close of the 19th century.
Model laws as aid to progress
Authors: Dodds Harold W.
Published: July 2007

It would be dificult to measure the full extent of the influence of the model lows on governmental efficiency, economy and integrity. Their impact has been great.
What of the next 50 years?
Authors: Seasongood Murray
Published: July 2007

There will be continuing need of an unselfish, intelligent and impartial organization such as the League if local government and American democracy are to function well.
By their own bootstraps, III
Authors: Tugman William M.
Published: July 2007

Eugene and Lane County citizens break a century‐old habit and take the hard road to freedom from debt in schools, city and county; way cleared for sound postwar planning.
Acupuncture Affects Regional Blood Flow in Various Organs
Authors: Uchida Sae , Hotta Harumi
Published: July 2007

In this review, our recent studies using anesthetized animals concerning the neural mechanisms of vasodilative effect of acupuncture‐like stimulation in various organs are briefly summarized. Responses of cortical cerebral blood flow and uterine blood flow are characterized as non‐segmental and segmental reflexes. Among acupuncture‐like stimuli delivered to five different segmental areas of the body; afferent inputs to the brain stem (face) and to the spinal cord at the cervical (forepaw), thoracic (chest or abdomen), lumbar (hindpaw) and sacral (perineum) levels, cortical cerebral blood flow was increased by stimuli to face, forepaw and hindpaw. The afferent pathway of the responses is composed of somatic groups III and IV afferent nerves and whose efferent nerve pathway includes intrinsic cholinergic vasodilators originating in the basal forebrain. Uterine blood flow was increased by cutaneous stimulation of the hindpaw and perineal area, with perineal predominance. The afferent pathway of the response is composed of somatic group II, III and IV afferent nerves and the efferent nerve pathway includes the pelvic parasympathetic cholinergic vasodilator nerves. Furthermore, we briefly summarize vasodilative regulation of skeletal muscle blood flow via a calcitonin gene‐related peptide (CGRP) induced by antidromic activation of group IV somatic afferent nerves. These findings in healthy but anesthetized animals may be applicable to understanding the neural mechanisms improving blood flow in various organs following clinical acupuncture.
Apitherapy: Usage and Experience in German Beekeepers
Authors: Hellner Markus , Winter Daniel , von Georgi Richard , Münstedt Karsten
Published: July 2007

This study aimed to investigate the practice of apitherapy ‐ using bee products such as honey, pollen, propolis, royal jelly and bee venom to prevent or treat illness and promote healing ‐ among German beekeepers and to evaluate their experiences with these therapies. A questionnaire incorporating two instruments on beekeepers’ physical and mental health and working practice was included in three German beekeeping journals and readers were asked to complete it. The instrument included questions on the use of apitherapy. Simple descriptive methods, bivariate correlation, cross‐tabulation and one‐way ANOVA were used to analyze the data. Altogether 1059 completed questionnaires were received. The beekeepers reported the most effective and favorable therapeutic effects with honey, followed by propolis, pollen and royal jelly. The factors associated with successful experiences were: age, number of hives tended, health consciousness, positive experiences with one product and self‐administration of treatment. Beekeepers were asked for which condition they would employ propolis and pollen. They reported that they used propolis most frequently to treat colds, wounds and burns, sore throats, gum disorders and also as a general prophylactic, while pollen was most commonly used as a general prophylactic and, less frequently, in treating prostate diseases. No adverse experiences were reported. The potential benefit of bee products is supported by the positive experiences of a large group of beekeepers who use some of these products to treat a wide range of conditions. The indications and treatments given here may be important in selecting bee products and designing future trials.
Chinese Herbal Medicine for Dysfunctional Uterine Bleeding: A Meta‐Analysis
Authors: Tu Xiang , Huang Gaomin , Tan Shengkui
Published: July 2007

We conducted a systematic review to evaluate the efficacy and safety of Chinese herbal medicine (CHM) for dysfunctional uterine bleeding (DUB) by performing a meta‐analysis. Randomized controlled trials (RCTs) or quasi‐RCTs comparing CHM vs no treatment, placebo, conventional western medicine (CWM), or general non‐specific surgical treatment for DUB were identified by electronic and manual searches. Trials of CHM treatments with CWM treatments were compared with CWM treatments alone. Jadad scale and allocation concealment were used to assess the quality of included studies. Four RCTs or quasi‐RCTs involving 525 patients were included. The methodological quality was poor in all trials except one trial. No serious adverse events were reported in the included studies. With the lack of trials comparing CHM with no treatment or placebo, it is impossible to accurately evaluate the efficacy of CHM. However, CHM in these studies seem to show an encouraging comparative effectiveness with CWM. More RCTs with a higher quality are required.
Acupuncture on the Blood Flow of Various Organs Measured Simultaneously by Colored Microspheres in Rats
Authors: Tsuru Hiroyuki , Kawakita Kenji
Published: July 2007

We examined how acupuncture affected the blood flow of muscle, kidney, stomach, small intestine, brain, lung, heart, spleen and liver. Wistar rats anesthetized with urethane (n = 27) were allocated into the control (n = 10), ST‐7 (Hsia‐Kuan, n = 10) and LI‐4 (Hoku, n = 7) groups. To measure organ blood flow, colored microspheres (CMS) were injected through a catheter positioned in the left ventricle and blood samples were drawn from the femoral artery. Yellow CMS (3.6–4.2 × 105) and blue CMS (6.0–6.9 × 105) were injected at intervals of about 30 min. An acupuncture needle (φ 340 μm) was inserted into the left ST‐7 point (left masseter muscle) or the right LI‐4 point after the first sampling and left for about 30 min (10 twists at 1 Hz, 2‐min intervals). The mean blood flow of nine organs varied widely from 4.03 to 0.20 (ml/min/g). Acupuncture to the ST‐7 produced significant changes of the blood flow (percentage change from baseline) in the muscle, kidney, brain and heart (P < 0.05, versus control), but those of LI‐4 were not significant. The blood flow of the left masseter muscle after acupuncture to ST‐7 (left masseter muscle) tended to increase (P = 0.08). Changes in blood pressure during the experimental periods were almost similar among these three groups. Acupuncture stimulation increases the blood flow of several organs by modulating the central circulatory systems, and the effects differed with sites of stimulation.
Yoga Reduces Symptoms of Distress in Tsunami Survivors in the Andaman Islands
Authors: Telles Shirley , Naveen K. V. , Dash Manoj
Published: July 2007

A month after the December 2004 tsunami the effect of a 1 week yoga program was evaluated on self rated fear, anxiety, sadness and disturbed sleep in 47 survivors in the Andaman Islands. Polygraph recordings of the heart rate, breath rate and skin resistance were also made. Among the 47 people, 31 were settlers from the mainland (i.e. India, ML group) and 16 were endogenous people (EP group). There was a significant decrease in self rated fear, anxiety, sadness and disturbed sleep in both groups, and in the heart and breath rate in the ML group, and in the breath rate alone in the EP group, following yoga (P < 0.05, t‐test). This suggests that yoga practice may be useful in the management of stress following a natural disaster in people with widely differing social, cultural and spiritual beliefs.
Compositional data analysis
Authors: Reyment Richard A.
Published: July 2007

Compositional data occur naturally in the geosciences — tables of chemical analyses, rock‐compositions, sedimentary proportions, pollen‐analytical tables, etc. The statistical analysis of such data requires special techniques and it is not possible to use standard methods of computing correlation coefficients and carry out multivariate statistical analyses without the risk of incurring grave mistakes. The special property of compositional data, to wit, the fact that the determinations on each specimen sum to a constant, means that the variables involved in the study occur in constrained space defined by the simplex, a restricted part of real space.
An Early Cretaceous fossil bird from Montsec Mountain (Lleida, Spain)
Authors: Lacasa‐Ruiz A.
Published: July 2007

From among fossil fauna and flora specimens discovered in the famous outcrop of lithographic limestone of Montsec Mountain (Lleida, Spain), from the Early Cretaceous, there is one specimen of a small incomplete bird skeleton. Only the bones of the left wing, the wish‐bone (furcula), feathers and some other fragmentary bones are preserved. It lacks the skull, backbone, pectoral region, pelvic girdle and hind legs.
Coesite in the Straumen kyanite‐eclogite pod, Norway
Authors: Smith David C. , Lappin Michael A.
Published: July 2007

The occurrence of coesite in the Straumen kyaniteeclogite pod in the Western Gneiss Region (WGR), Norway, is described. Although the microtextures of coesite, and of its partial or complete transformation into quartz, are similar to those described at the first coesite occurrence in Norway (the Grytting dolomite‐eclogite pod) there are some significant differences at this second locality. These include the host mineral of the SiO2 inclusions being garnet, instead of clinopyroxene, and also occasionally kyanite. An initial coesite—eclogite (sub)facies paragenesis was followed by a quartz—eclogite (sub)facies paragenesis which, in addition to rutile and dolomite or calcite, contains the highest number (7) of silicate phases known in any Norwegian eclogite: garnet, clinopyroxene, kyanite, quartz, phengite, zoisite and clinoamphibole. This second occurrence of definite coesite:

(i) consolidates the very high pressury estimates (about 30 kbar minimum) previously deduced for certain eclogite pods occurring in the WGR; and

(ii) justifies the recognition of the ‘Norwegian coesite—eclogite province’ constituted of a nappe (terrane) of about 30 kbar parageneses now residing in the WGR.
Percolation in the Crust
Authors: Gavrilenko P. , Gueguen Y.
Published: July 2007

Considering the Earth's Crust as a heterogeneous medium, we show here that the general features of the seismic, electrical, and mechanical properties of the Crust can be conveniently described with a unified model derived from percolation theory. The basic assumption is that fracture density is a variable parameter which decreases with depth and as a result there exists a critical threshold below which fractures are only connected within finite clusters. This threshold corresponds to a critical fracture density and to a critical depth. Fluids circulate through a connected network of fractures down to the critical depth Zc. Below Zc, anisotropic fracture clusters result in seismic reflectors and high electrical conductivity. Earthquakes are restricted to depths shallower than Zc, where friction controls the mechanical resistance to fluid infiltrated pre‐existing fractures.
Archosaurian reptiles with Gondwanan affinities in the Upper Cretaceous of Europe
Authors: Buffetaut Eric
Published: July 2007

The Late Cretaceous (mainly Campanian and Maastrichtian) non‐marine vertebrate faunas of Europe contain archosaurian reptiles which belong to groups otherwise known mainly or only from the southern ('Gondwanan') continents. They include titanosaurid sauropods, abelisaurid theropods, and trematochampsid crocodilians. The occurrence of these forms together with others of ‘Asiamerican’ affinities gives the Late Cretaceous vertebrate faunas of Europe a peculiar composition, which makes them clearly different from the well‐known faunas from western North America and Central Asia. The Gondwanan dinosaurs and crocodilians from Europe provide evidence of faunal interchange across the Tethys Sea during the Cretaceous, possibly via the Alboran plate, or the Apulian plate, which may have functioned as ‘stepping‐stones', especially during periods of low sea level.
Recent explosive volcanic episodes on the Island of Kos (Greece): associated hydrothermal parageneses and geothermal area of Volcania
Authors: Bardintzeff Jacques‐Marie , Dalabakis Pascalis , Traineau Hervé , Brousse Robert
Published: July 2007

Altered xenoliths in the 0.25–0.12 Myr non‐welded ignimbrite deposits of the Island of Kos (Greece) provide evidence for a hydrothermal convective system in the basement complex. The conjunction of a potential heat source, high‐temperature hydrothermal parageneses, permeable and porous bedded formations, continuing tectonic phenomena and successive fracturing and possible access by sea‐waters, argues for a favourable geothermal potential. The hydrothermal area of Volcania, where mineralized and sometimes degassing waters circulate, could be regarded as a zone of lateral leakage from the hydrothermal convective system, which developed above the cooling magma chamber.
Confidence bounds on risk assessments for underground nuclear waste repositories
Authors: Woo Gordon
Published: July 2007

The estimation of risk confidence bounds is an important element of a comprehensive probabilistic risk assessment for a radioactive waste repository. Normal distribution bounds may be used in the asymptotic limit of a very large number of Monte Carlo simulations, but sharp skewness of the risk distribution may severely retard the convergence process. The Tchebycheff bounds are parameter‐free and may be applied regardless of distribution, save for the finiteness of variance. These bounds may be generally applicable, but they are invariably very broad. Better parameter‐free bounds for mean risk are presented here, based on an inequality originally derived by Guttman.
GEO LOGIC
Authors: Browning Paul
Published: July 2007

Let me begin by outlining the role of this column. It is aimed at European geoscientists who use personal computers. Rather than duplicating what is already discussed in the hundreds of computer magazines that can be found at any newsagent, I will concentrate on those products and services that have a particular application in the Earth Sciences. This is not to say that only those products with a specific Earth Science application will be discussed. Instead, anything that a practising geoscientist might find useful will be a candidate for review; a software package for compiling reference lists in the many styles demanded by different journals would be an example. The column will devote itself to products for IBM‐PC and Mac users. I apologise in advance for the UK perspective offered in the first few articles; this reflects my ignorance of the European scene and the difficulties I have faced in overcoming it. I look forward to feedback from continental geoscientists who, I hope, will bring me up to date regarding the truly European picture.
TERRA abstracts
Authors: Muir‐Wood R.
Published: July 2007

If you are involved in organizing a meeting, conference or symposium on any aspect of the Earth Sciences, contact the TERRA Abstracts editorial office in Oxford at the earliest stage of your planning. TERRA Abstracts will organize the preparation of high quality supplements containing all the abstracts of your meeting. The headings (titles and authors’ names) for the abstracts will be typeset in a standard format and the whole supplement will be bound into a cover designed according to your requirements.

Included in the supplement and at no extra charge, will be two indexes—one for all the authors, the second for keywords.
Evidence for bacterial degradation of hydrocarbons in uranium deposits
Authors: Landais Patrick
Published: July 2007

The biodegradation of free hydrocarbons migrated in reservoir faaes has often been observed in petroleum exploration. This bacterial alteration is characterized by the progressive removal of different classes of hydrocarbons. One of the most important consequences of biodegradation is the reduction of sulphate, as noted in several Pb‐Zn deposits. Biodegradation of oils spatially associated with uranium deposits has also been observed in Lodeve (France), Grand Canyon (Arizona, USA), Temple Mountain (Utah, USA) and leads to the transformation of fluid oils into solid bitumens. Within this study emphasis has been laid on the relationships between the effects of biodegradation on organic matter (oxidation or aromatization) and the nature of aqueous solutions analysed in fluid inclusions trapped in authigenic minerals. Different mechanisms are proposed to explain the transformations of organic matter during biodegradation and their possible links with ore‐forming processes.
One‐dimensional modelling of episodic fracturing: a sensitivity study
Authors: Cao S. , Lerche I. , Lyon W. G.
Published: July 2007

Episodic fracturing is discussed in relation to both sedimentary deposition rates and lithology, as well as to pressure release criteria and vertical numerical grid sizes of a one‐dimensional fluid‐flow/ compaction model. It is shown that the evolution of episodic fracturing is a ruggedly stable pattern for fine‐scale gridding, and that a critical fracture pressure of around 0.8 of the lithologic overburden is suggested.
Low‐angle faults above and below a blueschist belt—Tinos Island, Cyclades, Greece
Authors: Avigad Dov , Garfunkel Zvi
Published: July 2007

New observations from the Island of Tinos, Greece, allow a better definition of the structural position of the Alpine (Eocene) blueschist belt exposed in the islands of the Aegean Sea. These blueschists, over a significant part of the Aegean sea, are delimited from below by a low‐angle thrust fault, while from above they are delimited by a low‐angle, normal‐type fault which omits a substantial crustal interval. Both underlying and overlying rocks were not affected by the high? metamorphism. The rapid uplift and exhumation of the high? rocks was therefore mainly the result of fault movements rather than erosion and whole‐crust uplifting. The low‐angle normal fault apparently had a major role in the uplift of the blueschists.
Vanadiferous minerals from the Nereus Deep, Red Sea
Authors: Jedwab Jacques , Blanc Gérard , Boulegue Jacques
Published: July 2007

The chemical analysis by EMPEDS of 140 samples in cores from six Red Sea troughs and basins has led to the discovery in the Nereus Deep of high vanadium concentrations (up to 1.3% V2O3) in several bulk samples, and to the isolation of a major magnetite phase. This vanado‐magnetite, remarkable for its high content of vanadium (mean = 1.45% V2O3) and its lack of titanium, is frequently zoned, the V‐content decreasing toward the outer zones. Oxides with up to 42% V2O3, have also been found. Since the origin of the magnetite is clearly authigenic, its high vanadium and low titanium concentrations are traced back to the differential hydrothermal leaching of Fe—Ti‐oxides which occur profusely in basic eruptive rock clasts, actually present in some of the overlying seams.
Fluidization pipes in volcaniclastic mass flows, Volcan Hudson, Southern Chile
Authors: Best James L.
Published: July 2007

The presence of fluidization pipes within pyroclastic sediments has been proposed as a criterion for differentiating these volcaniclastic deposits from those of epiclastic mass flows. Observations of pipe structures within low‐temperature epiclastic mudflows produced by the 1971 eruption of Volcan Hudson, Southern Chile, demonstrate that this assumption is invalid and that the presence of pipes may only be utilized to interpret the precise mechanics of the fluidization process itself.
In vitro growth of iron sulphide chimneys: possible culture chambers for origin‐of‐life experiments
Authors: Russell Michael J. , Hall Allan J. , Turner Dugald
Published: July 2007

Iron monosulphide globules and tubes grown in the laboratory have similar morphologies to the fossil pyrite botryoids and chimneys found in the Silvermines exhalative sedimentary ore‐body of Carboniferous age in Ireland. We envisage analogous fine structures growing at hot springs (100–200°C) in the earliest oceans as having provided the culture chambers and flow reactors for life to originate by phosphorylation and growth of organic molecules on the iron sulphide surfaces. Such sulphide structures grown in the laboratory could be used in origin‐of‐life experiments.
Organic sulphur fixation in freshwater lake sediments and the implication for US ratios
Authors: Losher A.J. , Kelts K.R.
Published: July 2007

A comparative analysis of two sediment cores from perialpine lakes (L. Zürich and L. Geneva) helped to clarify pathways of sulphur fixation in freshwater sediments. Despite greater than three‐fold differences in lake water sulphate concentration equal amounts of sulphur are fixed in the sediments. The maximum sedimentary sulphur concentrations attain 1% (dry weight) which is similar to the sulphur content of modem, near‐shore marine sediments. This is also expressed in low Corg/Stot ratios which range from 2.5–8.

An analysis of the sulphur pools showed that organic sulphur compounds are the main components of the sedimentary sulphur, accounting for ˜ 80% and ˜ 60% of the total sulphur in Lakes Zürich and Geneva, respectively. The largest single sulphur pool is the sulphate‐esters, which comprise 40–60% of the total sedimentary sulphur. Substantial amounts of the organic sulphur compounds must be formed within the sediment by boundary‐layer microbial communities at the oxic‐anoxic transition zone. This possibly suggests rapid recycling of sulphur in suboxic zones. Because of low concentration of SO24‐‐ in the watermass, the zone of sulphate reduction is very thin. This coupled with the mobility of some sulphide oxidizing microbial colonies (e.g. Beggiutoa) potentially results in an almost complete recycling of the sulphur pool near the sediment‐water interface. Reduced sulphur caught in this cycling process is unavailable for sedimentary pyrite formation. The Corg/Spyriteratios for these sediments are thus high. If organically bound sulphur is not completely transformed into pyrite during late diagenesis, the Corg/ Spyrite ratio can serve as a sensitive indicator for the salinities of anaent depositional environments.
Low‐latitude anhydrite from the Red Sea coast: palaeoclimaticand palaeohydrological implications
Authors: Gunatilaka A.
Published: July 2007

Recent supratidal anhydrite (CaS04) is reportedly confined to a latitudinal range of ˜ 24–30°N. Because of this apparent constraint, it is problematical to relate known distributions of ancient deposits to palaeomagnetically determined latitudes. Recent work on the Red Sea coast of the Sudan shows that anhydrite is present south of 18°N and possibly down to 15°N latitude. In Arabia and North America ancient sabkha anhydrites occupy near‐equatorial positions, which imply climatic belts within subtropical high‐pressure cells. There is no reason why anhydrite should not occur at lower latitudes, provided the depositional area is within an effective rain‐shadow where evaporation far exceeds rainfall (as in the Red Sea region).
Three recent larger earthquakes offshore Norway
Authors: Hansen Roger A. , Bungum Hilmar , Alsaker Alfred
Published: July 2007

Three earthquakes of magnitude around 5 occurred offshore western Norway on 5th February, 1986, on 8th August, 1988, and on 23rd January, 1989. These earthquakes, representing the highest seismic activity level in this area for at least 30 years, were all felt by people over most of southern and central Norway. Focal‐mechanism solutions for these earthquakes indicate thrust faulting along N‐S to NNE‐SSW striking fault planes, in response to NW‐SE compressional stress, most probably of plate tectonic origin.

A number of high‐quality digital recordings of the ground motions at various distances from these and other recent earthquakes in Norway have shown that source spectral as well as wave attenuation characteristics in this area are reasonably consistent with what has been derived from other intraplate areas.
Geological events in the bible
Authors: Bentor Y.K.
Published: July 2007

The books of the bible contain numerous, frequently very exact, descriptions of geological events. Some of these are discussed here: earthquakes and their accompanying landslides (the crossing of the River Jordan), seiches and tsunamis (the flood), flooding (Sodom and Gomorrah), faulting, burning gas seepages (the Burning Bush) and volcanism (Mount Sinai). These geological events appear in the biblical text mainly for artistic reasons; they serve as a suitable background to dramatize the biblical account; they create a supernatural atmosphere for the main stories, but the time and place at which they occurred are of no importance to the narrator and might be shifted freely.
On the origin of copper mineralization in the Kupferschiefer: a suIphur isotope study*
Authors: Sawlowicz Zbigniew
Published: July 2007

Sulphur isotopic compositions of copper and iron sulphides (dispersed and vein mineralization) from the Polish part of the Kupferschiefer were determined and compared with data from the literature. Most of the δ34S values of sulphides range from about ‐40 to ‐25%, indicating sulphide precipitation during bacterial sulphate reduction in an open system which gradually chanes into a closed system. Sulphides from veins are usually enriched in 34S compared to finely dispersed mineralization and were probably formed in a more closed system. Copper sulphides are generally a few permil heavier than pyrite. Coupled with detailed microscopical observations the isotope data suggest that the mineralization is either syngenetic or early diagenetic.
Late Cretaceous evolution of the Judean Mountains as indicated by ostracodes
Authors: Flexer A. , Gilat A. , Hirsch F. , Honigstein A. , Rosenfeld A. , Rueffer T.
Published: July 2007

The Judean Mountains’ anticlinorium, Israel, a part of the Syrian Arc fold system, underwent several phases of compressional folding, uplift and faulting in post‐Turonian through Quaternary times. This study emphasizes the earliest tectonic phase of earIy Late Coniacian age. Ostracode biozonation clearly indicates the duration and extension of Senonian sedimentation and timing of onlap over the evolving Judean Mountains’ structure.
Microdistribution of boron: particle‐track images from samples of a Caledonian igneous complex
Authors: Sauerer A. , Troll G. , Matthies D.
Published: July 2007

7Li recoil tracks in LexanR formed as a product of irradiation with thermal neutrons give an image of in sifu‐microdistribution of boron in dioritic to granitic rocks of the Caledonian Ballachulish zoned complex and in a carbonate rock from its contact aureole. The images exhibit a polyphase incorporation of boron into primary and secondary minerals. The boron microdistribution is inhomogeneous. Isomorphous incorporation of boron into pyroxene and plagioclase during the main stage of crystallization cannot be established, because the boron distribution is blurred by secondary alteration. In contrast to the intracrystalline feature, the crystal interfaces are enriched in boron. Increased concentrations are also disclosed by overgrowths of primary crystals, exsolution lamellae in alkali feldspar and alteration rims of clinopyroxene. The highest amounts of boron in a siliceous dolomite marble of the contact aureole are found in the alteration products of olivine.
Occurrence patterns of large earthquakes in the seismic zones along the Hellenic Arc
Authors: Papadimitriou E.E.
Published: July 2007

Occurrence patterns of large shallow and intermediate depth earthquakes in the seismic zones along the Hellenic Arc have been investigated. It is shown that throughout this active region the earthquakes tend to occur in a rather systematic manner. At each time‐period earthquakes occur within a discrete activated segment of the arc. These occurrence patterns are considered to offer an insight into identifying where large earthquakes are expected to occur in the future.
Periodicities of CaCO3 cycles in the Pliocene of Sicily: discrepancies with the quasi‐periods of the Earth's orbital cycles?
Authors: Hilgen F.J. , Langereis C.G.
Published: July 2007

A high‐resolution CaCO3 record in combination with a detailed magnetostratigraphy is presented for the rhythmically bedded marly sequence of the Pliocene Trubi Formation on Sicily (Italy).

Magnetostratigraphic age calibration and subsequent spectral analysis of the variatrions in CaCO3 content yield a remarkably consistent discrepancy between the resulting periodicities and the corresponding quasi‐periods of the Earth's orbital cycles. This discrepancy can only be explained by assuming that ages assigned to polarity reversal boundaries in the geomagnetic polarity time‐scale lack sufficient precision.

A new polarity time‐scale is presented for the major part of the Gilbert and Gauss Chron using the radiometrically dated Gilbert‐Gauss Chron boundary at 3.40 Ma as an age reference point and extrapolating an average quasi‐period of 21.7 kyr of the precession cycle as the periodicity of small‐scale colour annex CaCO3 cycles.
Milankovitch control of foraminiferal assemblages from the Cenomanian of southern England
Authors: Leary P.N. , Cottle R.A. , Ditchfield P.
Published: July 2007

A succession of foraminiferal assemblages recorded across three Cenomanian marl chalk‐marl rhythms is interpreted as a function of occasional high pelagic carbonate production induced by warmer surface waters. The changes in the benthonic assemblages are related to the introduction of increased amounts of carbonate sediment, Fluctuations in surface water temperature and associated productivity changes may be a consequence of orbital (precessional) forcing of the climate. Chalk formation is likely to have been much more rapid than marl formation.
A Milankovitch scale for Cenomanian time
Authors: Gale Andrew S.
Published: July 2007

A detailed cyclostratigraphy is present in the rhythmically bedded Cenomanian hemipelagic chalks of the northern Anglo‐Paris Basin, which can be correlated over 100,000 km2. Individual decimetre‐scale couplets probably represent the precession cycle (modes at 18 or 23 kyr), and can be readily grouped in sets averaging five, indicative of the short cycle of eccentricity (100 kyr). A composite cyclostratigraphy for the basin is presented here, and is used as the basis for a Cenomanian time‐scale (20 and 100 kyr units). The total duration of the Cenomanian thus obtained (4.4 Myr) compares well with recent radiometric dates of 4.0–4.5 Myr. The time‐scale is used to estimate the length of ammonite, inoceramid, and planktonic foraminiferal zones, the rates of formation of authigenic minerals (glauconite), sedimentation rates and the duration of transgressions and anoxic events.
Orbitally mediated cycles from the Turonian of southern England: their potential for high‐resolution stratigraphic correlation
Authors: Cottle R.A.
Published: July 2007

Detailed sampling of two sections of Turonian‐aged Chalk from southeast England for foraminifera has revealed that cyclical abundance changes in many species and genera were mediated by orbitally induced climatic cycles. These cycles can be used for high‐resolution stratigraphic correlation of the two sections and as a possible means of re‐estimating the duration of the Turonian period.
Cyclic geomagnetic changes in Mid‐Cretaceous rhythmites, Italy
Authors: Napoleone Giovanni , Ripepe Maurizio
Published: July 2007

Magnetic secular variation is recorded as a quasi‐rhythmical process of uncertain origin. Rhythmic changes recorded in the Scisti a Fucoidi in the central Apennines of Italy, pelagic sediments of Mid‐Cretaceous (Late Albian) age, show strong correspondence to patterns of orbital variation. In the same strata cyclic magnetic variations are found with peaks in the same range (105, 40, 26,19 kyr). These results appear to support earlier suggestions that secular variations may be related to these astronomical patterns.
Planktonic foraminiferal distribution record productivity cycles: evidence from the Aptian‐Albian Piobbico core (central Italy)
Authors: Silva Lsabella Premoli , Ripepe Maurizio , Tornaghi M. Emilia
Published: July 2007

The Aptian‐Albian ‘Scisti a Fucoidi’ varicoloured pelagic sediments in central Italy, show a ‘couplet’ alternation of carbonate‐rich/carbonate‐poor layers, which are interpreted as the sedimentary expression of precession (frequency 19–23 kyr). Carbonate content, chromatic variation, and planktonic foraminiferal abundance were analysed at a 1‐cm spacing for a 10‐m interval of the Piobbico core, specifically drilled through this formation. Spectral analysis of these parameters shows a prominent signal equated to the c. 100 kyr cycle of orbital eccentricity at a sedimentation rate of 5 mm kyr−1. The coherency of the spectral response of each parameter suggests that a single mechanism controlled the whole sedimentary record. Detailed study of planktonic foraminiferal distribution of the same section at 1‐mm scale resolves the Milankovitch frequencies of 41 kyr and 18 to 23 kyr, equated with the obliquity and precessional cycles. But foraminiferal abundance is not in phase with carbonate content, which was largely controlled by calcareous nannofossils, but peaked at intermediate carbonate values. The proposed model for explaining the discrepancy at the precessional level is that foraminifera thrived at intermediate values of the precession index, when the environment was only moderately fertile but stable, while during highs of the precession index, mixing of the water column increased fertility and caused calcareous nannofossil blooms and restriction of planktonic foraminifera to few and tolerant species. The resulting bimodality of foraminiferal abundance per precessional cycle appears to be recorded in the spectrum by peaks at the 11 and 14 kyr levels. Cross correlation of foraminiferal abundances with the calcium carbonate curve over 1–2 Myr intervals produces discrepant results (apparent phase lags) which we attribute to differences in the response to the fundamental eccentricity cycles.
Rhythmic pelagic successions and terrestrial orbital variations. The example of the Lower Cretaceous from Angles (SE France)
Authors: Rio Michel , Cotillon Pierre , Ferry Serge
Published: July 2007

An harmonic analysis of limestone bed and marl interbed thicknesses of pelagic Berriasian‐Barremian interval from the Angles area (SE France) shows that marly parts of the succession contain frequencies significantly different from calcareous ones. Some of the resulting periods are in the Milankovitch frequency band but many others are different from those predicted by the orbital theory.
Stratigraphic correlation of presumed Milankovitch cycles in the Blue Lias (Hettangian to earliest Sinemurian), England
Authors: Smith David G.
Published: July 2007

Simple digital filtering methods allow the correlation of patterns of metre‐scale cycles between outcrop sections and well logs through the Hettangian to earliest Sinemurian part of the Lower Lias in southern England. The matching of cyclic patterns is sufficiently confident to allow the identification of a significant break in the Blue Lias section at Lyme Regis (Dorset). The standard ammonite zones of the Hettangian Stage are shown to be of quantifiably unequal duration.
Astronomical frequencies for pre‐Quaternary palaeoclimate studies
Authors: Berger A. , Loutre M.F. , Dehant V.
Published: July 2007

The sensitivity of the Earth's orbital frequencies, involved in the astronomical theory of palaeoclimates, to the Earth‐Moon distance and consequently to the length of the day and to the dynamical ellipticity of the Earth has been investigated for the last billion years. The shortening of the Earth‐Moon distance and of the length of the day back in time induces a shortening of the fundamental astronomical periods for the obliquity and the precession, a shortening which is larger for the longer periods. These periods of precession and obliquity influenced by the changing Earth‐Moon distance, length of the day and dynamical ellipticity of the Earth, have been recomputed for the last 440 million years.