bluuebunny/crossref_metadata_2025 huggingface dataset:
Clone differentiation and varietal identification by means of SSR, AFLP, SAMPL and M‐AFLP in order to assess the clonal selection of grapevine: the case study of Manto Negro, Callet and Moll, autochthonous cultivars of Majorca
Authors: Cretazzo E. , Meneghetti S. , De Andrés M.T. , Gaforio L. , Frare E. , Cifre J.
Published: June 2010

Clonal selection is the most worldwide spreading method to improve the performance of wine grapevine (Vitis vinifera) cultivars. In the special case of autochthonous varieties with only local interest, such as Manto Negro, Callet and Moll in Majorca (Spain), good knowledge of their genotypic resources is helpful to assess the development of viticultural and enological potentialities.

In this study, 94 vines (including Manto Negro, Callet, Moll and wrongly identified samples) were analysed by means of genetic markers.

Several varietal identification mistakes related to the clonal selection in Majorca were detected by the amplification of 33 simple sequence repeats (SSRs) or microsatellite loci, mainly because of the close genetic relationships between Manto Negro, Callet, Moll and other varieties.

A very low degree of intravarietal genetic diversity, possibly related to high incidence of virus infections, was shown in all three varieties. However, analysis by amplified fragment length polymorphism (AFLP), selective amplification of microsatellite loci (SAMPL) and microsatellite‐amplified fragment length polymorphism (M‐AFLP) was suitable for clone genetic discrimination. More than 900 scorable bands were obtained by nine primer combinations. The most efficient system to detect intravarietal genetic differences was M‐AFLP, which generated the highest number of polymorphic bands. The use of these markers allowed clustering vines in homogeneous groups, providing essential information about sanitation strategies in order to obtain certified propagation material.
Hope for Tropical Biodiversity through True Bioliteracy
Authors: Janzen Daniel H.
Published: June 2010

For tropical wild biodiversity to survive, it must occupy a large terrain, be permanently endowed, and be integrated with its local, national, and international society. Among other things, integration will be enormously facilitated by giving bioilliterate humanity—all seven billion of us—the ability to read wild biodiversity anywhere any time for the personal cost of a pocket comb. That is true universal bioliteracy. DNA barcoding is the technology for this, and a personal or an institutional decision to sustain its cheap cost will cut the Gordian knot.
A proposal on the galaxy intrinsic alignment self-calibration in weak lensing surveys
Authors: Zhang Pengjie
Published: June 2010

The galaxy intrinsic alignment causes the galaxy ellipticity–ellipticity power spectrum between two photometric redshifts to decrease faster with respect to the redshift separation ΔzP, for fixed mean redshift. This offers a valuable diagnosis on the intrinsic alignment. We show that the distinctive dependences of the GG, II and GI correlations on ΔzP over the range |ΔzP| ≲ 0.2 can be understood robustly without strong assumptions on the intrinsic alignment. This allows us to measure the intrinsic alignment within each conventional photo-z bin of typical size ≳0.2, through lensing tomography of photo-z bin size ∼0.01. Both the statistical and systematical errors in the lensing cosmology can be reduced by this self-calibration technique.
Emergency department ultrasound by nurse practitioners
Authors: Henderson Sean O. , Ahern Terence , Williams David , Mailhot Thomas , Mandavia Diku
Published: June 2010

Purpose: Bedside ultrasound (u/s) examinations by emergency physicians (EPs) have been integrated into clinical emergency medicine (EM) training programs and the efficacy and success of an introductory u/s training course, based on established guidelines, has been previously described. We used this same course to teach EM nurse practitioners (NPs) bedside u/s and then assessed the adequacy of NP ultrasonography 1 year following the course.

Data sources: Five NPs were included in a standardized 16‐h EM u/s training program. Subsequently, the NPs were asked to print consecutive u/s images representative of their clinical assessments. A single qualified EP reviewer assessed images for adequacy.

Conclusions: Five NPs reported 229 u/s examinations, two of which were excluded as nondiagnostic over the 2‐month study period. There were 32 inadequate images and 27 “positive” findings. All the positives were correct. Totals per provider were 104, 58, 49, 13, and 3 u/s assessments with 83%, 95%, 84%, 77%, and 100% adequacy of images, respectively. Of the 32 inadequate images, 18 of these were incomplete focused assessment with sonography for trauma (FAST) examinations with a reading of negative for free fluid.

Implications for practice: NPs are able to perform focused u/s with a high degree of accuracy, and a 16‐h guideline‐based course serves as a good introductory foundation.
Managing inflammatory arthritides: Role of the nurse practitioner and physician assistant
Authors: Lesko Mary , Young Melodie , Higham Robert
Published: June 2010

Purpose: To review the current management of the inflammatory arthritides, including rheumatoid arthritis, ankylosing spondylitis, and psoriatic arthritis. This review examines the role of the nurse practitioner (NP) and physician assistant (PA) in the management of these chronic diseases.

Data sources: A review of the scientific literature and current guidelines regarding the management of inflammatory arthritides.

Conclusions: NPs and PAs play important roles in the interdisciplinary team involved in the treatment of patients with chronic inflammatory arthritic conditions. The management of inflammatory arthritides has evolved with the development of new treatment strategies and is focused on early intervention and minimizing progressive joint damage. NPs and PAs are ideally positioned to educate patients regarding treatment options and other important aspects of the disease process and to monitor disease activity using a number of validated instruments.

Implications for practice: Through active disease management, NPs and PAs can influence their patients to make better, more informed choices regarding treatment, which may optimize patient outcomes.
Mechanisms of exocytosis
Authors: Sugita S.
Published: June 2010

Catecholamines and peptides secreted from dense‐core vesicles (DCVs) of adrenal chromaffin cells regulate a wide variety of physiological processes. For instance, the release of noradrenaline and adrenaline plays a key role in regulating heart rate and blood pressure. Thus understanding the mechanisms of secretory processes of DCVs is crucial for understanding the basis of diseases such as hypertension. DCVs undergo several stages of secretory processing before they are exocytosed. These include docking, priming and triggering of membrane fusion/exocytosis. Molecular studies of DCV exocytosis have identified many proteins critically involved in DCV secretion. These proteins include SNARE proteins, Munc18‐1, phsophatidylinositol transfer protein, type I phosphatidylinositol‐4‐phosphate‐5‐kinases, NSF, Munc13, CAPS1, synaptotagmins, RalA/RalB GTPases and exocyst proteins. In this article, I will discuss the functions of these proteins within the context of the stages (i.e. docking, priming and triggering of membrane fusion/exocytosis) in DCV secretion.
Accidental Traumatic Head Injury in Infants and Young Children
Authors: Case Mary E.
Published: June 2010

This article will discuss accidental head injuries in infants and young children. The first category of injury is the crushing head injury. Static forces applied slowly to the head result in multiple fractures of the skull and contusions and lacerations of the brain resulting from the bone fragments striking the brain.

This article will discuss the subject of short falls in young children and the resulting head injuries. Because falls are frequent events in early life, many cases have been collected and many papers written on the subject. Study of these cases is informative about the injuries likely to occur in these falls. Most often, only a minor contact injury such as scalp bruise or laceration results. In a 2 to 3% of falls, a simple linear skull fracture occurs and the majority of these are uneventful in terms of neurological deficit or intracranial bleeding. In about 1% of the fractures, an epidural or subdural hemorrhage occurs. Each of these forms of contact hemorrhages will be discussed and illustrated. While these are relatively rare injuries, it is essential that they can be identified as consistent with an accidental mechanism so that an erroneous diagnosis of inflicted injury is not made.
Impacts of Shewanella oneidensis c‐type cytochromes on aerobic and anaerobic respiration
Authors: Gao Haichun , Barua Soumitra , Liang Yili , Wu Lin , Dong Yangyang , Reed Samantha , Chen Jingrong , Culley Dave , Kennedy David , Yang Yunfeng , He Zhili , Nealson Kenneth H. , Fredrickson James K. , Tiedje James M. , Romine Margaret , Zhou Jizhong
Published: June 2010

Shewanella are renowned for their ability to utilize a wide range of electron acceptors (EA) for respiration, which has been partially accredited to the presence of a large number of the c‐type cytochromes. To investigate the involvement of c‐type cytochrome proteins in aerobic and anaerobic respiration of Shewanella oneidensis Mr ‐1, 36 in‐frame deletion mutants, among possible 41 predicted, c‐type cytochrome genes were obtained. The potential involvement of each individual c‐type cytochrome in the reduction of a variety of EAs was assessed individually as well as in competition experiments. While results on the well‐studied c‐type cytochromes CymA(SO4591) and MtrC(SO1778) were consistent with previous findings, collective observations were very interesting: the responses of S. oneidensis Mr ‐1 to low and highly toxic metals appeared to be significantly different; CcoO, CcoP and PetC, proteins involved in aerobic respiration in various organisms, played critical roles in both aerobic and anaerobic respiration with highly toxic metals as EA. In addition, these studies also suggested that an uncharacterized c‐type cytochrome (SO4047) may be important to both aerobiosis and anaerobiosis.
Epithelial marker expression in Salzmann nodular degeneration shows characteristics of limbal transient amplifying cells and alludes to an involvement of the epithelium in its pathogenesis
Authors: Eberwein Philipp , Hiss Sonja , Auw‐Haedrich Claudia , Sundmacher Rainer , Hauer Katharina , Boehringer Daniel , Meier Peter , Reinhard Thomas
Published: June 2010

Purpose:  To look at the epithelial nature of Salzmann nodular degeneration (SND) and its possible relation with the aetiology of the subepithelial collagen deposition.

Methods:  Histological slides of 28 patients with SND were analysed for limbal and central corneal epithelial markers. Expression pattern of these markers in the basal layer of the epithelium was analysed and compared to the expression pattern in central corneal and limbal epithelium. Statistical analysis was performed by means of analysis of variance.

Results:  Expression of the epithelial stem cell marker ABCG2 and p63 was low in SND. Expression of CK12, a marker for terminally differentiated epithelium, was low, as well. But, CK19 and Enolase‐alpha expressions were significantly increased and resembled the expression pattern of transient amplifying cells (TAC) of the limbus.

Conclusion:  The epithelium in SND shows similar characteristics as TAC of the limbus and seems to be metabolically more active than the differentiated central corneal epithelium. This could be related to the deposition of subepithelial collagen fibrils seen in SND and points out a possible involvement of the corneal epithelium in the aetiology of Salzmann nodular degeneration.
Primary monophasic synovial sarcoma of the pleura: Neoadjuvant chemotherapy followed by complete resection
Authors: Silva Ramiro G.M. , Gross Jefferson L. , Silva Rodrigo A. , Haddad Fabio J. , Younes Riad N. , Cruz Vasco M. , Avertano‐Rocha Antonio B.M.
Published: June 2010

We describe a rare case of primary pleural synovial sarcoma in a 27‐year‐old man with a 4‐month history of dry cough and left‐sided chest pain. A CT scan showed a large cystic mass in the left pleural cavity. The patient underwent two video‐assisted thoracoscopic biopsies and the diagnosis of synovial sarcoma of the pleura was established. After neoadjuvant chemotherapy, which resulted in a partial response, the tumor was completely resected with extrapleural pneumonectomy. Pathological findings showed less than 5% of viable cancer and free surgical margins. The patient is clinically well 24 months after surgery, with no evidence of recurrent disease.
Longitudinal Investigation of Methicillin‐Resistant Staphylococcus aureus in Piglets
Authors: Weese J. S. , Zwambag A. , Rosendal T. , Reid‐Smith R. , Friendship R.
Published: June 2010

Methicillin‐resistant Staphylococcus aureus (MRSA) has emerged as an important public health concern and pigs have been implicated in human infections. Cross‐sectional studies have demonstrated that MRSA can be commonly found in pigs internationally, but little is known about age‐related changes in MRSA colonization. This study evaluated MRSA colonization in piglets in a longitudinal manner. Serial nasal swabs were collected from piglets born to 10 healthy sows. The prevalence of MRSA colonization on days 1, 3, 7, 14 and 21 was 1% (1/100), 6.2% (3/97), 8.5% (8/94), 4.4% (4/91) and 20% (18/91) respectively, with an overall pre‐weaning prevalence of 34.5%. The prevalence on days 28, 42, 56 and 70 was 34% (31/91), 65% (57/88), 50% (44/88) and 42% (36/87) respectively, with an overall post‐weaning prevalence of 85%. Eighty‐four percent of piglets from negative sows and 100% of piglets from positive sows that survived at least until the time of weaning were colonized with MRSA at one or more times during the study. There was a significant association between sow and piglet colonization. The age of the piglet was significantly associated with the probability of colonization. No piglets or sows received antimicrobials during the study period. These results indicate that age must be considered when designing surveillance programmes and interpreting results of different studies on MRSA.
Laminar inflammatory gene expression in the carbohydrate overload model of equine laminitis
Authors: LEISE B. S. , FALEIROS R. R. , WATTS M. , JOHNSON P. J. , BLACK S. J. , BELKNAP J. K.
Published: June 2010

Reasons for performing study:There is a need to assess the laminar inflammatory response in a laminitis model that more closely resembles clinical cases of sepsis‐related laminitis than the black walnut extract (BWE) model.

Objectives:To determine if a similar pattern of laminar inflammation, characterised by proinflammatory cytokine expression, occurs in the CHO model of laminitis as has been previously reported for the BWE model.

Methods:Sixteen horses administered 17.6 g of starch (85% corn starch/15% wood flour)/kg bwt via nasogastric (NG) tube were anaesthetised either after developing a temperature >38.9°C (DEV group, n = 8) or at onset of Obelgrade 1lameness (OG1 group, n = 8). Control horses (CON group, n = 8) were anaesthetised 24 h after NG administration of 6 l of deionised water. Laminar tissue was collected from horses while under anaesthesia, followed by humane euthanasia. Real time‐quantitative PCR was used to assess laminar mRNA concentrations of genes involved in inflammatory signalling.

Results:Increased mRNA concentrations (P<0.05) for IL‐1β, IL‐6, IL‐12p35, COX‐2, E‐selectin and ICAM‐1 were present in laminae from horses with OG1 lameness but not at the DEV time, when compared to the CON horses. No differences between the groups were found for IL‐2, IL‐4, IL‐10, TNF‐α, IFN‐γ or COX‐1 at either the DEV or OG1 time points.

Conclusions:There was a notable difference in the temporal pattern of inflammatory events between the BWE and CHO models, with the majority of laminar inflammatory events appearing to occur at or near the onset of lameness in the CHO model, whereas many of these events peak earlier in the developmental stages in the BWE model. This suggests that, in addition to circulating inflammatory molecules, there may be a local phenomenon in the CHO model resulting in the simultaneous onset of multiple laminar events including endothelial activation, leucocyte emigration and proinflammatory cytokine expression.

Potential relevance:The similar (although somewhat delayed) inflammatory response in the CHO model of laminitis indicates that inflammatory signalling is a consistent entity in the pathophysiology of laminitis.
Serum biomarker levels for musculoskeletal disease in two‐ and three‐year‐old racing Thoroughbred horses: A prospective study of 130 horses
Authors: FRISBIE D. D. , Mc ILWRAITH C. W. , ARTHUR R. M. , BLEA J. , BAKER V. A. , BILLINGHURST R. C.
Published: June 2010

Reason for performing study:Biomarkers have shown somein vivopromise for the detection of musculoskeletal injuries, but further study to assess biomarker levels in clinical orthopaedic disease is required.

Objective:To assess 7 serum biomarkers for the detection of musculoskeletal injuries.

Methods:Two‐ and 3‐year‐old racehorses were entered into the study (n = 238). Exit criteria were lack of training for >30 days, or completion of 10 study months. Data from horses with solitary musculoskeletal injuries and completion of >2 months were analysed. Musculoskeletal injury was considered intra‐articular fragmentation (IAF), tendon or ligamentous injury (TL), stress fractures (SF) and dorsal metacarpal disease (DMD). Monthly lameness examination and serum collection were performed. Serum was analysed for glycosaminoglycan (GAG),type IandIIcollagen degradation (C1, 2C),type IIcollagen synthesis (CPII),type IIcollagen degradation (Col CEQ), aggrecan synthesis (CS846), osteocalcin (OC) as a marker of bone formation and (C‐terminal telopeptide oftype Icollagen) CTX as a marker of bone degradation.

Results:Of the 238 horses 59 injured and 71 uninjured control horses met the analysis criteria. Based on injury no significant differences in the proportions were observed for age, gender or lesion type, although a higher proportion of injuries occurred at the beginning of the study. Of injured horses, 16 (27%) sustained an IAF, 17 (29%) a TL injury, 7 (12%) SF and 19 (32%) were diagnosed with DMD. There were significant changes seen in biomarkers based on the injury incurred when longitudinal samples were assessed. Furthermore, based on the serum biomarkers collected prior to injury, horses could be correctly classified as injured or uninjured 73.8% of the time.

Conclusions:A unique biomarker pattern occurred before each injury and this was beneficial in classifying horses as injured or uninjured.

Potential relevance:Biomarkers have the potential to be used as a screening aid prior to musculoskeletal injury.
Exercising upper respiratory videoendoscopic evaluation of 100 nonracing performance horses with abnormal respiratory noise and/or poor performance
Authors: DAVIDSON E. J. , MARTIN B. B. , BOSTON R. C. , PARENTE E. J.
Published: June 2010

Reasons for performing study:Although well documented in racehorses, there is paucity in the literature regarding the prevalence of dynamic upper airway abnormalities in nonracing performance horses.

Objective:To describe upper airway function of nonracing performance horses with abnormal respiratory noise and/or poor performance via exercising upper airway videoendoscopy.

Methods:Medical records of nonracing performance horses admitted for exercising evaluation with a chief complaint of abnormal respiratory noise and/or poor performance were reviewed. All horses had video recordings of resting and exercising upper airway endoscopy. Relationships between horse demographics, resting endoscopic findings, treadmill intensity and implementation of head and neck flexion during exercise with exercising endoscopic findings were examined.

Results:Dynamic upper airway obstructions were observed in 72% of examinations. Head and neck flexion was necessary to obtain a diagnosis in 21 horses. Pharyngeal wall collapse was the most prevalent upper airway abnormality, observed in 31% of the examinations. Complex abnormalities were noted in 27% of the examinations. Resting laryngeal dysfunction was significantly associated with dynamic arytenoid collapse and the odds of detecting intermittent dorsal displacement of the soft palate (DDSP) during exercise in horses with resting DDSP was only 7.7%. Exercising endoscopic observations were different from the resting observations in 54% of examinations.

Conclusions:Dynamic upper airway obstructions were common in nonracing performance horses with respiratory noise and/or poor performance. Resting endoscopy was only helpful in determining exercising abnormalities with recurrent laryngeal neuropathy.

Potential relevance:This study emphasises the importance of exercising endoscopic evaluation in nonracing performance horses with abnormal respiratory noise and/or poor performance for accurate assessment of dynamic upper airway function.
Numerical Modeling of Perforated Tile Flow Distribution in a Raised-Floor Data Center
Authors: Samadiani Emad , Rambo Jeffrey , Joshi Yogendra
Published: June 2010

This paper is centered on quantifying the effect of computer room and computer room air conditioning (CRAC) unit modeling on the perforated tile flow distribution in a representative raised-floor data center. Also, this study quantifies the effect of plenum pipes and perforated tile porosity on the operating points of the CRAC blowers, total CRAC air flow rate, and its distribution. It is concluded that modeling the computer room, the CRAC units, and/or the plenum pipes could make an average change of up to 17% in the tile flow rates with a maximum of up to 135% for the facility with 56% open tiles while the average and maximum changes for the facility with 25% open tiles are 6% and 60%, respectively.
Evaluation of the Dominant Factor for Electromigration in Sputtered High Purity Al Films
Authors: Zhao X. , Saka M. , Yamashita M. , Togoh F.
Published: June 2010

This paper is focused on evaluating the dominant factor for electromigration (EM) in sputtered high purity Al films. A closed-form equation of atomic flux divergence by treating grain boundary diffusion and hillock formation in a polycrystalline structure without passivation layer was derived to construct the theoretical model. According to the developed equation, it is available to see the effect of various parameters on the EM resistance. Moreover, based on the proposed model, we compared the EM resistance of different sputtered high purity Al films. These films differ in purity and features, which are realized as affecting factors for the EM resistance. Finally, according to the analysis by the synthesis of the obtained EM resistance, the evaluation of the dominant factor for EM in sputtered high purity Al films was approached. Although the effects of the average grain size and the effective valence cannot be ignored, the difference in diffusion coefficient was believed to have a dominant influence in determining the EM resistance. Thus, increasing the activation energy for grain boundary diffusion can significantly reduce the damage during EM in such sputtered polycrystalline Al films.
Hygro-Thermo-Mechanical Reliability Assessment of a Thermal Interface Material for a Ball Grid Array Package Assembly
Authors: Liu Xi , Zheng Jiantao , Sitaraman Suresh K.
Published: June 2010

The thermal efficacy of thermal interface material (TIM) is highly dependent on its ability to adhere to the surfaces of interest. Any delamination of the TIM from the die or the lid will increase the local thermal resistance and, thus, will reduce the overall effectiveness of the TIM. Although significant amount of work has been done on understanding the thermal and moisture effects of various polymer materials used in microelectronic package assemblies, very limited work has been done to study the effect of temperature and moisture on TIM delamination. In this paper, a sequential hygro-thermal-mechanical finite-element model has been developed to mimic the loadsteps associated with package assembly as well as moisture soaking under 85°C/85RH over 500 h. The predictions from the models have been validated with a wide range of experimental data including laser Moiré data for thermomechanical loading and digital image correlation data for hygro-thermo-mechanical loading. Weight gain and coordinate-measurement machine have been used to characterize moisture diffusivity and moisture expansion coefficient of various polymer materials in the package assembly. The developed models show the evolution of normal strain in TIM during various loadsteps and provide important insight into the potential for TIM delamination under package assembly process and moisture soaking. Thus, the models can be used for developing various designs and process steps for reducing the chances for TIM delamination.
Board-Level Solder Joint Reliability Study of Land Grid Array Packages for RF Application Using a Laser Ultrasound Inspection System
Authors: Yang Jin , Zhang Lizheng , Ume I. Charles , Ghiu Camil , White George
Published: June 2010

Microelectronics packaging technology has evolved from through-hole, and bulk configuration to surface-mount, and small-profile ones. Today’s electronics industry is also transiting from SnPb to Pb-free to meet environmental requirements. Land grid array (LGA) package has been becoming popular in portable electronics in terms of low profile on the printed wiring boards and direct Pb-free assembly process compatibility. With the package profile shrinking and operating power increasing, solder joint quality and reliability has become a major concern in microelectronics manufacturing. The solder joint failure at the package level or board level will cause electronic devices not to function during service. In this paper, board-level solder joint reliability of the LGA packages under thermal loading is studied through thermal cycling tests. A novel laser ultrasound-interferometric system developed by the authors is applied to inspect solder joint quality during the thermal cycling tests. While the laser ultrasound inspection technique has been successfully applied to flip chips and chip scale packages, this study is the first application of this technique to overmolded packages. In this study, it is found out that the LGA packages can withstand 1000 temperature cycles without showing crack initiation or other failure mechanisms in the solder joints. The laser ultrasound inspection results match the visual observation and X-ray inspection results. This study demonstrates the feasibility of this system to solder joint quality inspection of overmolded packages. In particular, the devices constituting the objective of this study are radio frequency modules, which are encapsulated through overmolding and are mounted on a typical four-layer FR4 board through LGA terminations.
Tissue-Engineered Lungs for in Vivo Implantation
Authors: Petersen Thomas H. , Calle Elizabeth A. , Zhao Liping , Lee Eun Jung , Gui Liqiong , Raredon MichaSam B. , Gavrilov Kseniya , Yi Tai , Zhuang Zhen W. , Breuer Christopher , Herzog Erica , Niklason Laura E.
Published: June 2010

Waiting to Exhale

Lung tissue does not regenerate, so, when it is damaged by disease and/or surgically removed, lung transplantation is often the only treatment option. Because donor tissue is in short supply, there has been a long-standing interest in engineering functional and transplantable lung tissue in the laboratory.

Petersen
et al.

(p.
538
, published online 24 June; see the Perspective by

Wagner and Griffith

) now report an important step in this direction. After gently removing the cellular constituents of rat lungs with detergent, the residual scaffold of extracellular matrix—which retained the compliance and mechanical properties of the original lung—was re-seeded with a mixture of lung epithelial and endothelial cells and cultured in a bioreactor. Within a few days, the engineered lung tissue contained alveoli, microvessels, and small airways that were repopulated with the appropriate cell types. When transplanted into a rat for short time periods, the engineered lung showed evidence of gas exchange.
Asymmetric Density Dependence Shapes Species Abundances in a Tropical Tree Community
Authors: Comita Liza S. , Muller-Landau Helene C. , Aguilar Salomón , Hubbell Stephen P.
Published: June 2010

Too Close to Home?

Why are some species common while others are exceedingly rare? Attempts to answer this question have met limited success, particularly in hyperdiverse communities, such as tropical forests.

Comita
et al.

(p.
330
, published online 24 June; see the cover) reveal a previously overlooked explanation. A large data set on seedling dynamics of 180 tree species on Barro Colorado Island, Panama, combined with Bayesian statistical techniques, revealed that species abundance is shaped by the degree to which species negatively impact their own regeneration. Rare species regenerated far less well than common species in the proximity of conspecific neighbors, suggesting a mechanism determining the relative abundances of tree species in highly diverse tropical forest communities.
Mineralization at the Golden Grove Cu – Zn deposit, Western Australia. II: Deformation textures of the opaque minerals
Authors: Frater Kenneth Maxwell
Published: June 2010

Studies of the sulphide–magnetite fabric at Golden Grove. Western Australia, metamorphosed under conditions of lower to middle greenschist facies, indicate that pyrite and magnetite deformed in a brittle manner, whereas pyrrhotite, sphalerite, chalcopyrite, and galena deformed as ductile sulphides. In the accompanying silicate assemblage, pressure-solution deformation has been a significant deformation mechanism. An optical-microscope study of etched sphalerite reveals a wide range of microstructures indicative of ductile deformation, including lattice dislocations, subgrains and subboundaries, annealing twins, variable grain-boundary geometry, and recrystallization. The microstructures are distributed randomly through the sphalerite fabric and are similar to that formed during steady-state creep of deformed metals and that reported in dynamic recovery and recrystallization of deformed quartz. It is concluded that the ductile sulphides are modified by synkinematic recovery and recrystallization and that postkinematic recovery, annealing, and recrystallization, which are commonly reported for sulphide deposits, are not present.
Paleomagnetism of Archean rocks from northwestern Ontario: V. Poohbah Lake alkaline complex, Quetico Subprovince
Authors: Dunlop David J.
Published: June 2010

The Poohbah Lake alkaline complex is a late synkinematic Kenoran pluton in the Quetico gneiss belt of the western Superior Province. Three units of the complex, porphyritic syenite (PS), malignite (M: a nepheline–clinopyroxene–K-feldspar rock), and hornblende syenite (HS), as well as baked Archean schists near the intrusive contact, have a predominantly reverse-polarity R magnetization with mean direction D = 198° I = −22.5° (k = 62, α95 = 5°, N = 13 sites) and a paleopole at 60°E, 50.5°N. Pyrrhotite and coarse primary magnetite are carriers of the R remanence. PS, M, and biotite pyroxenite (BP) exhibit also a predominantly normal N magnetization carried by fine-grained, probably secondary magnetite. N is systematically steeper than R: its mean direction is D = 359.5° I = +55.5° (k = 28, α95 = 8°, N = 13 sites) with a paleopole at 90°E, 77.5°N. R and N do not record an asymmetric field reversal, since reverse-polarity N vectors and normal-polarity R vectors are occasionally found. R resembles in polarity and direction the natural remanent magnetization (NRM) of the 2630 Ma Matachewan diabase. It is probably the primary NRM of the Poohbah Lake pluton, with an age of about 2650 Ma in approximate agreement with the K/Ar isochron age of 2700 ± 25 Ma. N resembles in polarity and direction NRM's from the 2580 Ma Shelley Lake granite and the late Archean Burchell Lake granite. It is probably a secondary NRM about 2550 Ma in age, as suggested by updated K/Ar mica ages. The characteristic NRM of HS samples and secondary magnetizations in other rock types have poles on the Grenville Track of the polar wander path but there is no evidence for Grenvillian-age events in the area.
The Iceland Research Drilling Project crustal section: variation of magnetic properties with depth in Icelandic-type oceanic crust
Authors: Hall James M.
Published: June 2010

An attempt has been made to identify the processes that give rise to a number of depth trends in the magnetization of a 3.1 km vertical section of Icelandic-type oceanic crust and to assess the possibility that similar processes act, and depth trends occur, in typical oceanic crust. The depth trends in the Icelandic section consist of a general increase in saturation and induced magnetization to 2 km crustal depth, below which flow magnetization decreases while dike magnetization remains constant, and of large changes in flow magnetization that occur on a scale of a few hundred metres below 3 km crustal depth.Increase in saturation and induced magnetization with depth in the upper 2 km is thought to be the result of two processes: a decrease in low-temperature oxidation from the original lava surface to 700–800 m crustal depth, thence an increase in hydrothermal alteration with depth. This interpretation is based on oxide petrography and Curie temperatures, which show a weakly defined minimum in the 700–800 m interval, then an increase to ubiquitous "magnetite" values at just below 2 km crustal depth. Although the relationship between magnetic properties and oxide alteration is reasonably well known for the low-temperature oxidation process from laboratory studies and ophiolite and typical ocean-crust analogs, the change in magnetic properties during hydrothermal alteration is not generally known, nor are ophiolite or typical ocean-crust analogs presently available.Decrease in flow saturation and induced magnetization below 2 km is likely to be the result of alteration of magnetite (sensu lato) to nonmagnetic phases, either on a fine scale to hematite (s.l.) between 2 km and 3 km, or by leaching of iron, leaving anatase pseudomorphs after magnetite (s.l.) below 3 km. The relatively low porosity of the dikes is likely to have protected dike magnetite below 2 km from such oxidation and leaching processes.The study confirms that secondary magnetite in several forms is an important magnetic constituent of the flows in the lower part of the section, particularly where decomposition of primary magnetite is widespread. Secondary magnetite occurs as vermiform or bladelike masses, as rims associated with former silicates, or as fresh continuous magnetite occurring either as subhedral grains or as "reconstructed" primary grains in which relics of sphene-replaced ilmenite lamellae grids are seen.In conclusion, the possibility that the near-surface magnetization of typical ocean crust is commonly the minimum value for a layer extending downwards to the onset of an epidote-bearing facies deserves serious consideration, as does the possibility that strong, stable magnetization of secondary origin occurs in flows where dike density becomes significant.
Uniform-sense normal simple shear of the continental lithosphere
Authors: Wernicke Brian
Published: June 2010

Geophysical studies suggest that the thin crust characteristic of the Basin and Range Province extends eastward beneath the west margin of the Colorado Plateau and Rocky Mountain regions. In Arizona and Utah, zones perhaps over 100 km wide may be defined, bounded on the west by the east limit of upper crustal normal faults that account for more that 10% extension and on the east by the east limit of thinning beneath the Colorado Plateau. A discrepancy exists within these zones between the negligible extension measurable in the upper crust and the substantial extension apparent from crustal thinning, assuming the "discrepant zone" crust was as thick as or thicker than the Colorado Plateau – Rocky Mountain crust prior to extensional tectonism.If various theories appealing to crustal erosion are dismissed, mass balance problems evident in the discrepant zones are most easily resolved by down-to-the-east normal simple shear of the crust, moving lower and middle crustal rocks that initially were within the zones up-and-to-the-west to where they now are locally exposed in the Basin and Range Province. West of the discrepant zones in both Arizona and Utah, east-directed extensional allochthons with large displacement are exposed. These geophysical and geological observations complement one another if it is accepted that the entire crust in both Arizona and Utah failed during extension on gently east-dipping, east-directed, low-angle normal faults and shear zones over a region several hundred kilometres wide.Large-scale, uniform-sense normal simple shear of the crust suggests the entire lithosphere may do the same. Such a hypothesis predicts major lithospheric thinning without crustal thinning will occur in plateau areas in the direction of crustal shear. In the case of the Arizona, Utah, and Red Sea extensional systems, and possibly the Death Valley extensional terrain, a broad topographic arch, typically 1500–2000 m higher than the extended terrain, is present, suggesting lithospheric thinning in areas predicted by the hypothesis.
LITHOPROBE seismic reflection imaging of Rocky Mountain structures east of Canal Flats, British Columbia
Authors: Eaton David W. S. , Cook Frederick A.
Published: June 2010

LITHROPROBE seismic reflection data, coupled with information from industry seismic data and surface geology, image the thin-skinned structures of the western Rocky Mountains from the Main Ranges to the Rocky Mountain Trench near Canal Flats, British Columbia. Reprocessing of the LITHOPROBE seismic reflection line was conducted to improve resolution of upper-crustal features. Careful application of "conventional" processing techniques significantly improved the coherence of reflections from the first 6 s. A spatial semblance filter was applied to further enhance coherent signal, and residual-statics corrections were applied by cross correlation of unstacked data with semblance-filtered pilot traces.A near-basement reflection zone arising from Middle Cambrian strata is visible on an industry reflection profile at an approximate depth of 8 km beneath the Main Ranges. A similar reflection zone is imaged on the LITHOPROBE data at a depth of 11 km bsl but is interpreted as arising from Proterozoic strata. The autochthonous crystalline basement is interpreted as being below these layers and dipping about 2 °to the west. Geometric evidence is visible for several major thrust ramps involving the basal décollement and for an intermediate-level décollement that loses displacement into folds within the Porcupine Creek Anticlinorium. Reflections related to the Gypsum fault, the Redwall thrust, and the Lussier River normal fault are also imaged.
Comparison of trends of iceberg scour marks with iceberg trajectories and evidence of paleocurrent trends on Saglek Bank, northern Labrador Shelf
Authors: Todd B. J. , Lewis C. F. M. , Ryall P. J. C.
Published: June 2010

High-resolution seismic and sidescan sonar surveys on Saglek Bank indicate extensive areas of iceberg-scoured sea bottom and provide data for an analysis of 6075 iceberg scour marks in 537 samples, each of 0.25 km by 2.0 km area.The general trends of iceberg scours, measured on sidescan sonographs, are comparable to iceberg trajectories, which are mostly controlled by currents. On Saglek Bank, iceberg-scour and iceberg-drift directions are generally northwest–southeast.Straight scours predominate on the shelf edge, reflecting the influence of unidirectional oceanic (Labrador) currents. Bank-top scours are commonly curved, reflecting the influence of slower moving water more subject to the effects of rotary tidal currents and storms. This difference in dispersion of scour trends between the bank top and shelf edge is due to the relative strengths of variable tidal and storm-driven currents and unidirectional oceanic currents. Pack-ice forces may also influence iceberg movement.Modern icebergs scour the shelf to about 220 m water depth, locally to 280 m, and can change draft by about 25 m. Scarps in excess of 25 m vertical relief appear to redirect icebergs offslope or along slope.Relict scours were observed in the 220–300 m depth range and were differentiated from recent scours on the basis of greater width, discordant orientation, or advanced degree of degradation. Relict scours near water depths of 220 m are superimposed by modern scours and in shallower water are completely obliterated. Those scours remaining below 220 m show evidence of paleoceanographic conditions, which, in places, are similar to present conditions such as at northeast Saglek Bank. In other places, currents flowed in a different direction from those at present, as indicated by east–west scour trends in Okak Trough. Thus paleoscour directions may be useful in the reconstruction of paleocurrent trends.
Paleomagnetic study of the Ordovician Table Head Group, Port au Port Peninsula, Newfoundland
Authors: Hall Stuart A. , Evans Ian
Published: June 2010

A paleomagnetic study of the Ordovician Table Head Group in the Port au Port Peninsula of western Newfoundland reveals a simple two-component magnetization history comprising a reversely magnetized, stable southeasterly remanence with a, shallow to moderate inclination, and an unstable present-day overprint. Pole positions for the stable component, both with and without tectonic tilt correction, correspond with the Early to middle Ordovician pole positions for North America, suggesting this remanence is early. Although the nature of the geomagnetic field in the Ordovician is not well known, the polarity observed is consistent with that reported from other mid-Ordovician studies and appears to reflect a predominance of reverse polarity for this time interval. Evidence of significant rotation of any of the sites studied is absent, indicating that the continental margin in this region acted in an integral rather than a fragmented fashion during deformation.Previously published and new, but preliminary, results from the Early Ordovician St. George Group indicate the presence of two stable components of remanence. These components have similar south-southeasterly declinations but differ in inclination. The shallow to intermediate positive inclination component has a direction that is broadly compatible with Early Ordovician poles from North America. The shallow negative inclination component observed in rocks of similar age from other parts of western Newfoundland appears to be consistent with a later remagnetization of this unit.
Cordierite + spinel parageneses in pelitic gneiss from the contact aureoles of the Mistastin batholith (Quebec) and the Taylor Brook gabbro complex (Newfoundland)
Authors: Owen J. Victor
Published: June 2010

The contact aureoles of the Mistastin batholith and the Taylor Brook gabbro complex contain cordierite + spinel-bearing assemblages derived from quartz-, K-feldspar-, sillimanite-, garnet-, and biotite-bearing pelitic gneiss. Andalusite occurs locally. As a result of continuous, cordierite-forming reactions, garnet and biotite have recrystallized to relatively Fe-rich compositions compared with their counterparts outside the aureoles.Mosaics of fine-grained cordierite and spinel replace sillimanite and biotite throughout the Mistastin aureole. Similar assemblages and textures are preserved in metapelite in the outer part of the Taylor Brook aureole, where garnet adjacent to sillimanite is replaced by cordierite + spinel. The formation of spinel-free cordierite porphyroblasts by garnet-, sillimanite-, biotite-, and quartz-consuming reactions depleted metapelites in both aureoles in quartz, permitting the formation of the undersaturated assemblages. The undersaturated cordierite + spinel assemblages formed on a domainal scale (individually, a few hundred cubic millimetres in volume) and coexist metastably with saturated assemblages elsewhere in the same rock. Peak temperatures (700–750 °C) determined for both aureoles were insufficient to stabilize quartz + spinel parageneses owing to the low gahnite content of the oxide (ZnO < 2 wt.%).Metapelites in the innermost part of the Taylor Brook aureole appear to have been desilicified by the formation and fractionation of anatectic melt, yielding migmatitic rocks virtually devoid of quartz and K-feldspar. In contrast, migmatite in the inner part of the Mistastin aureole retains a quartz + two-feldspar mineralogy, so, as in the nonmigmatitic paragneiss, undersaturated assemblages are present only on a domainal scale.These aureole rocks demonstrate that undersaturated assemblages are not only characteristic of thermally- recrystallized low-grade pelites but also can occur in contact aureoles developed in granulite-facies paragneiss. Aluminous rocks can become undersaturated by subsolidus, quartz-consuming reactions yielding cordierite, or by the formation of anatectic liquids.
Genesis of terrestrial oncoids, Cayman Islands, British West Indies
Authors: Jones Brian
Published: June 2010

Terrestrial oncoids, up to 4.3 mm long, are common in sinkholes that penetrate the dolostones of the Oligocene–Miocene Bluff Formation on Grand Cayman and Cayman Brac. The vaguely laminated terrestrial oncoids, which generally lack a nucleus, are formed of detrital material (micrite, clays, dolomite), calcified filaments and spores, and insect fragments. The abundant, diverse assay of microorganisms includes six different types of filaments and five different types of spores, which can be attributed to fungi, algae, and (or) cyanobacteria. Thin mats of mucus are commonly associated with the microorganisms. The microorganisms contribute to the formation of the terrestrial oncoids by (i) calcification of the filaments and spores, (ii) trapping and binding detrital material, and (iii) binding with their mucus detrital material to the surface of the oncoids.Identification of terrestrial oncoids relies on (i) the recognition of a microbial assemblage, (ii) the demonstration that the microorganisms played an active role in the their formation, and (iii) evidence that they formed in a terrestrial setting. If the microorganisms cannot be recognized because of diagenetic changes, identification must rely on the overall texture of the rock and its stratigraphic setting. Recognition of terrestrial oncoids is important because it provides additional evidence that a succession has been subaerially exposed. Terrestrial oncoids also indicate that the strata in which they occur are close to an unconformity.