bluuebunny/crossref_metadata_2025 huggingface dataset:
Earliest high‐Ti volcanism on the Moon: 40Ar‐39Ar, Sm‐Nd, and Rb‐Sr isotopic studies of Group D basalts from the Apollo 11 landing site
Authors: Snyder Gregory A. , Hall Chris M. , Halliday Alex N. , Lee Der‐Chuen , Taylor Lawrence A.
Published: August 2012

Abstract High‐Ti basalts from the Apollo collections span a range in age from 3.87 Ga to 3.55 Ga. The oldest of these are the common Apollo 11 Group B2 basalts which yield evidence of some of the earliest melting of the lunar mantle beneath Mare Tranquillitatis. Rare Group D high‐Ti basalts from Mare Tranquillitatis have been studied in an attempt to confirm a postulated link with Group B2 basalts (Jerde et al., 1994). The initial Sr isotopic ratio of a known Group D basalt (0.69916 ± 3 at 3.85 Ga) lies at the lower end of the tight range for Group B2 basalts (87Sr/86Sr = 0.69920 to 0.69921). One known Group D basalt and a second postulated Group D basalt yield indistinguishable initial ∍Nd (1.2 ± 0.6 and 1.2 ± 0.3) and again lie at the lower end of the range for the Group B2 basalts from Apollo 11 (+2.0 ± 0.4 to +3.9 ± 0.6, at 3.85 Ga). A third sample has isotopic (87Sr/86Sr = 0.69932 ± 2; ∍Nd = 2.5 ± 0.4; at 3.59 Ga; as per Snyder et al., 1994b) and elemental characteristics similar to the Group A high‐Ti basalts returned from the Apollo 11 landing site.

Ages of 40Ar‐39Ar have been determined for one known Group D basalt and a second postulated Group D basalt using step‐heating with a continuous‐wave laser. Suspected Group D basalt, 10002, 1006, yielded disturbed age spectra on two separate runs, which was probably due to 39Ar recoil effects. Using the “reduced plateau age” method of Turner et al. (1978), the ages derived from this sample were 3898 ± 19 and 3894 ± 19 Ma. Three separate runs of known Group D basalt 10002, 116 yielded 40Ar/39Ar plateau ages of 3798 ± 9 Ma, 3781 ± 8 Ma, and 3805 ± 7 Ma (all errors 2σ). Furthermore, this sample has apparently suffered significant 40Ar loss either due to solar heating or due to meteorite impact. The loss of a significant proportion of 40Ar at such a time means that the plateau ages underestimate the “true” crystallization age of the sample. Modelling of this Ar loss yields older, “true” ages of 3837 ± 18, 3826 ± 16, and 3836 ± 14 Ma. These ages overlap the ages of Group B2 high‐Ti basalts (weighted average age = 3850 ± 20 Ma; range in ages = 3.80 to 3.90 Ga).

The combined evidence indicates that the Group D and B2 high‐Ti basalts could be coeval and may be genetically related, possibly through increasing degrees of melting of a similar source region in the upper mantle of the Moon that formed >4.2 Ga ago. The Group D basalts were melted from the source first and contained 3–5×more trapped KREEP‐like liquid than the later (by possibly only a few million years) Group B2 basalts. Furthermore, the relatively LREE‐ and Rb‐enriched nature of these early magmas may lend credence to the idea that the decay of heat‐producing elements enriched in the KREEP‐like trapped liquid of upper mantle cumulates, such as K, U, and Th, could have initiated widespread lunar volcanism.
Reflectance spectroscopy of interplanetary dust particles
Authors: Bradley J. P. , Keller L. P. , Brownlee D. E. , Thomas K. L.
Published: August 2012

Abstract Reflectance spectra were collected from chondritic interplanetary dust particles (IDPs), a polar micrometeorite, Allende (CV3) meteorite matrix, and mineral standards using a microscope spectrophotometer. Data were acquired over the 380–1100 nm wavelength range in darkfield mode using a halogen light source, particle aperturing diaphrams, and photomultiplier tube (PMT) detectors. Spectra collected from titanium oxide (Ti4O7), magnetite (Fe3O4), and Allende matrix establish that it is possible to measure indigenous reflectivities of micrometer‐sized (>5 μm in diameter) particles over the visible (VIS) wavelength range 450–800 nm. Below 450 nm, small particle effects cause a fall‐off in signal into the ultraviolet (UV). Near‐infrared (IR) spectra collected from olivine and pyroxene standards suggest that the ∼1 μm absorption features of Fe‐bearing silicates in IDPs can be detected using microscope spectrophotometry.

Chondritic IDPs are dark objects (<15% reflectivity) over the VIS 450–800 nm range. Large (>1 μm in diameter) embedded and adhering single mineral grains make IDPs significantly brighter, while surficial magnetite formed by frictional heating during atmospheric entry makes them darker. Most chondritic smooth (CS) IDPs, dominated by hydrated layer silicates, exhibit generally flat spectra with slight fall‐off towards 800 nm, which is similar to type CI and CM meteorites and main‐belt C‐type asteroids. Most chondritic porous (CP) IDPs, dominated by anhydrous silicates (pyroxene and olivine), exhibit generally flat spectra with a slight rise towards 800 nm, which is similar to outer P and D asteroids. The most C‐rich CP IDPs rise steeply towards 800 nm with a redness comparable to that of the outer asteroid object Pholus (Binzel, 1992). Chondritic porous IDPs are the first identified class of meteoritic materials exhibiting spectral reflectivities (between 450 and 800 nm) similar to those of P and D asteroids.

Although large mineral grains, secondary magnetite, and small particle effects complicate interpretation of IDP reflectance spectra, microscope spectrophotometry appears to offer a rapid, nondestructive technique for probing the mineralogy of IDPs, comparing them with meteorites, investigating their parent body origins, and identifying IDPs that may have been strongly heated during atmospheric entry.
Breccias resembling melt bombs from the Roter Kamm Crater
Authors: Degenhardt J. J. , Miller R. McG. , Reimold W. U. , Reid A. M.
Published: August 2012

Abstract Irregular, dark green to black, glassy‐looking boulders are locally common in the northwest portion of the rim of the Roter Kamm impact crater in southern Namibia. Their smooth surfaces, flow‐like textures, presence of folds, and their similarity to melt bombs have led to the interpretation that these are molten impact ejecta. However, the samples we have examined are all fine‐grained breccias composed of angular fragments that show no evidence of melting. Meltlike surface textures of these rim breccias are largely a consequence of surface wind polishing of fine‐grained rocks in a desert environment. These mono‐mict breccias were produced by impact‐related brecciation of Gariep sediments (carbonaceous, siliceous shales) previously modified by low‐grade Damaran metamorphism. Secondary quartz within the breccias is attributed to fluid activity that postdates the impact.
The Lueders, Texas, IAB iron meteorite with silicate inclusions
Authors: McCoy T. J. , Ehlmann A. J. , Benedix G. K. , Keil K. , Wasson J. T.
Published: August 2012

Abstract The Lueders iron meteorite with silicate inclusions was recovered as a single specimen of ∼35.4 kg in Shackelford County, Texas, in 1973 and recognized as a meteorite in 1993. Siderophile element concentrations indicate chemical classification as a low‐Ni IAB iron meteorite closely related to Landes; like Landes, it has a Cu content ∼4σ above the main IAB‐IIICD trend and therefore we also designate Lueders as an anomalous member of IAB. The metallic host is composed of equigranular kamacite but with a suggestion of octahedral structure and with a bandwidth of 1.4 mm, suggesting structural classification as a coarse octahedrite (Og). The meteorite contains ∼23 wt% of roughly millimeter to centimeter‐sized angular silicate inclusions. Classification as a IAB is confirmed by O isotopic analysis of silicate inclusions. These inclusions contain an assemblage rich in silicates, troilite and graphite; lack certain minor phases (e.g., daubreelite); and have angular shapes. A variety of processes (e.g., fragmentation, partial melting, reduction) appear to have played a significant role in the formation of Lueders and all IAB iron meteorites. Petrologic and chemical differences confirm that Lueders is not paired with the widely distributed Odessa meteorite.
Discovering research value in the Campo del Cielo, Argentina, meteorite craters
Authors: CASSIDY William A. , RENARD Marc L.
Published: August 2012

Abstract The Campo del Cielo meteorite crater field in Argentina contains at least 20 small meteorite craters, but a recent review of the field data and a remote sensing study suggest that there may be more. The fall occurred ∼4000 years ago into a uniform loessy soil, and the craters are well enough preserved so that some of their parameters of impact can be determined after excavation. The craters were formed by multi‐ton fragments of a type IA meteoroid with abundant silicate inclusions. Relative to the horizontal, the angle of infall was ∼9°. Reflecting the low angle of infall, the crater field is elongated with apparent dimensions of 3 × 18.5 km. The largest craters are near the center of this ellipse. This suggests that when the parent meteoroid broke apart, the resulting fragments diverged from the original trajectory in inverse relation to their masses and did not undergo size sorting due to atmospheric deceleration. The major axis of the crater field as we know it extends along N63°E, but the azimuths of infall determined by excavation of Craters 9 and 10 are N83.5°E and N75.5°E, respectively. This suggests that the major axis of the crater field is not yet well determined. The three or four largest craters appear to have been formed by impacts that disrupted the projectiles, scattering fragments around the outsides of the craters and leaving no large masses within them; these are relatively symmetrical in shape. Other craters are elongated features with multi‐ton masses preserved within them and no fragmentation products outside. There are two ways in which field research on the Campo del Cielo crater field is found to be useful. (1) Studies exist that have been used to interpret impact craters on planetary surfaces other than the Earth. This occurrence of a swarm of projectiles impacting at known angles and similar velocities into a uniform target material provides an excellent field site at which to test the applicability of those studies. (2) Individual craters at Campo del Cielo can yield the masses of the projectiles that formed them and their velocities, angles and azimuths of impact. From these data, there is a possibility to estimate parameters for the parent meteoroid at entry and, thus, learn enough about its orbit to judge whether or not it was compatible with an asteroidal origin. Preliminary indications are that it was. Campo del Cielo is a IA iron meteorite and Sikhote‐Alin, an observed fall, is a IIB iron meteorite in Wasson's classification. The Sterlitamak iron, also an observed fall, is a medium octahedrite in the Prior‐Hey classification. It would be interesting to compare their orbital parameters.
The inventory of interstellar materials available for the formation of the solar system
Authors: SANDFORD Scott A.
Published: August 2012

Abstract Tremendous progress has been made in the field of interstellar dust in recent years through the use of telescopic observations, theoretical studies, laboratory studies of analogs, and the study of actual interstellar samples found in meteorites. It is increasingly clear that the interstellar medium (ISM) contains an enormous diversity of materials created by a wide range of chemical and physical processes. This understanding is a far cry from the picture of interstellar materials held as recently as two decades ago, a picture which incorporated only a few generic types of grains and few molecules.

In this paper, I attempt to review some of our current knowledge of the more abundant materials thought to exist in the ISM. The review concentrates on matter in interstellar dense molecular clouds since it is the materials in these environments from which new stars and planetary systems are formed. However, some discussion is reserved for materials in circumstellar environments and in the diffuse ISM. The paper also focuses largely on solid materials as opposed to gases since solids contain a major fraction of the heavier elements in clouds and because solids are most likely to survive incorporation into new planetary systems in identifiable form. The paper concludes with a discussion of some of the implications resulting from the recent growth of our knowledge about interstellar materials and also considers a number of areas in which future work might be expected to yield important results.
Impact melt dikes in the Sudbury multi‐ring basin (Canada): Implications from uranium‐lead geochronology on the Foy Offset Dike
Authors: OSTERMAN Markus , SCHÄRER Urs , DEUTSCH Alexander
Published: August 2012

Abstract To investigate the origin of Offset Dikes and their age relationships to major impact generated lithologies in the Sudbury multi‐ring impact structure, such as the Main Mass of the Sudbury “Igneous” Complex, zircon and baddeleyite were dated by the U‐Pb chronometer. The rocks analysed are one diorite and two quartz diorites from inside the Foy Offset, one quartz diorite from the contact zone, and two country rock samples collected at 10 and 30 m distances from the contact within the Levack Gneiss Complex. The 21 analysed zircon and baddeleyite fractions yield a crystallization age of 1852 +4/‐3 (2σ) Ma for the accessory minerals in the Foy Offset Dike and an age of 2635 ± 5 Ma for the shocked Levack country rock, in which zircons show significant shock effects (multiple sets of planar fractures), in contrast to the totally unshocked zircons of the Offset Dike. Within given errors, the new age of 1852 Ma is identical to the pooled 1850 ± 1 Ma U‐Pb age determined by Krogh et al. (1984) as the crystallization age of accessory phases in different lithologies of the Sudbury “Igneous” Complex, which has been interpreted to represent the coherent impact melt sheet of the Sudbury Structure. This excellent agreement of the ages substantiates that emplacement of the Offset Dikes occurred coevally with the formation of the impact melt sheet. Total absence of inherited zircons in the central part of the Foy Offset indicates melting of the precursor material at temperatures well above 1700 °C, which emphasizes the origin of the dike lithologies by impact melting.
The Meteoritical Bulletin, No. 80, 1996 July
Authors: Grossman Jeffrey N.
Published: August 2012

Abstract— The Meteoritical Bulletin No. 80 lists data for 178 meteorites. Noteworthy are 3 HED meteorites (ALH 88102, Hammadah al Hamra (HaH) 059, and Monticello); 3 ureilites (HaH 064, HaH 126, and Dar al Gani (DaG) 084); 4 irons (Baygorria (IAB), Ste. Croix (IIIAB), Sargiin Gobi (IAB), and Tarahumara (IIE)); an unusual metal‐rich meteorite (Vermillion); 8 carbonaceous chondrites (HaH 043 (C03), HaH 073 (C4), DaG 055 (C3) and 5 C03 chondrites (probably paired) from DaG); an R chondrite (DaG 013); and 6 unequilibrated ordinary chondrites (ALH 88105 (L3), Camel Donga 016 (L3), HaH 093 (LL3.9), HaH 096 (LL(L)3), Richfield (LL3.7), and Sarir Quattusah (LL(L)3)). Three recent falls of ordinary chondrites (Coleman (LL5), St. Robert (H5), and Tsukuba (H5‐6)) are described.
Mineralogy, chemistry, and oxygen isotopes of refractory inclusions from stratospheric interplanetary dust particles and micrometeorites
Authors: GRESHAKE Ansgar , BISCHOFF Adolf , HOPPE Peter
Published: August 2012

Abstract— Calcium, aluminum‐rich inclusions (CAIs) are characteristic components in carbonaceous chondrites. Their mineralogy is dominated by refractory oxides and silicates like corundum, perovskite, spinel, hibonite, melilite, and Ca‐pyroxene, which are predicted to be the first phases to have condensed from the cooling solar nebula. Allowing insights into processes occurring in the early solar system, CAIs in carbonaceous and ordinary chondrites were studied in great detail, whereas only a few refractory inclusions were found and studied in stratospheric interplanetary dust particles (IDPs) and micrometeorites.

This study gives a summary of all previous studies on refractory inclusions in stratospheric IDPs and micrometeorites and will present new data on two Antarctic micrometeorites. The main results are summarized as follows: (a) Eight stratospheric IDPs and six micrometeorites contain Ca, Al‐rich inclusions or refractory minerals. The constituent minerals include spinel, perovskite, fassaite, hibonite, melilite, corundum, diopside and anorthite. (b) Four of the seven obtained rare‐earth‐element (REE) patterns from refractory objects in stratospheric IDPs and micrometeorites are related to Group III patterns known from refractory inclusions from carbonaceous chondrites. A Group II related pattern was found for spinel and perovskite in two micrometeorites. The seventh REE pattern for an orthopyroxene is unique and can be explained by fractionation of Gd, Lu, and Tb at highly reducing conditions. (c) The O‐isotopic compositions of most refractory objects in stratospheric IDPs and micrometeorites are similar to those of constituents from carbonaceous chondrites and fall on the carbonaceous chondrites anhydrous minerals mixing line. In fact, in most cases, in terms of mineralogy, REE pattern and O‐isotopic composition of refractory inclusions in stratospheric IDPs and micrometeorites are in good agreement with a suggested genetic relation of dust particles and carbonaceous chondrites. Only in the case of one Antarctic micrometeorite does the REE pattern obtained for an orthopyroxene point to a link of this particle to enstatite chondrites.
The thermal and radiation exposure history of lunar meteorites
Authors: BENOIT Paul H. , SEARS Derek W. G. , SYMES Steven J. K.
Published: August 2012

Abstract— We have measured the natural and induced thermoluminescence (TL) of seven lunar meteorites in order to examine their crystallization, irradiation, and recent thermal histories. Lunar meteorites have induced TL properties similar to Apollo samples of the same provenance (highland or mare), indicating similar crystallization and metamorphic histories. MacAlpine Hills 88104/5 has experienced the greatest degree of impact/regolith processing among the highland‐dominated meteorites. The basaltic breccia QUE 94281 is dominated by mare component but may also contain a significant highland component. For the mare‐dominated meteorites, EET 87521 may have a significant highland impact‐melt component, while Asuka 881757 and Y‐793169 have been heavily shocked. The thermal history of Y‐793169 included slow cooling, either during impact processing or during its initial crystallization. Our natural TL data indicate that most lunar meteorites have apparently been irradiated in space a few thousand years, with most <15,000 a. Elephant Moraine 87521 has the lowest irradiation exposure time, being <1,000 a. Either the natural TL of ALHA81005, Asuka 881757 and Y‐82192 was only partially reset by lunar ejection or these meteorites were in small perihelia orbits (≤0.7 AU).
Exposure history of lunar meteorites Queen Alexandra Range 93069 and 94269
Authors: NISHIIZUMI K. , CAFFEE M. W. , JULL A. J. T. , REEDY R. C.
Published: August 2012

Abstract— Cosmic‐ray produced 14C (t1/2 = 5730 years), 36Cl (3.01 × 105 years), 26Al (7.05 × 105 years), and 10Be (1.5 × 106 years) in the recently discovered lunar meteorites Queen Alexandra Range 93069 (QUE 93069) and 94269 (QUE 94269) were measured by accelerator mass spectrometry. The abundance pattern of these four cosmogenic radionuclides and of noble gases indicates QUE 93069 and QUE 94269 were a paired fall and were exposed to cosmic rays near the surface of the Moon for at least several hundred million years before ejection. After the meteorite was launched from the Moon, where it had resided at a depth of 65–80 g/cm2, it experienced a short transition time, ∼20–50 ka, before colliding with the Earth. The terrestrial age of the meteorite is 5–10 ka. Comparison of the cosmogenic nuclide concentrations in QUE 93069/94269 and MAC 88104/88105 clearly shows that these meteorites were not ejected by a common event from the Moon.
Mineralogy and geochemistry of lunar meteorite Queen Alexandra Range 93069
Authors: KOEBERL Christian , KURAT Gero , BRANDSTÄTTER Franz
Published: August 2012

Abstract— Queen Alexandra Range (QUE) 93069 is a glass‐rich regolith breccia derived from the lunar highlands. The high abundance of glassy fragments, the presence of agglutinates, the small size of all mineral and glass fragments, the presence of mostly melt rocks, and the low abundance of pristine lunar crustal rocks, all indicate that QUE 93069 is derived from a mature regolith. This conclusion is also supported by its high siderophile element content. The most common mafic mineral is pyroxene, with compositions that indicate derivation from ferroan ANT suite rocks. Rare gabbro differentiation products may be indicated by the presence of silica, fayalitic olivine, and one pyroxferroite grain. Lithic fragments are mostly meta‐melt rocks of ANT composition. The glass compositions are dominated by troctolitic anorthosite compositions, followed by gabbroic anorthosite and noritic anorthosite. Most glasses are ol‐normative in composition. Some rare basic glasses of noritic composition were observed. Glass fragments and matrix glasses are alkali‐poor, except for some rare alkali‐rich shards. The bulk chemical composition of QUE 93069, as well as the rare‐earth‐element (REE) abundance pattern, is very similar to that of other highlands meteorites, such as MAC 88105 and Y‐86032 and to average lunar highlands crust. One small porous clast was found to be very rich in volatile elements, as well as in most lithophile and siderophile elements. As this sample also contains abundant sulfides, the enrichments could be related to element mobilization and redistribution by volatile sulfur species.
Delayed metastasis of ocular squamous cell carcinoma following treatment in five horses
Authors: Mair T. S. , Sherlock C. E. , Pearson G. R.
Published: August 2012

Identification of regional and/or distant metastasis following treatment and local resolution of primary ocular squamous cell carcinoma (SCC) was observed in 5 horses. In all cases, identification of metastasis occurred at least 18 months following treatment of the primary ocular lesions. In 3 cases, invasion of blood or lymphatic vessels by neoplastic cells was identified in the excisional biopsies of the primary tumour. Two horses developed SCC at 2 or more separate sites. At the time metastases were identified, there was no evidence of local recurrence of the ocular tumour in any of the horses. These cases confirm the importance of long‐term monitoring of horses for metastatic disease following treatment of ocular SCC even in the absence of local recurrence.
Treatment of peri‐implantitis using multiple applications of chlorhexidine chips: a double‐blind, randomized multi‐centre clinical trial
Authors: Machtei Eli E. , Frankenthal Shai , Levi Guy , Elimelech Rina , Shoshani Eyal , Rosenfeld Olivia , Tagger‐Green Nirit , Shlomi Benjamin
Published: August 2012

Background

Universal strategies for managing peri‐implantitis are yet to be adopted. The aim of this study is to examine a protocol of intensive application of chlorhexidine containing chips in sites with peri‐implantitis.

Materials and Methods

This multi‐centre, randomized, double‐blind, parallel, two‐arm clinical trial included 60 patients (77 implants) with probing depth (PD) 6–10 mm and bone loss ≥2 mm around 1–2 implants. One to two weeks following SRP, baseline measurements were made followed by implants' debridement. Patients were randomized to receive matrix chips (MatrixC) or chlorhexidine Chips (PerioC). Measurements and chips placement were repeated at weeks 2, 4, 6, 8, 12 and 18. At 6 months, patients returned for final examination.

Results

Probing depth reduction was greater in the PerioC (2.19 ± 0.24 mm) compared with MatrixC (1.59 ± 0.23 mm), p = 0.07. Seventy percentage of the implants in the PerioC and 54% in the MatrixC had PD reduction ≥ 2 mm. Likewise, 40% of the sites (PerioC) and 24% (MatrixC) had PD reduction ≥ 3 mm. Clinical attachment level gains for both groups were significant; however, the changes in the PerioC group were significantly greater than in MatrixC [2.21 ± 0.23 mm. and 1.56 ± 0.25 mm respectively, p = 0.05]. Bleeding on probing was reduced by half in both groups.

Conclusion

Frequent placement of PerioC and MatrixC together with implants debridement resulted in a substantial improvement in sites with peri‐implantitis. Further studies will be required to fully appreciate the mechanism of this treatment.
Host plant volatiles responsible for the invasion of Stenotus rubrovittatus (Heteroptera: Miridae) into paddy fields
Authors: Hori M. , Namatame M.
Published: August 2012

We investigated the attractiveness of synthetic volatile blends or individual volatiles of flowering rice panicles or flowering Scirpus juncoides spikelets to the sorghum plant bug Stenotus rubrovittatus (Matsumura). None of the individual chemicals tested attracted either sex of the bug. Synthetic volatile blends of flowering rice panicles composed of geranyl acetone, β‐caryophyllene, n‐decanal, methyl salicylate, β‐elemene and n‐tridecene attracted females. The synthetic blend of volatiles was just as attractive as natural flowering rice panicles to females. Other synthetic blends did not attract the bug. We sampled headspace volatiles from flowering S. juncoides spikelets with solid‐phase microextraction and analysed them using gas chromatography–mass spectrometry. The main volatile emitted from S. juncoides was β‐caryophyllene, one of the major volatile components of flowering rice panicles. β‐Elemene was a common volatile found in flowering rice panicles and flowering S. juncoides spikelets. Therefore, we investigated the attractiveness of synthetic blends of flowering rice panicles and S. juncoides spikelets composed of β‐caryophyllene and β‐elemene. The synthetic blend of flowering S. juncoides spikelets significantly attracted males but not females. The synthetic blend of flowering rice panicles composed of β‐caryophyllene and β‐elemene did not attract either sex. These results suggest that β‐caryophyllene and β‐elemene are common active compounds responsible for attractiveness of flowering rice panicles and S. juncoides spikelets although some of the other volatile components act synergistically with these two compounds in natural plant odours.
Life tables of Bactrocera cucurbitae (Diptera: Tephritidae): with an invalidation of the jackknife technique
Authors: Huang Y.‐B. , Chi H.
Published: August 2012

Life table gives the most comprehensive description on the survival, stage differentiation and reproduction of a population and is thus the most important basis of population ecology and pest management. In this study, we constructed life tables for Bactrocera cucurbitae on cucumber (Cucumis sativus L.) in the laboratory and under simulated field conditions. To assess the variability of the life tables, we carried out two experiments under each treatment. Means, variances and standard errors of life table parameters were estimated for each of the two experiments by using the jackknife technique. At 25°C, the intrinsic rates of increase (r) found for the two experiments were 0.1354 and 0.1002 per day, and the net reproductive rates (R0) were 206.3 and 66.0 offspring, respectively. For cucumbers kept in the field and covered with leaves, the r and R0 for the two experiments were 0.0935 and 0.0909 per day, and 17.5 and 11.4 offspring, respectively. However, if cucumbers were kept in the field but were not covered, the r and R0 for the two experiments were 0.1043 and 0.0904 per day, and 27.7 and 10.1 offspring, respectively. Our results revealed significant variability between the experiments under both laboratory and field conditions; this variability should be taken into consideration in the data collection and application of life tables. However, our mathematical analysis shows that the application of the jackknife technique will result in biologically unrealistic R0,i‐pseudo and consequently overestimation of the variance of R0. According to our analysis, we suggest that the jackknife technique should not be used for the estimation of variability of the net reproductive rate.
Silicon Suppresses Fusarium Wilt Development in Banana Plants
Authors: Fortunato Alessandro Antonio , Rodrigues Fabrício Ávila , Baroni Júlio Cezar Parpaiola , Soares Gustavo César Barbosa , Rodriguez Miguel Angel Dita , Pereira Olinto Liparini
Published: August 2012

This study aimed to determine the effect of silicon (Si) in reducing the symptoms of Fusarium wilt, caused by Fusarium oxysporum f. sp. cubense (Foc), on banana plants. Banana seedlings of Grand Nain (resistant) and Maçã (susceptible) were grown in plastic trays amended with 0 (−Si) or 0.39 g Si (+Si) per kg of soil and inoculated with Foc at 60 days after transplanting. The Si concentration in the roots and rhizome‐pseudostem significantly increased by 30.26 and 58.82%, respectively, for the +Si treatment compared with −Si treatment. The Si concentration in the roots and rhizome‐pseudostem of Grand Nain plants was, respectively, 11.57 and 37.04% greater than that found in Maçã. The +Si plants showed a reduction of 12.37, 49.81, 51.87 and 20.39%, respectively, for the area under reflex leaf symptoms progress curve, the area under root symptoms progress curve, the area under disease progress curve and the area under asymptomatic fungal colonization of tissue progress curve compared with ‐Si plants. The area under darkening of rhizome‐pseudostem progress curve (AUDRPPC) of Maçã significantly increased by 15.98% for the −Si treatment in comparison with the +Si treatment. For the +Si treatment, the AUDRPPC of the plants from the Maçã cultivar significantly decreased by 20.59% in comparison with the plants from the Grand Nain cultivar. The area under relative lesion length progress curve (AURLLPC) of the plants from the Maçã cultivar significantly decreased by 41.54% for the +Si treatment in comparison with the −Si treatment. There was no significant difference between the ‐Si and +Si treatments in the AUDRPPC and AURLLPC of Grand Nain. For the +Si treatment, the AURLLPC of Grand Nain significantly decreased by 9.23% in comparison with Maçã. There was no significant difference between the Grand Nain and Maçã for the AUDRPPC and AURLLPC in the −Si treatment. The findings of this study show that supplying Si to banana plants, especially to a susceptible cultivar to Foc, had a great potential in reducing the intensity of Fusarium wilt and may play a key role in disease management when banana plants are cultivated in Si‐deficient soils infested by this pathogen.
Retracted: Dynamic complex formation between HD‐GYP, GGDEF and PilZ domain proteins regulates motility in Xanthomonas campestris
Authors: Ryan Robert P. , McCarthy Yvonne , Kiely Patrick A. , O'Connor Rosemary , Farah Chuck S. , Armitage Judith P. , Dow J. Maxwell
Published: August 2012

RpfG is a member of a class of wide spread bacterial two‐component regulators with an HD‐GYP cyclic di‐GMP phosphodiesterase domain. In the plant pathogen Xanthomonas campestris, RpfG together with the sensor kinase RpfC regulates multiple factors as a response to the cell‐to‐cell Diffusible Signalling Factor (DSF). A dynamic physical interaction of RpfG with two diguanylate cyclase (GGDEF) domain proteins controls motility. Here we show that, contrary to expectation, regulation of motility by the GGDEF domain proteins does not depend upon their cyclic di‐GMP synthetic activity. Furthermore we show that the complex of RpfG and GGDEF domain proteins recruits a specific PilZ domain ‘adaptor’ protein, and this complex then interacts with the pilus motor proteins PilU and PiIT. The results support a model in which DSF signalling influences motility through the highly regulated dynamic interaction of proteins that affect pilus action. A specific motif that we identify to be required for HD‐GYP domain interaction is conserved in a number of GGDEF domain proteins, suggesting that regulation via interdomain interactions is of broad relevance.
Iron and pH‐responsive FtrABCD ferrous iron utilization system of Bordetella species
Authors: Brickman Timothy J. , Armstrong Sandra K.
Published: August 2012

A putative operon encoding an uncharacterized ferrous iron transport (FtrABCD) system was previously identified in cDNA microarray studies. In growth studies using buffered medium at pH values ranging from pH 6.0 to 7.6, Bordetella pertussis and Bordetella bronchiseptica FtrABCD system mutants showed dramatic reductions in growth yields under iron‐restricted conditions at pH 6.0, but had no growth defects at pH 7.6. Supplementation of culture medium with 2 mM ascorbate reductant was inhibitory to alcaligin siderophore‐dependent growth at pH 7.6, but had a neglible effect on FtrABCD system‐dependent iron assimilation at pH 6.0 consistent with its predicted specificity for ferrous iron. Unlike Bordetella siderophore‐dependent and haem iron transport systems, and in agreement with its hypothesized role in transport of inorganic iron from periplasm to cytoplasm, FtrABCD system function did not require the TonB energy transduction complex. Gene fusion analysis revealed that ftrABCD promoter activity was maximal under iron‐restricted growth conditions at acidic pH. The pH of human airway surface fluids ranges from pH 5.5 to 7.9, and the FtrABCD system may supply ferrous iron necessary for Bordetella growth in acidic host microenvironments in which siderophores are ineffective for iron retrieval.
Design of Radiation Tolerant Nanostructured Metallic Multilayers
Authors: Zhang X. , Fu E. G. , Li Nan , Misra A. , Wang Y.-Q. , Shao L. , Wang H.
Published: August 2012

We review He ion induced radiation damage in several metallic multilayer systems, including Cu/V, Cu/Mo, Fe/W, and Al/Nb up to a peak dose of several displacements per atom (dpa). Size dependent radiation damage is observed in all systems. Nanolayer composites can store a very high concentration of He. Layer interfaces promote the recombination of opposite type of point defects and hence reduce the accumulative defect density, swelling, and lattice distortion. Interfaces also alleviate radiation hardening substantially. The chemical stability of interfaces is an important issue when considering the design of radiation tolerant nanolayer composites. Immiscible and certain miscible systems possess superior stability against He ion irradiation. Challenge and future directions are briefly discussed.
Nonlinear Stress–Strain Characterization of Cast Iron Used to Manufacture Pipes for Water Supply
Authors: Rajani Balvant
Published: August 2012

The stress–strain response of cast iron under tension or compression is nonlinear. This paper examines how the hyperbolic constitutive law can be applied to characterize nonlinear stress–strain behavior of cast iron used in water supply networks. Procedures are described to obtain parameters of the hyperbolic constitutive law from either the response (data) obtained from simple uniaxial tensile and compressive tests or from bending tests. To demonstrate its applicability, this hyperbolic constitutive law is first applied to data obtained from uniaxial tensile and compressive tests conducted by Schlick and Moore (1936, “Strength and Elastic Properties of Cast Iron in Tension, Compression, Flexure, and Combined Tension and Flexure,” Bulletin 127, Iowa Engineering Experiment Station, Ames, IA). In addition, an approach to extract parameters for the hyperbolic constitutive law from bending (beam and pipe rings) tests is proposed and subsequently applied to tests conducted by Talbot (1908, “Tests of Cast-Iron and Reinforced Concrete Culvert Pipe,” Bulletin No. 22, University of Illinois, Urbana, IL). This latter approach is attractive for practical purposes because the test set up is simple and the test coupons are very easy to prepare. The hyperbolic constitutive law in conjunction with maximum normal strain theory as proposed by St. Venant (Collins, J. A., 1993, Failure of Materials in Mechanical Design: Analysis, Prediction, Prevention, John Wiley, New York, NY) was also used to predict failure loads.
Atomic layer deposition of Ti-HfO2 dielectrics
Authors: Werner Matthew , King Peter J. , Hindley Sarah , Romani Simon , Mather Sean , Chalker Paul R. , Williams Paul A. , van den Berg Jakob A.
Published: August 2012

Titanium-doped hafnium oxide films, TixHf1−xO2−δ, have been deposited with a Ti content of x = 0.1 and x = 0.5, by atomic layer deposition. The TixHf1−xO2−δ growth rate is lower compared with the growth rates of the individual binary oxides; however, the composition of the films is unaffected by the reduced growth rate. An 850  °C spike anneal and a 500  °C 30 min furnace anneal were performed, and the resulting film composition and structure was determined using medium energy ion scattering, x-ray diffraction, and transmission electron microscopy. The Ti0.1Hf0.9O2−δ films readily crystallize into a monoclinic phase during both types of annealing. By contrast, the Ti0.5Hf0.5O2−δ films remain amorphous during both annealing processes. Electrical characterization of the as-deposited Ti0.1Hf0.9O2−δ films yielded a dielectric constant of 20, which is slightly higher than undoped HfO2 films. The as-deposited Ti0.5Hf0.5O2−δ films showed a significant increase in dielectric constant up to 35. After a 500  °C 30 min anneal, the dielectric constant reduced slightly to 27. The leakage current density of the amorphous film remains relatively unaffected at 8.7×10−7 A/cm2 at −1 MV/cm, suggesting this composition/heat treatment is a candidate for future device dielectrics.
Biological effect of dose distortion by fiducial markers in spot‐scanning proton therapy with a limited number of fields: A simulation study
Authors: Matsuura Taeko , Maeda Kenichiro , Sutherland Kenneth , Takayanagi Taisuke , Shimizu Shinichi , Takao Seishin , Miyamoto Naoki , Nihongi Hideaki , Toramatsu Chie , Nagamine Yoshihiko , Fujimoto Rintaro , Suzuki Ryusuke , Ishikawa Masayori , Umegaki Kikuo , Shirato Hiroki
Published: August 2012

Purpose:

In accurate proton spot‐scanning therapy, continuous target tracking by fluoroscopic x ray during irradiation is beneficial not only for respiratory moving tumors of lung and liver but also for relatively stationary tumors of prostate. Implanted gold markers have been used with great effect for positioning the target volume by a fluoroscopy, especially for the cases of liver and prostate with the targets surrounded by water‐equivalent tissues. However, recent studies have revealed that gold markers can cause a significant underdose in proton therapy. This paper focuses on prostate cancer and explores the possibility that multiple‐field irradiation improves the underdose effect by markers on tumor‐control probability (TCP).

Methods:

A Monte Carlo simulation was performed to evaluate the dose distortion effect. A spherical gold marker was placed at several characteristic points in a water phantom. The markers were with two different diameters of 2 and 1.5 mm, both visible on fluoroscopy. Three beam arrangements of single‐field uniform dose (SFUD) were examined: one lateral field, two opposite lateral fields, and three fields (two opposite lateral fields + anterior field). The relative biological effectiveness (RBE) was set to 1.1 and a dose of 74 Gy (RBE) was delivered to the target of a typical prostate size in 37 fractions. The ratios of TCP to that without the marker (TCPr) were compared with the parameters of the marker sizes, number of fields, and marker positions. To take into account the dependence of biological parameters in TCP model, α/β values of 1.5, 3, and 10 Gy (RBE) were considered.

Results:

It was found that the marker of 1.5 mm diameter does not affect the TCPs with all α/β values when two or more fields are used. On the other hand, if the marker diameter is 2 mm, more than two irradiation fields are required to suppress the decrease in TCP from TCPr by less than 3%. This is especially true when multiple (two or three) markers are used for alignment of a patient.

Conclusions:

It is recommended that 1.5‐mm markers be used to avoid the reduction of TCP as well as to spare the surrounding critical organs, as long as the markers are visible on x‐ray fluoroscopy. When 2‐mm markers are implanted, more than two fields should be used and the markers should not be placed close to the distal edge of any of the beams.
Radiation therapy effects on white matter fiber tracts of the limbic circuit
Authors: Nazem‐Zadeh Mohammad‐Reza , Chapman Christopher H. , Lawrence Theodore L. , Tsien Christina I. , Cao Yue
Published: August 2012

Purpose

: To segment fiber tracts in the limbic circuit and to assess their sensitivity to radiation therapy (RT).

Methods:

Twelve patients with brain metastases who had received fractionated whole brain radiation therapy to 30 Gy or 37.5 Gy were included in the study. Diffusion weighted images were acquired pre‐RT, at the end of RT, and 1‐month post‐RT. The fornix, corpus callosum, and cingulum were extracted from diffusion weighted images by combining fiber tracking and segmentation methods based upon characteristics of the fiber bundles. Cingulum was segmented by a seed‐based tractography, fornix by a region of interests (ROI)‐based tractography, and corpus callosum by a level‐set segmentation algorithm. The radiation‐induced longitudinal changes of diffusion indices of the structures were evaluated.

Results:

Significant decreases were observed in the fractional anisotropy of the posterior part of the cingulum, fornix, and corpus callosum from pre‐RT to end of RT by –14.0%, –12.5%, and –5.2%, respectively (p < 0.001), and from pre‐RT to 1‐month post‐RT by –11.9%, –12.8%, and –6.4%, respectively (p < 0.001). Moreover, significant increases were observed in the mean diffusivity of the corpus callosum and the posterior part of the cingulum from pre‐RT to end of RT by 6.8% and 6.5%, respectively, and from pre‐RT to 1‐month post‐RT by 8.5% and 6.3%, respectively. The increase in the radial diffusivity primarily contributed to the significant decrease in the fractional anisotropy, indicating that demyelination is the predominant radiation effect on the white matter structures.

Conclusions:

Our findings indicate that the fornix and the posterior part of the cingulum are significantly susceptible to radiation damage. We have developed robust computer‐aided semiautomatic segmentation and fiber tracking tools to facilitate the ROI delineation of critical structures, which is important for assessment of radiation damage in a longitudinal fashion.
Lenz's Law Demonstration Using an Ultrasound Position Sensor
Authors: Fodor Petru S. , Peppard Tara
Published: August 2012

One of the very popular demonstrations used in introductory physics courses to illustrate Lenz's law is the “slowly falling magnet.” In its simplest version it requires only a powerful cylindrical magnet and a metal tube, typically of copper or aluminum. When dropped in the tube the magnet takes significantly longer to reach the other end than a geometrically similar but nonmagnetic object. This demonstration has been adapted for use in large classes using a camera to monitor the magnet as it approaches the end of the tube.1 Small versions that can be used for hands-on experiments also have been developed2 or are available commercially.3 This classical demonstration in its various forms almost never fails to impress first-time viewers.
Speed of Sound Versus Temperature Using PVC Pipes Open at Both Ends
Authors: Bacon Michael E.
Published: August 2012

In this paper we investigate the speed of sound in air as a function of temperature using a simple and inexpensive apparatus. For this experiment it is essential that the appropriate end corrections be taken into account. In a recent paper1 the end corrections for 2-in i.d. (5.04-cm) PVC pipes open at both ends were investigated. The air column resonance was excited using a paddle as in Blue Man Group® pipes.2 The “open end” end correction is given by 0.6133r in accordance with recent experiments3 and detailed theoretical calculations.4 This correction amounted to 1.56 cm for the 2-in PVC pipe used. However, the paddle end correction was found to be influenced by the transient position of the paddle during the excitation process. The paddle end correction was found to be 1.94 cm.
Fukushima Daiichi Accident and Its Radiological Impact on the Environment
Authors: Bevelacqua J. J.
Published: August 2012

The Fukushima Daiichi nuclear accident is a topic of current media and public interest. It provides a means to motivate students to understand the fission process and the barriers that have been designed to prevent the release of fission products to the environment following a major nuclear power reactor accident. The Fukushima Daiichi accident further encourages a discussion of the effect of fission products upon the environment, including the resulting contamination of air, water, soil, animals, fish, milk, and crops. Accident-generated radiation levels that caused the evacuation of people 20–30 km from the facility further serve to foster student interest and desire to understand the science associated with the Fukushima Daiichi accident.
Counterintuitive Behavior in Mechanical Networks
Authors: Peters Sarah , Vondracek Mark
Published: August 2012

Almost all introductory physics classes will, at some point, include springs and elastic forces. When studying such topics, it is interesting to consider the spring system shown in Fig. 1. In this system, two identical springs are arranged with the top of one spring anchored to the ceiling and the bottom of the second spring attached to a hanging weight. The two springs are then connected by a “middle” string, c. There are two other strings that are not tensioned (strings d and b), one connecting the ceiling and the bottom spring, and the other connecting to the hanging weight and the top spring. As indicated in Fig. 1, these two “support” strings have some slack in them.
Human Subjects Research and the Physics Classroom
Authors: Kubitskey Beth W. , Thomsen Marshall
Published: August 2012

Physics Education Research is a form of social science research in that it uses human subjects. As physicists we need to be aware of the ethical and legal ramifications of performing this research, taking into account the fundamental differences between working with substances and working with people. For several decades, the federal government has regulated research involving human subjects. With current procedures, a proposal soliciting federal funds for a research project involving human subjects will be flagged by the applicants institution and checked for compliance with appropriate regulations. However, there is a large body of Physics Education Research that is not federally funded and thus may not be flagged. Nevertheless, there are ethical standards that apply to this research. This paper outlines the preliminary considerations for conducting such research.
Falling PC Solitaire Cards: An Open-Inquiry Approach
Authors: González-Espada Wilson J.
Published: August 2012

Many of us have played the PC Solitaire game that comes as standard software in many computers. Although I am not a great player, occasionally I win a game or two. The game celebrates my accomplishment by pushing the cards forward, one at a time, falling gracefully in what appears to look like a parabolic path in a drag-free environment. One day, as I was watching this progression, I asked myself what is the downward acceleration of the playing cards. Could the game programmer have used a realistic value of Earth's acceleration due to gravity? It occurred to me that this could be an excellent open-inquiry activity for high school or introductory college physics students!