495 research outputs found
Caratteri geomorfologici della fascia costiera compresa tra la foce del fiume Albegna, la Laguna di Orbetello ed Ansedonia
No full textLa fascia costiera compresa tra la foce del Fiume Albegna e il promontorio di Ansedonia è una costa mista la cui genesi è stata dominata prevalentemente da processi erosivi in corrispondenza del promontorio del M. Argentario e di Ansedonia e da processi deposizionali nei cordoni litorali limitrofi. La crescita dei cordoni litorali è fortemente condizionata dagli apporti fluviali dell’Albegna a nord e del Fiora a sud. L’analisi geomorfologica ha permesso di individuare le varie tappe dell’evoluzione costiera e della genesi della laguna verificatesi durante l’Olocene. Sono stati individuati numerosi paleoalvei dell’Albegna che hanno creato degli apparati deltizi sia prima della genesi dei cordoni che successivamente. La massima ingressione olocenica ha generato una scarpata di erosione che ha interessato, terrazzandoli, depositi di conoide alluvionale, fluviali, detritici ed eolici deposti durante l’ultima fase fredda pleistocenica. Terrazzi minori associati alla divagazione laterale di meandri ad ampio raggio di curvatura e paleoalvei caratterizzano il bordo settentrionale della pianura dell’Albegna
The growth of the Chianti Ridge: progressive unconformities and depositional sequences in the S. Barbara Basin (Upper Valdarno, Italy)
No full textThe Chianti Ridge, elongated in a NW-SE direction, separates the Upper Valdarno from the Siena Basins. It is made of Macigno and
Scaglia Toscana Fms. belonging to the Tuscan Nappe that underlies the Ligurian Units. Inside the Upper Valdarno basin three main
synthems have been identified, separated by major unconformities; from the bottom: 1. Castelnuovo synthem, subdivided into
Spedalino and Meleto subsynthems, 2. Montevarchi synthem and 3. Bucine synthem. The Spedalino subsynthem, that unconformably
lies over the pre-Pliocene bedrock, is made up of thin and laterally discontinuous coarse gravels. The Meleto subsynthem, commonly
referred to a lacustrine environment, is made of alluvial plain lithofacies, including channel, crevasse splay and swamp depositional
systems where a Taxodium forest developed and peat accumulated. Close to the western margin of the basin these subsynthems are
tilted up to 60°. The Montevarchi synthem, mainly made of sands and gravels accumulated inside a wide braidplain, and lies
unconformably over the previous units. This synthem is tilted eastward up to 20°. Finally, the Bucine synthem lies unconformably over
the previuos synthems generating a fluvial terrace of the Arno River. The two lower units date back to the Early Pliocene. In fact the
Meleto clays contain mammal remains that can be found in the Triversa Faunal Unit (Early Villafranchian, late Early - Middle Pliocene)
as well as in the Ruscinian (Early Pliocene). They are also negatively magnetized and could correspond to the Gilbert Chron.
Palaeomagnetic investigations and the presence of aeolian sediments in the Montevarchi synthem and cold pollen flora allowed its
attribution to the Middle and Late Pliocene. The relationships between the different synthems and the dominant unconformities coupled
with thermochronological data recently obtained in the Apennine ridge to the east (BALESTRIERI et al., 2003) allow us to establish
that the Chianti Ridge, after a major planation, became the eastern edge of a moderate relief (Spedalino subsynthem) that was later
transformed into a wide alluvial plain (Meleto subsynthem). Updoming tilted the previous units before the modelling of a second major
unconformity that preceed the deposition of the Montevarchi synthem. It is possible that during this period the Valdarno was still connected
to the Siena Basin to the west. A third major unconformity followed finally separating the two basins. These deformations
occurred almost at sea level. During the Early and Middle Pliocene, the Apennine Ridge to the east did not exist and the Upper
Valdarno represented the western part of the peri-Adriatic Basin. The deepening of the drainage network is due to the generalised
uplift that in the nearby areas started during the Early Pleistocene. Finally the creation of the present-day Apennine watershed was not
gradual but very rapid in the geological time scale and started mostly during the Early Pleistocene
Geoarcheologia dell’insediamento musteriano di "Grotta Reali" ed evoluzione delle sorgenti del Volturno (Molise)
No full textNew sedimentoogical data from the Villafranchian deposits of Castelnuovo Garfagnana and Barga basins (Lucca, Tuscany, Italy)
No full textThe Castelnuovo Garfagnana and Barga basins are
located about 25 km north of Lucca along the
intramontane valley of the Serchio river. They are
about 5 Km wide, 15 and IO Km respectively long
and are separated by a structural high, known in
literature as "Soglia di Monte Perpoli" (Puccinelli,
1987). These basins constitute a tectonical
extensional depression, elongated in a NW-SE
direction, delimited southwest by the Alpi Apuane
and northeast by the Apennines. The geologica!
history of the Castelnuovo Garfagnana and Barga
basins, as the other depressions formed along the
Tyrrhenian margin of the Apennine chain, is related
to the Tyrrhenian rifting, active since late Tortonian,
and the counter-clockwise migration of the chainforedeep-
foreland system (Patacca et al., 1990). The
two basins, studied since 1800 for mining of lignite
and quarrying of clay, are filled with a remarkable
thickness of continental deposits, mainly of
Villafranchian age, generically interpreted in
literature as fluvio-lacustrine (Masini, 1936; Calistri,
1974). This study aims at offering a more detailed
reconstruction of the depositional history of these
deposits. A geologica! survey 1/ 10.000 scale,
together with sedimentological and compositional
analysis and paleontological data, allow to locate
five informai litostratigraphic units, whose
geometrica! relationships are shown in Fig. l. Within
each unit, a various number of lithofacies can be
seen (Miall, 1996 and, Sanchez-Moya et al., 1996
lithofacies code are used) and their association
allows to define some architectural elements (Miall,
1996). Their features and their geometrica!
relationships give rise to a more detailed and
complex reconstruction of the depositional history of
the Vi llafranchian deposits. Sixteen conglomeratic,
heterolithic, sandy and silty-clay lithofacies were
distinguished and grouped in nine architectural
elements belonging to channel belt elements and
overbank elements. The channel belt elements
consist of conglomeratic deposits (isolated channels
!C, grave! bar GB, debris flow deposit DF),
heterolithic and sandy elements (heterolithic bar HB
and sandy bar SB), while swamp (SP), pond (PO),
levee (L) and muddy-floodplain (M) constitute the
fine-grained overbank elements. On this basis four
alluvial depositional systems can be recognized. The
basai fluvial system, corresponding to
lithostratigraphic Uni t l , li es in disconformity o n the
substratum made by the metamorphic and nonmetamorphic
"Falda Toscana" units and subordinate
"Ligurian" units. !t is composed mainly of fine-
54
grained deposits, related to overbank elements with
intercalation of conglomeratic and sandy lithosomes
(Channel belt elements). Within overbank elements
SP deposits are characterized by widespread
presence of lignite (C lithofacies) and subordinate
intercalation of clays (Fm lithofacies). Tree trunks in
life-wise position have been observed. Vegetai
remains of G/yptostrobus sp., are consistent with
humid-subtropical climatic conditions. PO element is
characterized by rhythmical alternations of clay and
silt (Fh, Fsm and Fm lithofacies) containing freshwater
taxa like ostracodes (Candona spp. 1/yocypris
gibba), gastropods (Me/anoides curvicosta,
Prososthenia paulae Theodoxus sp. Laminifera
vi/lajranchiana), teeth of fish (Tinca sp., Leuciscus
cepha/us), together with charophytes oogonia and
leaves. L and M elements consist respectively of
rhythmical alternations of fine sand, silt, clay (Sh,
Fsm, Fm lithofacies) and clay and silty-clay (Fm,
Fsm lithofacies). Widespread presence of
hydromorphic paleosols (P lithofacies) containing
land taxa (e.g. Helix sp. , Pomatias e/egans, Discus
rotundatus) is observed mainly in M element.
Channel belt elements consist of isolated channels
(IC) and heterolithic bar (HB). IC element shows a
ribbon geometry and frequently "ailes d' etalement"
(sensu Friend et al. , 1979). Width-depth ratio is
consistent with stable channels. They are composed
of polygenic, grain-supported conglomerate (Gp, Gt
and Gcm lithofacies), frequently organized in fining
upward trend. HB element shows a plane-convex
upward geometry and consists of alternations
between sand and grave! (Ep, Et, St, Sp lithofacies)
organized in fining upward trend. They represent
bars migration within the channel. Compositional
data and paleocurrent analysis (northwest to
southeast direction) are consistent with a single
longitudinal (sensu Miall, 1996) fluvial course
flowing through the two basins. The whole acquired
data is consistent with the characteristic of cohesive
sediment anabranching river system, organo-clastic
sub-type (sensu Nanson & Knighton, 1996). The
second alluvial system recognized corresponds to
lithostratigraphic Uni t 2 (Fig. l). Unlike the
underlying system, Unit 2 is mainly composed of
conglomerates (channel belt elements), while finegrained
deposits (overbank elements) are
subordinate. GB and SB elements constitute channel
belt elements. GB element is made up of openwork
and matrix-filled conglomerates (Gp and Gt
lithofacies), frequently organized in fining upward
trend. Reactivation surfaces are frequently observed. SB element consists of medium to coarse-grained
sand (Sp and St lithofacies) sometimes containing
clay soft clasts. GB and SB associations are
interpreted to represent bars migration within the
channel. L and M elements constitute the overbank
elements. They are respectively characterized by fine
to medium-grained sand (Sh and Sr lithofacies) and
by drapes of clay (Fm lithofacies), while immature
paleosols (P lithofacies) are common in M element.
L and M deposits show strong affinities with the
actual overbank deposits of Serchio river. Deposits
belonging to this unit are related to a gravel bed load
braided system (sensu Sanchez-Moya et al., 1996).
Compositional and paleocurrent analysis point out
more or less the same longitudinal fluvial course,
flowing through the two basins, observed for the
underlying cohesive anabranching river system
organo-clastic sub-type. Along the Castelnuovo
Garfagnana and Barga margins, spatially limited
conglomeratic lithosome, showing latero-vertical
relationships with Unit l and 2 (Fig. l) are mapped.
Lithostratigraphic Unit 3 crops out along the
Apennine margin of the two basins. !t consists of
channel belt elements of very coarse massive
monogenic conglomerate (Gcm and Gmm
lithofacies), exclusively derived from the
surroundings "Macigno" F ormation. The same
textural characteristics were observed in the
litostratigraphic Unit 4 (Fig. l) cropping out in a
small area of the southwest margin of the Barga
basin. Besides "Macigno" clasts, the conglomerate is
also composed of deriving "Falda Toscana" and
Methamorphic units clasts. The close proximity of
source area and textural features are consistent with a
debris flow dominated fan (sensu Stanistreet & Mc
Carthy, 1993) developed transversally to the basi n' s
axis. The lithostratigraphic Unit 5 crops out in the
southwest margin of the Castelnuovo Garfagnana
basin and consists of channel belt elements.
Lithofacies Gp, Gt e Sm, (polygenic, clast supported
conglomerate and medium-coarse grained sand)
representing the composition of surrounding area are
associated in GB element. Paleocurrent analysis
shows a radiai pattem. This unit is interpreted as a
braided fluvial fan alluvial system (sensu Stanistreet
& McCarthy, 1993) developed transversally to the
basin 's axis. The whole acquired data lead to
delineate the depositional history of villafranchian
deposits cropping out in the Castelnuovo Garfagnana
and Barga basins. The results of this study can be
summarized in two principal points: i) onset, in a
humid sub-tropical climate phase, of a first alluvial
system, flowing through the two basins and related
to a cohesive sediment anabranching river (sub-type
organo-clastic) characterized by a prevalent finegrained
overbank organic-rich sedimentation. At the
same time coalescent debris flow dominated fan,
mainly derived from Apennines margin, forms
transversally to the basins axis. ii) Development of a
gravel bed load braided alluvial system,
characterized by prevalent gravelly channel belt
deposits, flowing through the two basins. The
erosive contact between this system and the
underlying one, is an abrupt facies change inferring a
possible disconformity surface. At the same time
debris flow dominated fans derived from the
Apennines margin continue to develop. Although the
proposed reconstruction involves the necessity of a
disconformity surface also within these deposits, the
spatially limited outcrops and the frequently
weathering do not permit to evaluate this hypothesis.
During this depositional phase a braided fluvial fan
derived from the Apuan Alps develops transversally
in the Castelnuovo Garfagnana basin. This
palaeoenvironment reconstruction implies that
Monte Perpoli high plays a different role compared
to that proposed by other authors. In our
interpretation, according to the sedimentological and
statistica! compositional data (Sodini M. et al.,
2002), this area acted as a sedimentary by-pass since
the opening (Lower Villafranchian) of the
Castelnuovo Garfagnana and Barga basins. This
interpretation is consistent with most recent data
about Alpi Ar uane uplift times (Molli G., 2001)
Authors' Reply: "On the Importance of Considering Glycosylation when Evaluating Biologic Therapies"
No full textStaff experiences of providing support to students who are managing mental health challenges: A qualitative study from two Australian universities (vol 12, pg 192, 2014)
No full textMargaret McAllister, Dianne Wynaden, Brenda Happell, Trudi Flynn, Victoria Walters, Ravani
Duggan, Louise Byrne, Karen Heslop & Cadeyrn Gaskin (2014) Staff experiences of providing
support to students who are managing mental health challenges: A qualitative study from two
Australian universities. Advances in Mental Health: Promotion, Prevention and Early Intervention,
12(3), pp. 192-201. http://dx.doi.org/10.1080/18374905.2014.11081897
When the above article was first published, Victoria Walters’, Ravani Duggan’s and Karen
Heslop’s names were spelled incorrectly. This has now been corrected online
Niosomi contenenti molecole biotecnologiche ad attivita’ antierpetica somministrati per via nasale
No full textClinical Diagnosis of Atheroembolic Renal Disease: Challenging but not necessarily a “Needle in a Haystack”
No full text
Negative correlation between flow-mediated dilation (FMD) and arterial size: true association or mathematical artefact?
No full textObjective: FMD is a marker of endothelial function often used as a surrogate endpoint in lipid lowering clinical trials. It is computed as the ratio of the brachial artery absolute diameter change (ADC), over the baseline diameter (BD). The rationale for this formula is the assumption of a proportionality between ADC and BD. A negative correlation between FMD and BD has been systematically reported in many contexts and explained with a variety of biological reasons. Besides this, the explanation may be purely mathematical, because BD is the denominator of the FMD formula. Aim of the present study was to assess the influence of mathematical artefacts on this correlation.
Methods: we measured FMD on 119 dyslipidemic patients and we computed the correlation coefficient (R) between FMD and BD and between ADC and BD. We also run 1000 computer-simulations of the same correlations in virtual patients having, in place of BD and ADC, two variables totally random and uncorrelated, produced by a random number generator. The correlations obtained in the real and simulated contexts were then compared.
Results: Similarly to what reported in the literature, in the real data the R between FMD and BD was -0.28 (95% C.I. -0.44 to -0.11) but the assumed proportionality between ADC and BD was not confirmed (r=-0.13, 95% C.I. -0.31 to 0.05). Using simulated data the R between FMD and BD was -0.27 (95%C.I. -0.39 to -0.12).
Conclusions: The lack of proportionality between ADC and BD as well as the almost identical correlation coefficients obtained using the real and the simulated variables suggest that the association between FMD and BD is mostly attributable to mathematical artefacts
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