796 research outputs found
A website to explore the TINITALY/01 DEM
In 2007, a new digital elevation model (DEM) of the whole Italian territory, named TINITALY/01, was presented by Tarquini et al. [2007]. This DEM was the final result of the DIGITALIA project supported by the Italian Ministero dell’Ambiente e della Tutela del Territorio in the framework of a general agreement involving the Istituto Nazionale di Geofisica e Vulcanologia (INGV). The whole database of this DEM, in the form of a 10 m cell size grid, is available to the INGV research community at the web portal Kharita (http://kharita.rm.ingv.it/dmap/). Tarquini et al. [2007] mentioned in short a dedicated website (http://webgis.pi.ingv.it/), where authorized users were allowed to explore full resolution nadiral or perspective shaded relief images (in stereo or conventional format) obtained from the TINITALY/01 DEM. The navigation of this website is now opened to the public. The present technical report illustrates this website, describing its content and unfolding related technological aspects
Multiview 3D reconstruction in geosciences
Multiview three-dimensional (3D) reconstruction is a technology that allows the creation of 3D models of a given scenario from a series of overlapping pictures taken using consumer-grade digital cameras. This type of 3D reconstruction is facilitated by freely available software, which does not require expert-level skills. This technology provides a 3D working environment, which integrates sample/field data visualization and measurement tools. In this study, we test the potential of this method for 3D reconstruction of decimeter-scale objects of geological interest. We generated 3D models of three different outcrops exposed in a marble quarry and two solids: a volcanic bomb and a stalagmite. Comparison of the models obtained in this study using the presented method with those obtained using a precise laser scanner shows that multiview 3D reconstruction yields models that present a root mean square error/average linear dimensions between 0.11 and 0.68%. Thus this technology turns out to be an extremely promising tool, which can be fruitfully applied in geosciences
Release of a 10-m-resolution DEM for the Italian territory: Comparison with global-coverage DEMs and anaglyph-mode exploration via the web
The 10-m-resolution TINITALY/01 DEM (Tarquini et al., 2007) is compared with the two, coarser-resolution, global-coverage, spaceborne-based SRTM and ASTER DEMs and with a high-resolution, LIDAR-derived DEM. Afterwards, we presented a webGIS which allows to explore a 10-m-resolution anaglyph layer showing the landforms of the whole Italian territory in 3D. The webGIS (http://tinitaly.pi.ingv.it/) is open to the public, and can be used to carry out a preliminary analysis of landforms. The TINITALY/01 DEM is available for scientific purposes on the basis of a research agreement (see the above website or write to [email protected])
Long-term effects of bariatric surgery on meal disposal and beta-cell function in diabetic and nondiabetic patients.
Gastric bypass surgery leads to marked improvements in glucose tolerance and insulin sensitivity in obese type 2 diabetes; the impact on glucose fluxes in response to a physiological stimulus - such as a mixed meal (MTT) - has not been determined. We administered an MTT to 12 obese type 2 diabetic patients (T2D) and 15 obese nondiabetic subjects (ND) before and one year after surgery (10 T2D and 11 ND) using the double-tracer technique and modeling of ß-cell function. In both groups postsurgery, tracer-derived appearance of oral glucose was biphasic, a rapid increase followed by a sharp drop, a pattern that was mirrored by postprandial glucose levels and insulin secretion. In diabetic patients, surgery lowered fasting and postprandial glucose levels; peripheral insulin sensitivity increased in proportion to weight loss (∼30%), ß-cell glucose sensitivity doubled but did not normalize (viz. 21 nonsurgical obese and lean controls). Endogenous glucose production, however, was less suppressed during the MMT as the combined result of a relative hyperglucagonemia and the rapid fall in plasma glucose and insulin levels.We conclude that, in type 2 diabetes bypass surgery changes the postprandial response to a dumping-like pattern, improves glucose tolerance, ß-cell function, and peripheral insulin sensitivity but worsens endogenous glucose output in response to a physiological stimulus
Mode of onset of type 2 diabetes from normal or impaired glucose tolerance
Wartości stężenia glukozy na czczo (FPG, fasting plasma
glucose) wskazują, jakie jest ryzyko wystąpienia
cukrzycy typu 2. Nie wiadomo, czy hiperglikemia
rozwija się stopniowo, czy też narasta skokowo.
W grupie mężczyzn i nieciężarnych kobiet
w wieku 35–64 lat, biorących udział w badaniu populacyjnym
Mexico City Diabetes Study, podczas doustnego
testu tolerancji glukozy (OGTT, oral glucose
tolerace test) sprawdzano stężenie glukozy i insuliny
w surowicy. Testy te przeprowadzono w czasie
badania wstępnego (n = 2279) oraz po 3,25 (n = 1740) i 7 latach (n = 1711) obserwacji.
Wśród osób z prawidłową tolerancją glukozy (NGT,
normal glucose tolerance) w czasie wszystkich trzech
badań (osoby niechorujące, n = 911) wartość FPG
wzrosła nieznacznie (0,23 ± 0,79 mmol/l, średnia ± SD;
p < 0,0001) w okresie 7 lat. Natomiast wystąpienie
cukrzycy wśród osób z NGT (n = 98) poprzedzał znaczny wzrost FPG, niezależnie od czasu zachorowania
(3,06 ± 2,57 i 2,94 ± 3,11 mmol/l, odpowiednio
w 3,25. i 7. roku obserwacji; p < 0,0001 vs. osoby
niechorujące). Podobnie u osób z upośledzoną
tolerancją glukozy, które zachorowały na cukrzycę
(n = 75), wartość FPG wzrosła o 3,14 ± 3,83 i 3,12 ± 3,61 mmol/l (p < 0,0001 vs. osoby niechorujące).
U 3/4 osób, które zachorowały na cukrzycę, obserwowano
wzrost FPG powyżej 90. percentyla rozkładu
wzrostu glikemii u osób niechorujących na cukrzycę.
U osób, które zachorowały na cukrzycę,
stwierdzono wyższe wyjściowe wartości wskaźnika
masy ciała (BMI, body mass index) (30,4 ± 4,9 vs.
27,3 ± 4,0 kg/m2; p < 0,001) i insulinemii na czczo
(120 ± 78 vs. 84 ± 84 pmol/l; p < 0,02) niż u osób
niechorujących, mimo że nie zaobserwowano zmian
żadnego z tych parametrów przed zachorowaniem.
Przeciwnie, zmiany stężenia insuliny, w stosunku do
wcześniejszych oznaczeń, w 2. godzinie testu tolerancji
glukozy wykazywały istotną statystycznie odwrotną
zależność (p < 0,0001) z odpowiadającymi
zmianami w FPG. W czasie 3-letniej obserwacji
stwierdzono, iż początek cukrzycy charakteryzuje się
częściej skokowym niż stopniowym wzrostem glikemii,
co można w pewnym stopniu wyjaśnić zmniejszeniem
uwalniania insuliny w odpowiedzi na stymulację
glukozą.Fasting plasma glucose concentrations (FPG) predict
development of type 2 diabetes. Whether hyperglycemia
evolves from normoglycemia gradually over
time or as a step increase is not known. We measured
plasma glucose and insulin levels during oral
glucose testing in 35-to 64-year-old men and nonpregnant
women from a population-based survey
(Mexico City Diabetes Study) at baseline (n = 2,279)
and after 3.25 (n = 1,740) and 7 years (n = 1,711) of
follow-up. In subjects with normal glucose tolerance
(NGT) on all three occasions (nonconverters; n = 911),
FPG increased only slightly (0.23 ± 0.79 mmol/l, mean ±
± SD; P < 0.0001) over 7 years. In contrast, conversion
to diabetes among NGT subjects (n = 98) was
marked by a large step-up in FPG regardless of time
of conversion (3.06 ± 2.57 and 2.94 ± 3.11 mmol/l,
respectively, at 3.25 and 7 years; P < 0.0001 vs. nonconverters).
Likewise, in subjects who converted to
diabetes from impaired glucose tolerance (n = 75),
FPG rose by 3.14 ± 3.83 and 3.12 ± 3.61 mmol/l
(P < 0.0001 vs. nonconverters). Three-quarters of
converters had increments in FPG above the 90th
percentile of the corresponding increments in nonconverters.
Converters had higher baseline BMI (30.4 ±
± 4.9 vs. 27.3 ± 4.0 kg/m2; P < 0.001) and fasting
plasma insulin values (120 ± 78 vs. 84 ± 84 pmol/l;
P < 0.02) than nonconverters; however, no consistent
change in either parameter had occurred before
conversion. In contrast, changes in 2-h postglucose
insulin levels between time of conversion
and preceding measurement were significantly (P <
< 0.0001) related to the corresponding changes in
FPG in an inverse manner. We conclude that, within
a 3-year time frame, the onset of diabetes is very often
rapid rather than gradual and is in part explained by
a fall in glucose-stimulated insulin response
- …