448 research outputs found
Pengaruh Penggunaan Lingkungan Sekitar Sekolah Sebagai Media Pembelajaran Terhadap Hasil Belajar Siswa di SMPK St. Gabriel Ndona
Penelitian ini bertujuan untuk mengetahui pengaruh penggunaan lingkungan sekitar sekolah sebagai media pembelajaran pada materi klasifikasi makhluk hidup terhadap hasil belajar siswa kelas VII SMPK ST. Gabriel Ndona. Jenis penelitian ini adalah penelitian eksperimen dengan pendekatan kuantitatif. Desain penelitian one grup eksperimen desain (one group, pretest post-test). Populasi penelitian ini yaitu seluruh siswa kelas VII SMPK St. Gabriel Ndona yang berjumlah 29 orang dan sekaligus dijadikan sebagai sampel, cara yang diperoleh dengan teknik purposive sampling. Data yang diperoleh dianalisis statistik deskriptif. Analisis data menunjukan bahwa adanya pengaruh penggunaan lingkungan sekolah sebagai media pembelajaran terhadap hasil belajar siswa pada materi klasifikasi makhluk hidup kelas VII SMPK ST. Gabriel Ndona. Hal ini dibuktikan dengan rata-rata hasil belajar aspek kognitif sebesar 85,52, untuk hasil belajar aspek afektif siswa sebesar 87,66 dan hasil belajar aspek psikomotorik siswa yaitu sebesar 88,14. Berdasarkan hasil analisis uji t (paired sampel t-test), maka dapat diperoleh hasil bahwa Sig. (2 tailed)= 0,000 < 0,05, maka H0 ditolak dan H1 diterima
Use of remote digital surveys to generate exposure models of residential structures in Chile
This article describes a methodology used to build detailed exposure models of residential structures in three cities of Chile
using remote digital surveys. The models provide the location of the structures classified into 18 different structural
typologies. Two tools were used simultaneously to build the models: Google StreetView, and GEM’s Inventory Data
Capture Tool. The method is described, a summary of the results of the exposure models is presented, and the detailed
results of the local models are compared with a previously developed national exposure model for the whole country. The
proposed methodology to develop exposure models proved to be useful, simple, and low cost, and can be replicated
elsewhere with proper StreetView coverage. The methodology is accurate to count structures, despite presenting certain
difficulties to classify the surveyed buildings into different structural typologies. The developed exposure models represent
an important input for risk calculations, thus improving technical capabilities for seismic risk management of the country
Nanostructure of cellulose microfibrils in spruce wood
The structure of cellulose microfibrils in wood is not known in detail, despite the abundance of cellulose in woody biomass and its importance for biology, energy, and engineering. The structure of the microfibrils of spruce wood cellulose was investigated using a range of spectroscopic methods coupled to small-angle neutron and wide-angle X-ray scattering. The scattering data were consistent with 24-chain microfibrils and favored a “rectangular” model with both hydrophobic and hydrophilic surfaces exposed. Disorder in chain packing and hydrogen bonding was shown to increase outwards from the microfibril center. The extent of disorder blurred the distinction between the I alpha and I beta allomorphs. Chains at the surface were distinct in conformation, with high levels of conformational disorder at C-6, less intramolecular hydrogen bonding and more outward-directed hydrogen bonding. Axial disorder could be explained in terms of twisting of the microfibrils, with implications for their biosynthesis
Type I tympanoplasty meta-analysis : a single variable analysis
OBJECTIVE : To determine which independent variables influencing the efficacy of type I tympanoplasty in adult and pediatric populations.
DATA SOURCES : A search of the PubMed database and Cochrane Database of Systematic Reviews using the key words "tympanoplasty OR myringoplasty" from January 1966 to July 2014 was performed.
STUDY COLLECTION : Studies reporting outcomes of myringoplasty or Type I tympanoplasty in primary non-cholesteatomatous chronic tympanic membrane (TM) perforation were included.
DATA EXTRACTION : Of 4,698 abstracts reviewed, 214 studies involving 26,097 patients met our inclusion criteria and contributed to meta-analysis.
DATA SYBTHESIS : The primary outcome of success was defined as closure rate at 12 months. The independent variables analyzed were age, follow-up period, approach, graft material, perforation cause, size, location, ear dryness, and surgical technique. Only those studies providing data on a given parameter of interest could be included when comparing each variable.
CONCLUSION : The weighted average success rate of tympanic closure was 86.6%. Based on this meta-analysis, pediatric surgery has a 5.8% higher failure rate than adults and there is no correlation between follow-up period and success. Other variables associated with improved closure rates include perforation with a size less than 50% of total area (improved by 6.1%) and the use of cartilage as a graft (improved by 2.8% compared with fascia), while ears that were operated on while still discharging, those in different locations of the pars tensa, or using different surgical approaches or techniques did not have significantly different outcomes.http://journals.lww.com/otology-neurotology2017-06-30hb2016Speech-Language Pathology and Audiolog
Density-dependence of functional development in spiking cortical networks grown in vitro
During development, the mammalian brain differentiates into specialized
regions with distinct functional abilities. While many factors contribute to
functional specialization, we explore the effect of neuronal density on the
development of neuronal interactions in vitro. Two types of cortical networks,
dense and sparse, with 50,000 and 12,000 total cells respectively, are studied.
Activation graphs that represent pairwise neuronal interactions are constructed
using a competitive first response model. These graphs reveal that, during
development in vitro, dense networks form activation connections earlier than
sparse networks. Link entropy analysis of dense net- work activation graphs
suggests that the majority of connections between electrodes are reciprocal in
nature. Information theoretic measures reveal that early functional information
interactions (among 3 cells) are synergetic in both dense and sparse networks.
However, during later stages of development, previously synergetic
relationships become primarily redundant in dense, but not in sparse networks.
Large link entropy values in the activation graph are related to the domination
of redundant ensembles in late stages of development in dense networks. Results
demonstrate differences between dense and sparse networks in terms of
informational groups, pairwise relationships, and activation graphs. These
differences suggest that variations in cell density may result in different
functional specialization of nervous system tissue in vivo.Comment: 10 pages, 7 figure
The Deformation of Expanded Clay Syntactic Foams during Compression Characterized by Acoustic Emission
The deformation and failure mechanisms in syntactic foams with different metal matrices were investigated in this study. The syntactic foams were produced by the infiltration method using lightweight expanded clay particles (LECA) as a space holder and commercially pure Al or eutectic Al-12%Si alloy for the matrices. The samples were compressed at room temperature; simultaneously, the acoustic emission (AE) response and the surface deformation were monitored and collated with the deformation curves. In the case of the Al foam, ductile behavior with long plateau stress was observed. During this plateau regime, multiple active shear bands were detected. In contrast, the AlSi12 foam exhibited more brittle deformation behavior. At the end of the quasi-linear stage, the localization of the strain started within one large shear band, accompanied by a significant stress drop. The AE analysis revealed that the deformation was mostly governed by the fracture of LECA particles and the plastic deformation of the matrix material for both types of foams. After strain localization, in the case of the AlSi12 foam, the fracture of the matrix became significant, causing the deterioration of the sample. As for the Al foam, besides the fracture of the LECA particles, the plastic deformation of the matrix played an important role in preventing the foam from falling apart
Non-reciprocal interactions between K+ and Na+ ions in barley (Hordeum vulgare L.)
The interaction of sodium and potassium ions in the context of the primary entry of Na+ into plant cells, and the subsequent development of sodium toxicity, has been the subject of much recent attention. In the present study, the technique of compartmental analysis with the radiotracers 42K+ and 24Na+ was applied in intact seedlings of barley (Hordeum vulgare L.) to test the hypothesis that elevated levels of K+ in the growth medium will reduce both rapid, futile Na+ cycling at the plasma membrane, and Na+ build-up in the cytosol of root cells, under saline conditions (100 mM NaCl). We reject this hypothesis, showing that, over a wide (400-fold) range of K+ supply, K+ neither reduces the primary fluxes of Na+ at the root plasma membrane nor suppresses Na+ accumulation in the cytosol. By contrast, 100 mM NaCl suppressed the cytosolic K+ pool by 47–73%, and also substantially decreased low-affinity K+ transport across the plasma membrane. We confirm that the cytosolic [K+]:[Na+] ratio is a poor predictor of growth performance under saline conditions, while a good correlation is seen between growth and the tissue ratios of the two ions. The data provide insight into the mechanisms that mediate the toxic influx of sodium across the root plasma membrane under salinity stress, demonstrating that, in the glycophyte barley, K+ and Na+ are unlikely to share a common low-affinity pathway for entry into the plant cell
A pharmacological analysis of high-affinity sodium transport in barley (Hordeum vulgare L.): a 24Na+/42K+ study
Soil sodium, while toxic to most plants at high concentrations, can be beneficial at low concentrations, particularly when potassium is limiting. However, little is known about Na+ uptake in this ‘high-affinity’ range. New information is provided here with an insight into the transport characteristics, mechanism, and ecological significance of this phenomenon. High-affinity Na+ and K+ fluxes were investigated using the short-lived radiotracers 24Na and 42K, under an extensive range of measuring conditions (variations in external sodium, and in nutritional and pharmacological agents). This work was supported by electrophysiological, compartmental, and growth analyses. Na+ uptake was extremely sensitive to all treatments, displaying properties of high-affinity K+ transporters, K+ channels, animal Na+ channels, and non-selective cation channels. K+, NH4+NH4+, and Ca2+ suppressed Na+ transport biphasically, yielding IC50 values of 30, 10, and <5 μM, respectively. Reciprocal experiments showed that K+ influx is neither inhibited nor stimulated by Na+. Sodium efflux constituted 65% of influx, indicating a futile cycle. The thermodynamic feasibility of passive channel mediation is supported by compartmentation and electrophysiological data. Our study complements recent advances in the molecular biology of high-affinity Na+ transport by uncovering new physiological foundations for this transport phenomenon, while questioning its ecological relevance
Genome-wide transcriptional analysis of salinity stressed japonica and indica rice genotypes during panicle initiation stage
Rice yield is most sensitive to salinity stress imposed during the panicle initiation (PI) stage. In this study, we have focused on physiological and transcriptional responses of four rice genotypes exposed to salinity stress during PI. The genotypes selected included a pair of indicas (IR63731 and IR29) and a pair of japonica (Agami and M103) rice subspecies with contrasting salt tolerance. Physiological characterization showed that tolerant genotypes maintained a much lower shoot Na(+) concentration relative to sensitive genotypes under salinity stress. Global gene expression analysis revealed a strikingly large number of genes which are induced by salinity stress in sensitive genotypes, IR29 and M103 relative to tolerant lines. We found 19 probe sets to be commonly induced in all four genotypes. We found several salinity modulated, ion homeostasis related genes from our analysis. We also studied the expression of SKC1, a cation transporter reported by others as a major source of variation in salt tolerance in rice. The transcript abundance of SKC1 did not change in response to salinity stress at PI stage in the shoot tissue of all four genotypes. However, we found the transcript abundance of SKC1 to be significantly higher in tolerant japonica Agami relative to sensitive japonica M103 under control and stressed conditions during PI stage. ELECTRONIC SUPPLEMENTARY MATERIAL: Supplementary material is available in the online version of this article at http://dx.doi.org/10.1007/s11103-006-9112-0 and is accessible for authorized users
HCN emission from translucent gas and UV-illuminated cloud edges revealed by wide-field IRAM 30m maps of Orion B GMC: Revisiting its role as tracer of the dense gas reservoir for star formation
We present 5 deg^2 (~250 pc^2) HCN, HNC, HCO+, and CO J=1-0 maps of the Orion
B GMC, complemented with existing wide-field [CI] 492 GHz maps, as well as new
pointed observations of rotationally excited HCN, HNC, H13CN, and HN13C lines.
We detect anomalous HCN J=1-0 hyperfine structure line emission almost
everywhere in the cloud. About 70% of the total HCN J=1-0 luminosity arises
from gas at A_V < 8 mag. The HCN/CO J=1-0 line intensity ratio shows a bimodal
behavior with an inflection point at A_V < 3 mag typical of translucent gas and
UV-illuminated cloud edges. We find that most of the HCN J=1-0 emission arises
from extended gas with n(H2) < 10^4 cm^-3, even lower density gas if the
ionization fraction is > 10^-5 and electron excitation dominates. This result
explains the low-A_V branch of the HCN/CO J=1-0 intensity ratio distribution.
Indeed, the highest HCN/CO ratios (~0.1) at A_V < 3 mag correspond to regions
of high [CI] 492 GHz/CO J=1-0 intensity ratios (>1) characteristic of
low-density PDRs. Enhanced FUV radiation favors the formation and excitation of
HCN on large scales, not only in dense star-forming clumps. The low surface
brightness HCN and HCO+ J=1-0 emission scale with I_FIR (a proxy of the stellar
FUV radiation field) in a similar way. Together with CO J=1-0, these lines
respond to increasing I_FIR up to G0~20. On the other hand, the bright HCN
J=1-0 emission from dense gas in star-forming clumps weakly responds to I_FIR
once the FUV radiation field becomes too intense (G0>1500). The different power
law scalings (produced by different chemistries, densities, and line excitation
regimes) in a single but spatially resolved GMC resemble the variety of
Kennicutt-Schmidt law indexes found in galaxy averages. As a corollary for
extragalactic studies, we conclude that high HCN/CO J=1-0 line intensity ratios
do not always imply the presence of dense gas.Comment: accepted for publication in A&A. 24 pages, 18 figures, plus Appendix.
Abridged Abstract. English language not edite
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