714 research outputs found

    Calculation of Land Water Balance and Its Utilization for Determining the Growing Season in the Pulau-Pulau Aru District, Aru Islands Regency, Maluku Province

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    There are various methods that can be used to determine the growing season in an area; one of them is through the calculation of the land water balance. This study aimed to determine the presence of groundwater and determine the planting season in the Pulau-Pulau Aru Sub-District. In this study, the calculation of the regional average rainfall used monthly time series rainfall data for 30 years of observation (1991–2020). The calculation of land water balance used the ThornthwaiteMather method, and the determination of the growing season based on the values of soil water content at optimum conditions and the ratio between rainfalls and potential evapotranspiration. The results showed that the optimum soil water content for plants under conditions of 75% chance of rainfall lasted for 7 months (December to June), which was 2 months shorter than normal. The length of growing season with a 75% chance of rainfall lasted for 7 months (December to June), 2 months shorter than the growing season under normal rainfall conditions

    Strain rate sensitivity of mechanical properties of the ZK60 alloy with the high degree of corrosion damage

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    There is a strong belief that hydrogen absorbed by magnesium alloys during corrosion can cause their stress corrosion cracking. One of the characteristic markers indicating the involvement of diffusible hydrogen into the fracture mechanism of metals is the negative strain rate dependence of the embrittlement degree. Recent studies show that the loss of ductility of the ZK60 alloy specimens subjected to a short-term (1.5 h) pre-exposure in a corrosive medium actually decreases with the increasing strain rate. However, after the removal of corrosion products from the surface of the specimens, the strain rate dependence of the ductility loss becomes positive, which indicates the absence of hydrogen in the bulk of the metal. At short-term exposure in a corrosive environment, the deep penetration of hydrogen into a metal could be limited due to the insufficient time for hydrogen diffusion. The paper studies the mechanical behavior of the ZK60 alloy subjected to a longer (12 h) pre-exposure in a corrosive medium followed by tensile testing in air at various strain rates. The authors consider the effect of strain rate, long-term pre-exposure in a corrosive medium, and subsequent removal of corrosion products on the strength, ductility, stages of work hardening, and localized deformation, as well as on the state of the side and fracture surfaces of specimens. It is established that the ductility loss of the specimens pre-exposed in a corrosive medium for 12 h decreases with the increasing strain rate, regardless of whether the corrosion products have been removed from their surface or not. It is shown that in this case, the negative strain rate dependence of the ductility loss is associated not with hydrogen dissolved in the bulk of a metal but with the presence of severe corrosion damage of the specimens’ surface. An explanation for the effect of corrosion damage on the mechanical properties and their strain rate sensitivity is proposed

    The effect of strain rate on mechanical properties and fracture mode of the AZ31 alloy and commercially pure magnesium pre-exposed in a corrosive medium

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    Magnesium alloys are promising materials for aviation, automotive engineering, and medicine, however, due to the low resistance to stress corrosion cracking (SCC), their wide application is limited. To create alloys with high resistance to SCC, a comprehensive study of this phenomenon nature is required. Previously, it was suggested that diffusible hydrogen and corrosion products formed on the magnesium surface can play an important role in the SCC mechanism. However, the contribution of each of these factors to the SCC-induced embrittlement of magnesium and its alloys is understudied. Since the influence of diffusible hydrogen on the mechanical properties of metals increases with the strain rate decrease, the study of the strain rate sensitivity of the SCC-susceptibility of magnesium alloys is a critical task. In this work, the authors studied the effect of the strain rate in the range from 5•10−6 to 5•10−4 s−1 on the mechanical properties, the state of the side and fracture surfaces of the as-cast commercially pure magnesium and the AZ31 alloy before and after exposure to a corrosive environment and after removal of corrosion products. The study identified that the preliminary exposure to a corrosive medium leads to the AZ31 alloy embrittlement, but does not affect the mechanical properties and the fracture mode of pure magnesium. The authors found that the AZ31 alloy embrittlement caused by the preliminary exposure to a corrosive medium appears extensively only at the low strain rate and only if the layer of corrosion products is present on the specimens’ surface. The study shows that a change in the strain rate has little effect on the mechanical properties of pure magnesium. The authors concluded that the main cause of the AZ31 alloy embrittlement after soaking in a corrosive medium is the corrosion products layer, which presumably contains the embrittling agents such as hydrogen and residual corrosive medium

    The dependence of the biodegradable ZX10 alloy corrosion process on the structural factors and local pH level

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    Magnesium biodegradable alloys are a promising material for self-dissolving surgical implants. Magnesium is known to be sensitive to electrochemical corrosion due to the galvanic effect between the matrix and particles of secondary phases and inclusions. Another important factor is the pH level. The behavior of certain chemical reactions depends on the pH level, so one can assume that the pH level of a corrosive medium at the material surface is a factor determining what chemical reactions can occur there. Finally, there is evidence that variability of the crystallographic orientation of the grains may be a cause of anisotropy of corrosion properties. The purpose of this work is to reveal the influence of the electrode potential of the microstructural elements, the crystallographic orientation of the grains, and the pH level of the near-surface volume of the corrosion solution on the corrosion process. In the study, sections of 2×1.5 mm were marked on the ZX10 alloy samples, for which maps of the distribution of crystallographic orientations and chemical composition were drawn. To assess the influence of the electrode potential of the particles, the authors carried out a Kelvin probe mapping in the 90×90 µm area. Next, corrosion tests were carried out with video filming of the surface on the marked area. To determine the pH level influence, the solution circulation in the cell was varied. Upon completion of the tests, corrosion products and corrosion damage were examined in detail. According to the results, the pH level in the liquid near-surface micro-volumes has a greater influence than the electrode potential of the particles as it provokes the formation of corrosion products of a different composition, which leads to passivation of the surface areas around the particles. The authors identified two different types of filiform corrosion. For filiform corrosion, a correlation between the corrosion direction and the crystallographic orientation of the grains was established

    Measuring galaxy environment with the synergy of future photometric and spectroscopic surveys

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    We exploit the synergy between low-resolution spectroscopy and photometric redshifts to study environmental effects on galaxy evolution in slitless spectroscopic surveys from space. As a test case, we consider the future Euclid Deep survey (∼40 deg2), which combines a slitless spectroscopic survey limited at Hα flux ≥5 × 10−17 erg cm−2 s−1 and a photometric survey limited in H band (H ≤ 26). We use Euclid-like galaxy mock catalogues, in which we anchor the photometric redshifts to the 3D galaxy distribution of the available spectroscopic redshifts. We then estimate the local density contrast by counting objects in cylindrical cells with radius from 1 to 10 h−1Mpc, over the redshift range 0.9 < z < 1.8. We compare this density field with the one computed in a mock catalogue with the same depth as the Euclid Deep survey (H = 26) but without redshift measurement errors. We find that our method successfully separates high- from low-density environments (the last from the first quintile of the density distribution), with higher efficiency at low redshift and large cells: the fraction of low-density regions mistaken by high-density peaks is <1 per cent for all scales and redshifts explored, but for scales of 1 h−1Mpc for which is a few per cent. These results show that we can efficiently study environment in photometric samples if spectroscopic information is available for a smaller sample of objects that sparsely samples the same volume. We demonstrate that these studies are possible in the Euclid Deep survey, i.e. in a redshift range in which environmental effects are different from those observed in the local Universe, hence providing new constraints for galaxy evolution models

    Empirical Modeling of the Redshift Evolution of the [N II]/Hα Ratio for Galaxy Redshift Surveys

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    We present an empirical parameterization of the [N ii]/Hα flux ratio as a function of stellar mass and redshift valid at 0 43.0 for galaxies at redshifts z ~ 1.5. This has implications for the prediction of Hα emitters for Euclid and WFIRST. We also study the impact of blended Hα and [N ii] on the accuracy of measured spectroscopic redshifts

    Using bottleneck adapters to identify cancer in clinical notes under low-resource constraints

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    Processing information locked within clinical health records is a challenging task that remains an active area of research in biomedical NLP. In this work, we evaluate a broad set of machine learning techniques ranging from simple RNNs to specialised transformers such as BioBERT on a dataset containing clinical notes along with a set of annotations indicating whether a sample is cancer-related or not. Furthermore, we specifically employ efficient fine-tuning methods from NLP, namely, bottleneck adapters and prompt tuning, to adapt the models to our specialised task. Our evaluations suggest that fine-tuning a frozen BERT model pre-trained on natural language and with bottleneck adapters outperforms all other strategies, including full fine-tuning of the specialised BioBERT model. Based on our findings, we suggest that using bottleneck adapters in low-resource situations with limited access to labelled data or processing capacity could be a viable strategy in biomedical text mining

    Faktor-Faktor Yang Mempengaruhi Mahasiswa Tingkat III Semester V Dalam Menyelesaikan Target Pasien Komprehensif Di Klinik Pendidikan Jurusan Kesehatan Gigi Kupang

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    Pelayanan asuhan kesehatan gigi dan mulut diberikan kepada masyarakat yang bersifat komprehensif berupa kegiatan promotif, tindakan preventif dan kuratif sederhana, menyelesaikan hygiene pemeliharaan alat-alat kedokteran gigi dan lingkungan kerja. Untuk mengetahui faktor-faktor yang mempengaruhi mahasiswa tingkat III semester V dalam menyelesaikan target pasien komprehensif di klinik pendidikan jurusan kesehatan gigi kupang. Jenis penelitian ini menggunakan penelitian deskriptif yaitu penelitian yang dilakukan dengan tujuan untuk mendapatkan gambaran tentang jumlah mahasiswa yang mengerjakan pasien komprehensif di Klinik Pendidikan Jurusan Kesehatan Gigi Kupang. Motivasi mahasiswa dalam menyelesaikan target pasien komprehensif gigi dan mulut termasuk kategori baik (68,3%), pengetahuan mahasiswa dalam pelayanan asuhan keperawatan gigi dan mulut termasuk kategori kurang (40,5%), tingkat kooperatif pasien dalam pelayanan asuhan kesehatan gigi dan mulut termasuk kategori baik (68,3%). Motivasi mahasiswa dalam menyelesaikan target pasien komprehensif termasuk kategori baik (68,3%) karena mahasiswa berada pada usia kematangan dimana mahasiswa harus berusaha dalam menyelesaiakan target praktikum yang sedang dihadapi. Saran : Meningkatkan kemampuan dan keterampilan peserta didik dengan lebih memperbanyak praktikum serta meningkatkan mutu pelayanan di klinik

    The transcriptional coactivator Querkopf controls adult neurogenesis

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    The adult mammalian brain maintains populations of neural stem cells within discrete proliferative zones. Understanding of the molecular mechanisms regulating adult neural stem cell function is limited. Here, we show that MYST family histone acetyltransferase Querkopf (Qkf, Myst4, Morf)-deficient mice have cumulative defects in adult neurogenesis in vivo, resulting in declining numbers of olfactory bulb interneurons, a population of neurons produced in large numbers during adulthood. Qkf-deficient mice have fewer neural stem cells and fewer migrating neuroblasts in the rostral migratory stream. Qkf gene expression is strong in the neurogenic subventricular zone. A population enriched in multipotent cells can be isolated from this region on the basis of Qkf gene expression. Neural stem cells/progenitor cells isolated from Qkf mutant mice exhibited a reduced self-renewal capacity and a reduced ability to produce differentiated neurons. Together, our data show that Qkf is essential for normal adult neurogenesis
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