1,573 research outputs found
A Socio-Informatic Approach to Automated Account Classification on Social Media
Automated accounts on social media have become increasingly problematic. We
propose a key feature in combination with existing methods to improve machine
learning algorithms for bot detection. We successfully improve classification
performance through including the proposed feature.Comment: International Conference on Social Media and Societ
Efektivitas Sari Buah Belimbing Wuluh (Averrhoa Bilimbil) sebagai Larvasida Alami terhadap Nyamuk Aedessp
Latar Belakang: Belimbing wuluh (Averrhoa bilimbiL.) merupakan salah satu tanaman yang dimanfaatkan sehari-hari sebagai bumbu masakan. Buah belimbing wuluh (Averrhoa bilimbiL.) merupakan tanaman yang berpotensi sebagai larvasida, kandungan belimbing wuluh (Averrhoa bilimbiL.) yang dapat berfungsi sebagai larvasida yaitu alkaloid, saponin, dan flavonoid.
Tujuan: Penelitian ini bertujuan untuk mengetahui efektifitas buah belimbing wuluh (Averrhoa bilimbi L.) sebagai larvasida nyamuk Aedes sp.
Metode: Penelitian ini bersifat Experimental laboratories dengan rancangan post test only control group, subjek dibagi dalam dua kelompok yaitu kelompok perlakuan dan kelompok kontrol. Sampel penelitian ini adalah larva Aedessp yang di ovitrap sebanyak 350 larva.
Hasil: Hasil penelitian menunjukkan bahwa efektifitas buah belimbing wuluh (Averrhoa bilimbiL.) kematian larva Aedes sp dalam waktu 24 jam dinyatakan tidak efektif pada konsentrasi 2%, 3%, dan 4% sedangkan yang dinyatakan efektif yaitu pada konsentrasi 5%, 6%, 7% dan 8%. Hasil perhitungan analisis probit didapatkan hasil bahwa nilai LC50 adalah 4,080% dan LC90 adalah 7,014%.
Kesimpulan: Belimbing wuluh efektif sebagai larvasida alami nyamuk Aedes sp.
Saran: Bagi masyarakat dapat menggunakan buah belimbing wuluh sebagai alternatif lain untuk pemberantasan nyamuk Aedes sp
Investigation of magnetization structures in ferromagnetic and superconducting samples by magnetic force microscopy
Even though the phenomenon of magnetic ordering in solids was already known to the
ancient Greek, the microscopic understanding of why certain materials show magnetic
order dates from this century. In particular, even though some form of magnetic domains
was already expected by Weiss when he formulated his theory of Ferromagnetic
ordering in 1907, direct experimental evidence of their existence was only provided
in 1931 by measurements of v. Hámod and Thiessen and Bitter. In these experiments,
the domain structure was determined by the imaging of small magnetic particles
that decorate regions with high magnetic stray fields. This decoration is due to the interaction
force between these particles and the sample stray field. Interestingly enough,
the reason why the domains were formed was still unclear, and was only clarified in
1935 by Landau and Lifschitz.
The phenomenon of Superconductivity on the other hand, was discovered much
more recently in 1911 by Kamerlingh Onnes. After its discovery, it took until 1933, when
Meissner and Ochsenfeld found that superconductors are ideal diamagnets, repelling
the magnetic flux from their inside, even if the field is applied before the superconductor
becomes superconductive. Again, the existence of domains was first predicted from the
theory published by Landau in 1937, but it took until the fifties before the first magnetic
flux structures in superconductors were imaged, again using the decoration technique.
Thus, even though the theoretical understanding of the domains in ferromagnets
and superconductors evolved almost simultaneously, the first direct observation of the
latter took 23 years longer, which was probably due to the experimental diffculties of
studying superconductors.
Magnetic force microscopy (MFM) is a relatively new technique for imaging these
magnetization structures. It combines the properties of the decoration technique (the
contrast formation is due the magnetic interaction between the stray field of the sample
and a small magnetic particle) with the properties of the scanning force microscopy
technique developed by Binnig, Quate and Gerber (measuring the interaction be-
tween the particle and the sample as a function of position through the deflection of
a cantilever beam). The first MFM measurements were made on ferromagnets.
Again, the first observation of magnetization structures in superconductors took somewhat
longer, until 1994. Nowadays with time and effort, the experimental diffculties
of working with MFM at low temperatures have been diminished by the development of
better instruments and improved measurement methods. The measurements presented
in this thesis were made with such an instrument, the design of which is discussed in
chapter 2.
Compared to other types of magnetic imaging,2 the advantages of the MFM technique
are a high spatial resolution imaging and relatively low requirements for sample
preparation. Another, unique property of the MFM is that it can be used as a tool for
determining the response of the sample to a local applied field and for modifying the
sample. One of the main disadvantages of the MFM until now has been the diffculty
to interpret the measured signal. In recent years, the improvement in the quality of
the instrument and the subsequent improvement of the measurement quality has allowed
the development of procedures that allow the quantitative interpretation of the
measured contrast. The methods developed for quantitative evaluation of the MFM
measurements as part of this thesis-work are described in more detail in chapter 3.
The application of the MFM method to the analysis of ferromagnetic materials is
described in chapter 4. A point of interest in the research of these materials is the
influence of the interfaces between ferromagnetic and other materials on the magnetic
properties of the sample. Here, this influence was studied using Cu/Ni/Cu/Si(001)
sandwich structures, because they show a particularly interesting dependence of the
preferred orientation of the magnetization on the thickness of the nickel layer.
Finally, the application of the MFM method to the study of superconductors is
described in chapter 5. In addition to the imaging of the magnetic structures occurring
in the superconductor, the use of the MFM to study the response of the superconductor
to a local applied field is discussed
Determination of the Rb ng-series quantum defect by electric-field-induced resonant energy transfer between cold Rydberg atoms
Resonant energy transfer between cold Rydberg atoms was used to determine
Rydberg atom energy levels, at precisions approaching those obtainable in
microwave spectroscopy. Laser cooled Rb atoms from a magneto-optical trap were
optically excited to 32d Rydberg states. The two-atom process 32d(j=5/2) +
32d(j=5/2) -> 34p(j=3/2) + 30g is resonant at an electric field of
approximately 0.3 V/cm. This process is driven by the electric dipole-dipole
interaction, which is allowed due to the partial f character that the g state
acquires in an electric field. The experimentally observed resonant field,
together with the Stark map calculation is used to make a determination of the
Rb ng-series quantum defect: delta_g (n=30) = 0.00405(6)
Characteristics of Wooden Furniture Drying Machine
This study aims to determine the characteristics of the electric energy drying machine used to dry wooden furniture. Furniture made of mahogany. The research was conducted experimentally in the wood furniture industry. The size of the wood drying room is 8 m x 6 m x 3 m. The dryer works with a vapor compression cycle using R134a freon and several fans placed in the drying chamber. The drying process uses a closed air system. The total volume of dried wooden furniture is 12.9 m3. The initial moisture content in the wood ranges from 18% to 23%. Wooden furniture is considered dry if the moisture content in the wood furniture is less than 12%. Research gives satisfactory results. The performance of the drying machine or COP is 10.85. The drying time for wooden furniture is about 72 hours
Assessing the Influence of the Imposter Phenomenon on Critical Leadership Competencies: Conceptual Framework Proposal
Will the imposter phenomenon influence critical leadership competencies, specifically decision-making self-efficacy, and innovative work behavior? This prospective study will propose a framework to investigate the impact of the imposter phenomenon on essential leadership skills, focusing on exploring whether self-esteem acts as a mediating factor. The research will seek to evaluate the potential effects of the imposter phenomenon on leadership competencies, such as innovative work behavior and decision-making self-efficacy, among managers in South Africa. The significance of this proposed investigation stems from a recognized gap in previous studies addressing the relationship between the imposter phenomenon and these leadership skills within the South African context. By adopting a quantitative approach through a cross-sectional correlational survey design, the study aims to achieve its objectives by testing hypotheses and addressing pertinent research questions. The target population will comprise managers from both the public and private sectors in South Africa, and purposeful sampling will be employed to ensure a representative sample of leaders and managers. Analytical tools will be used for data analysis, including descriptive statistics, Cronbach alpha coefficients, exploratory and confirmatory factor analyses, and structural equation modeling. The anticipated results are expected to reveal whether the imposter phenomenon has a detrimental effect on decision-making self-efficacy and innovative work behavior, with self-esteem as a mediating variable. The findings from this prospective study are anticipated to contribute to a heightened awareness of the imposter phenomenon, providing valuable insights for the better management and mitigation of its effects. The enhanced understanding of the imposter phenomenon can empower managers and leaders to make more effective decisions and exhibit innovative behavior
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