Judul: Correlation between Digit Ratio (2D:4D) with Hand Grip Strength in Indonesian Adult Men
Abstrak: Rasio digit jari 2D:4D merupakan biomarker alami yang telah banyak digunakan untuk mengetahui paparan hormon testosteron prenatal yang dapat berpengaruh terhadap tingginya peforma kekuatan seseorang. Rasio ini juga mempengaruhi hal- hal lain seperti tinggi badan dan kekuatan tangan. Namun, di Indonesia penelitian mengenai keterkaitan ini masih sedikit dilaporkan. Oleh karena itu, penelitian ini bertujuan mengetahui pengaruh rasio digit jari 2D:4D terhadap kekuatan genggaman tangan (Hand Grip Strength) pada laki-laki dewasa Indonesia. Hasil penelitian menunjukkan rasio digit jari (2D:4D) memiliki korelasi negatif terhadap kekuatan genggaman pada kedua tangan, yang dapat diartikan semakin rendah rasio digit jari maka semakin tinggi kekuatan genggaman. Beberapa faktor lain seperti tinggi badan, berat badan serta BMI juga memiliki korelasi positif yang signifikan terhadap kekuatan genggaman. Namun, hanya faktor umur yang tidak memiliki pengaruh yang signifikan dikarenakan tidak meratanya kisaran umur sampel yang diambil., The 2D:4D digit ratio is a natural biomarker that has been widely used to determine prenatal testosterone exposure, which can affect a person's high strength performance. This ratio also affects other factors, such as height and hand strength. However, research on this linkage in Indonesia is still limited. Therefore, this study aims to determine the effect of the 2D:4D digit ratio on hand grip strength in Indonesian adult men. The results showed a negative correlation between the finger digit ratio (2D:4D) and grip strength in both hands, indicating that a lower finger digit ratio corresponds to higher grip strength. Several other factors, including height, weight, and BMI, also showed a significant positive correlation with grip strength. However, the age factor had no significant effect due to the uneven age range of the sampled individuals.
Keyword: biomarkers, finger digit ratio, hand grip strength, testosterone

Judul: Correlation between Digit Ratio (2D:4D) and Physical Profile Factors on Hand Grip Strength (HGS) in College Students at IPB University
Abstrak: Digit ratio 2D:4D merupakan biomarker yang digunakan untuk melihat suatu karakter melalui gen yang ekspresinya dipengaruhi oleh jenis kelamin. Digit rasio seringkali dihubungkan dengan kekuatan genggaman. Penelitian sebelumnya menunjukkan korelasi antara digit ratio dengan kekuatan genggaman tangan pada laki-laki, sedangkan belum banyak dilakukan pada perempuan. Penelitian ini bertujuan menguji korelasi antara digit rasio dengan kekuatan genggaman tangan pada perempuan dewasa. Penelitian ini telah dilaksanakan pada bulan November 2023, dengan 250 partisipan mahasiswi di IPB University pada rentang usia 17-25 tahun. Jangka sorong digunakan untuk mengukur rasio digit (2D:4D) dan Hand grip-D Device akan digunakan untuk mengukur kekuatan genggaman tangan. Data dianalisis dengan perangkat lunak R studio. Korelasi antara digit rasio (2D:4D), kekuatan genggaman tanagn, dan faktor profil fisik dianalisis dengan uji korelasi spearman. Studi ini menunjukkan bahwa digit rasio mahasiswi di IPB University memiliki rata-rata rasio (=1) untuk kedua tangan. Digit rasio 2D:4D tidak memiliki hubungan yang signifikan dengan kekuatan genggaman tangan (kanan: p= - 0.00039, p-value= 0.95; kiri: p= 0.0217, p-value= 0.73). faktor lain yang diamati, seperti berat badan, tinggi badan, dan BMI menunjukkan korelasi yang signifikan dengan kekuatan denggaman tangan. Kata kunci : Biomarker, digit rasio 2D:4D, kekuatan genggaman tangan, korelasi, perempuan, Digit ratio 2D:4D is a biomarker used to see a character through genes whose expression is influenced by gender. Digit ratio is often associated with grip strength. Previous studies have shown a correlation between digit ratio and hand grip strength in men, while not much has been done in women. This study aims to examine the correlation between digit ratio and hand grip strength in adult women. This study was conducted in November 2023, with 250 female participants at IPB University in the age range of 17-25 years. A caliper was used to measure digit ratio (2D:4D) and Hand grip-D Device will be used to measure hand grip strength. Data were analyzed with R studio software. Correlations between digit ratio (2D:4D), hand grip strength, and physical profile factors were analyzed by Spearman correlation test. This study shows that digit ratio students at IPB University have an average ratio (=1) for both hands. Digit ratio 2D:4D had no significant relationship with hand grip strength (right: p= -0.00039, p-value = 0.95; left: p= 0.0217, p-value = 0.73). Other observed factors, such as weight, height, and BMI showed significant correlation with hand grip strength. Keywords: Biomarkers, 2D:4D digit ratio, handgrip strength, correlation, female
Keyword: biomarker, correlation, 2D:4D digit ratio, handgrip strength, female

Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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