ANALISIS DINAMIK MODEL PREDATOR- PREY DENGAN ADANYA PREY TERINFEKSI DAN KOMPETISI PADA PREDATOR

Pada artikel ini membahas model predator- prey  yang terdiri dari  dua  predator dan  satu prey dimana terdapat populasi prey terinfeksi dan kompetisi antara dua populasi predator, baik kompetisi intraspesifik ataupun kompetisi interspesifik, untuk memberikan pemahaman tentang dinamika sistem ekologi yang lebih kompleks secara matematis dengan menggunakan pemodelan sistem persamaan diferensial. Dilakukan analisis perilaku dinamis pada sistem, yang menunjukkan terdapat  sembilan titik ekuilibrium. Titik  ekuilibrium kepunahan selalu tidak stabil dan delapan titik ekuilibrium lainnya stabil asimtotik lokal dengan  beberapa kondisi. Dilakukan simulasi numerik untuk mendukung hasil analitik. Diberikan  diagram bifurkasi dengan menggunakan MatCont untuk menganalisis kestabilan sistem. Dengan  menvariasikan parameter  tingkat penyebaran penyakit,  diperoleh hasil adanya bifurkasi transkritikal  pada sistem. Kata kunci: model predator- prey, kestabilan  lokal, bifurkas

PENGARUH PERPUTARAN MODAL KERJA, PIUTANG DAN PERSEDIAAN TERHADAP PROFITABILITAS PADA INDUSTRI OTOMOTIF YANG TERDAFTAR DI BEI

Perusahaan didirikan dengan tujuan meningkatkan nilai perusahaan sehingga dapat memberikan kemakmuran bagi para pemegang atau pemilik saham. Salah satu upaya mencapai tujuannya, perusahaan selalu berusaha memaksimalkan labanya. Banyak faktor yang dapat mempengaruhi tingkat profitabilitas suatu perusahaan. Penelitian ini bertujuan untuk menganalisis ada tidaknya pengaruh dari variabel perputaran modal kerja, perputaran piutang, perputaran peseediaan tehadap profitabilitas industri otomotif yang terdaftar di bursa efek indonesia. Sampel penelitian ini adalah perusahaan otomotif yang terdaftar di Bursa Efek Indonesia tahun 2014-2018. Sampel diambil dengan menggunakan metode purposive sampling sehingga di peroleh 6 perusahaan yang memenuhi syarat sebagai sampel penelitian ini menggunakan metode analisis regresi linier berganda. Hasil penelitian ini menunjukkan bahwa variabel perputaran modal kerja berpengaruh Negatif tidak signifikan terhadap profitabilitas dan perputaran piutang berpengaruh positif tidak signifikan dan perputaran persediaan berpengaruh negatif signifikan terhadap profitabilita

Pengaruh Pemberian Ekstrak Pegagan (Centella asiatica) terhadap Kadar Trigliserida pada Tikus Model Hiperkolesterolemia

Latar Belakang - Hiperkolesterolemia adalah suatu keadaan ketika kadar kolesterol total atau kolesterol LDL di dalam darah lebih dari batas normalnya, yaitu >200 mg/dL. Hiperkolesterolemia dapat disebabkan karena meningkatnya kadar trigliserida (hipertrigliseridemia). Dibutuhkan alternatif terapi hipertrigliseridemia seperti menggunakan tanaman herbal untuk meminimalisir efek samping obat. Pegagan (Centella asiatica) mengandung berbagai zat aktif yang berpotensi menurunkan kadar trigliserida, seperti fenolik, polifenol, flavonoid, beta-karoten, tanin, vitamin C, dan triterpenoid. Tujuan - Mengetahui pengaruh pemberian ekstrak pegagan (Centella asiatica) terhadap kadar trigliserida pada tikus model hiperkolesterolemia. Metode Penelitian - Penelitian ini merupakan penelitian eksperimental rancangan acak lengkap terhadap hewan coba tikus (Rattus norvegicus) jantan strain Wistar dengan desain penelitian post-test only control group design. Penelitian ini menggunakan 35 tikus yang dibagi ke dalam 5 kelompok perlakuan, yang terdiri dari kelompok tikus sehat yang diberi pakan normal (P1), kelompok tikus hiperkolesterolemia yang diberi Na CMC 0,5% sebagai kontrol negatif (P2), serta kelompok tikus hiperkolesterolemia yang diberi ekstrak pegagan (Centella asiatica) dengan dosis 125 mg/kgBB/hari (P3), 250 mg/kgBB/hari (P4), dan 500 mg/kgBB/hari (P5). Induksi hiperkolesterolemia menggunakan kolesterol 2% dan asam kolat 0,2%. Hasil - Hasil analisis rata-rata kadar trigliserida pada masing-masing kelompok yaitu P1 sebesar 75,42 mg/dL, P2 sebesar 123,319 mg/dL, P3 sebesar 105,567 mg/dL, P4 sebesar 92,542 mg/dL, dan P5 sebesar 81,723 mg/dL. Analisis data dengan One Way ANOVA didapatkan nilai p=0,000 (p < 0,05) yang menunjukkan terdapatnya perbedaan bermakna antar kelompok perlakuan, kemudian dilanjutkan dengan uji LSD didapatkan p=0,000 (p < 0,05) pada semua kelompok yang menunjukkan terdapat perbedaan bermakna pada semua kelompok perlakuan. Kesimpulan - Pemberian ekstrak pegagan (Centella asiatica) dapat menurunkan kadar trigliserida secara bermakna pada dosis 125, 250, dan 500 mg/kgBB/hari, dimana dosis 500 mg/kgBB/hari merupakan dosis yang paling efektif dalam menurunkan kadar trigliserida pada tikus

Motivasi siswa pada penerapan metode Al-Qosimi pada program One Day One Ayat pengaruhnya terhadap hafalan Al-Qur'an: Penelitian pada siswa kelas VII SMP Negeri 01 Cileunyi

Berdasarkan dari studi pendahuluan diperoleh informasi bahwa motivasi siswa pada penerapan metode al-Qosimi pada program one day one ayat cukup tinggi. Namun disisi lain, ditemukan masih banyak siswa yang kemampuan hafalannya masih rendah. Hal tersebut menemukan kesenjangan dan sekaligus melahirkan permasalahan yang harus diteliti. Tujuan penelitian ini adalah untuk mengetahui: 1) Motivasi siswa pada penerapan metode al-Qosimi pada Program one day one ayat, 2) Hafalan al-Qur’an siswa, 3) Pengaruh motivasi siswa pada penerapan metode al-Qosimi pada program one day one ayat terhadap hafalan al-Qur’an siswa kelas VII SMP Negeri 01 Cileunyi. Penelitian ini didasarkan dari pemikiran bahwa kemampuan hafalan al-Qur’an siswa diperoleh banyak faktor. Salah satunya yaitu motivasi siswa pada penerapan metode al-Qosimi pada program one day one ayat. Berdasarkan penelitian ini maka hipotesis semakin tinggi motivasi siwa pada penerapan metode al-Qosimi pada program one day one ayat, maka hafalan al-Qur’an mereka akan semakin tinggi. Langkah-langkah penelitian ini adalah: 1) Pendekatan kuantitatif dan metode deskriptif, 2) Sumber penelitian adalah siswa SMPN 01 Cileunyi dengan populasi 500 diambil sampel 10% yaitu 50 orang, 3) Tempat dan waktu Penelitian di SMPN 01 Cileunyi dari tanggal 22 April s/d 22 November 2019, 4) Teknik pengumpulan data penelitian melalui angket, tes, wawancara, observasi, studi kepustakaan, dan 5) Teknik analisis data penelitian dengan analisis parsial dan korelasional. Berdasarkan hasil analisis data diperoleh kesimpulan 1) Motivasi siswa pada penerapan metode al-Qosimi pada Program one day one ayat termasuk pada kualifikasi positif, terbukti dengan rata-rata 3,89. Angka tersebut berada pada interval 3,40 – 4,19. 2) Hafalan al-Qur’an siswa pada kualifikasi tinggi, terbukti dengan rata-rata 77,98. Angka tersebut berada pada interval 70 – 79. 3) Motivasi siswa pada penerapan metode al-Qosimi pada program one day one ayat terhadap hafalan al-Qur’an siswa menghasilkan koefisien korelasi sebesar 0,142. Angka tersebut tergolong kategori sangat lemah, karena 0,142 berada pada skala 0,00-0,20 = Korelasi sangat lemah. Hasil perhitungan hipotesis dengan db=48 taraf signifikan 5% diperoleh hasil t_hitung< t_tabel atau 1,002 < 1,68. Hal ini membuktikan Ho diterima dan Ha ditolak. Artinya tidak ada hubungan yang signifikan antara Motivasi siswa pada penerapan metode al-Qosimi pada program one day one ayat terhadap hafalan al-Qur’an siswa. Derajat pengaruh variabel X terhadap variabel Y sebesar 2 %. Hal ini menunjukkan bahwa masih sangat banyak faktor lain yang mempengaruhi hafalan al-Qur’an sebesar 98 %

Mild cognitive impairment does not affect pattern electroretinogram in the elderly - a pilot study

The purpose of this study was to examine the effects of mild cognitive impairment on pattern electroretinogram (pERG) among urban elderly Malays. A total of 36 subjects aged 60 years and above comprising of 18 MCI subjects and 18 normal controls were recruited for this study. The inclusion criteria for both the MCI and normal subjects included best corrected distance visual acuity ≥ 6/9 (Snellen) with refractive error less than ±4.00 DS and/or ±2.00 DC (astigmatism), near visual acuity ≥ N8, absence or no previous history of any significant media opacities, retinal disorders and ocular pathologies. pERG was recorded with the RetiPort/Scan21 system in accordance with the International Society for the Clinical Electrophysiology of Vision standards. The target presented to subjects through a 19” CRT monitor was a black and white reversing checkerboard with luminance equal to 80 cd/m2, contrast 97% and stimulus frequency 2.00 Hz (4 rev/s). Amplitudes and implicit times of P50 and N95 waves generated by the system were noted and compared between the two groups. The results showed no significant difference in the amplitude and implicit times between the right and left eyes so only the right eye was used for comparison between the MCI and control groups. The mean amplitude and implicit times of the right eye of the MCI and control groups were 1.86±0.65 μV, 56.27±6.20 ms and 1.54±0.74 μV, 56.15±4.98 ms, respectively. T-test showed no significant differences in pERG amplitudes and implicit times between MCI and the control groups. In conclusion, our results may imply that the inner retina is intact in early MCI elderly subjects

Pattern Visual Evoked Potential (VEP) is unaffected in the early stage of mild cognitive impairment

The aim of this study was to determine whether pattern-reversal Visual Evoked Potential (PRVEP) is affected in mild cognitive impairment (MCI). Participants aged ≥ 60 years diagnosed as MCI were invited to participate in a study together with a group of controls. PRVEP was measured using A RETI-port/Scan 21 and stimuli of large and small checks sizes, 1° (60 min of arc) and 0.25° (15 min) respectively were used to obtain responses. The amplitude and implicit times of the MCI and control groups were then compared. A total of 18 MCI participants (age 65.7 ± 3.1 years) and 18 controls (65.1 ± 3.8 years) consented to participate in the study. The amplitude and implicit times for the MCI group using the target sizes of 60 min of arc were 9.80 ± 4.06 μV and 108.83 ± 7.63 ms and for 30 min of arc were 11.00 ± 7.44 μV and 123.96 ± 6.18 ms respectively. Consecutively for the control groups the amplitudes and implicit times were 8.96 ± 3.52μV, 105.85 ± 3.60 ms and 11.97± 6.11 μV, 122.57 ± 8.28 ms. PRVEP results did not reveal significant differences in P100-wave amplitude nor implicit time between the two groups under investigation. This study concluded that the visual pathway of MCI participants may be unaffected in the early part of the disease process

Characteristics of rambutan (Nephelium lappaceum L.) seed fat fractions and their potential application as cocoa butter improver

The utilization of rambutan seed (Nephelium Lappaceum L.) to produce fat (RSF) and its fractionation could be one of the solutions for better waste management and for ensuring its sustainable utilization. In this study, RSF was fractionated by two-stage acetone fractionation and their physicochemical properties such as fatty acid compositions, iodine value (IV), free fatty acid (FFA), slip melting point (SMP), and solid fat content (SFC) were investigated. The solid fraction-III (F2-S) exhibited the highest SMP (49.03°C) and lowest IV (27.57 g I2/100 g). The major fatty acids in all solid fractions were stearic (15.1- 21.6%), oleic (25.0-35.5%), and arachidic (42.7-46.9%) acids. The SFC of F2-S at 20°C (78.57%) and 35°C (22.95%) were found to be higher than solid fraction-I (F1-S), indicating a harder solid fraction. This study revealed that by performing fractionation of RSF, a cocoa butter improvers (CBI) could be prepared by blending them with other fats that have the potential to be utilized in chocolate manufacturing in tropical countries

Functional and nutritional properties of rambutan (Nephelium lappaceum L.) seed and its industrial application: A review

Background Rambutan (Nephelium lappaceum L.) is an important commercial fruit in southeast Asia and is gaining more attention in recent years because it is juicy and sweet and has a refreshing flavour and an exotic appearance. It is commercialized for fresh consumption and is industrially processed as canned fruit, juices, jams, jellies, marmalades, and spreads. The seed is a major co-product of this industry and is worthy of attention for industrial applications and their feasibility. Scope and approach This review describes the composition of the rambutan seed, which is examined from a critical interpretation regarding the suitable use of this co-product. This review also compares the total yield, physicochemical and thermal properties of its fat for the purpose of evaluating the potential of this fruit co-product as a source of natural edible fat with potential industrial uses. Key findings and conclusions Rambutan seed is a major co-product of the industry that has high premium-grade fat, protein, carbohydrate, fibre, antioxidants, and phenolic content and that can be used in several segments of the food, pharmaceutical, and cosmetic industries. Rambutan seed powders are also used as local medicine (they contain antidiabetic compounds) in Malaysia. To determine the effectiveness of raw rambutan seeds in treating diseases, in vivo and human clinical studies should be performed. Research should also continue to determine if rambutan seed fat can be fractionated, chemical and enzymatic interesterified, and blended with other fats to make cocoa butter alternatives. Comprehensive studies are needed on rambutan seed to explore more potential industrial applications

Functional and nutritional properties of rambutan (Nephelium lappaceum L.) seed and its industrial application: A review

Background Rambutan (Nephelium lappaceum L.) is an important commercial fruit in southeast Asia and is gaining more attention in recent years because it is juicy and sweet and has a refreshing flavour and an exotic appearance. It is commercialized for fresh consumption and is industrially processed as canned fruit, juices, jams, jellies, marmalades, and spreads. The seed is a major co-product of this industry and is worthy of attention for industrial applications and their feasibility. Scope and approach This review describes the composition of the rambutan seed, which is examined from a critical interpretation regarding the suitable use of this co-product. This review also compares the total yield, physicochemical and thermal properties of its fat for the purpose of evaluating the potential of this fruit co-product as a source of natural edible fat with potential industrial uses. Key findings and conclusions Rambutan seed is a major co-product of the industry that has high premium-grade fat, protein, carbohydrate, fibre, antioxidants, and phenolic content and that can be used in several segments of the food, pharmaceutical, and cosmetic industries. Rambutan seed powders are also used as local medicine (they contain antidiabetic compounds) in Malaysia. To determine the effectiveness of raw rambutan seeds in treating diseases, in vivo and human clinical studies should be performed. Research should also continue to determine if rambutan seed fat can be fractionated, chemical and enzymatic interesterified, and blended with other fats to make cocoa butter alternatives. Comprehensive studies are needed on rambutan seed to explore more potential industrial applications

Effects of drying methods on the characteristics of rambutan (Nephelium lappaceum L.) seed fat: an optimisation approach

The pre-treatment of oilseeds prior to extraction process may affect oil yield and quality. The aim of this study was to investigate the effects of two drying methods on rambutan seed fat (RSF) yield and their oxidative stability, physicochemical properties, and crystal morphology. Response surface methodology (RSM) was used in the optimisation and investigation of the effects of three process conditions: seed weight (g), extraction time (min), and solvent volume (ml) on RSF yield. Under optimal conditions, a maximum RSF yield of 44.14% was obtained. The differences between RSF pre-treated with oven-drying and RSF with freeze-drying methods in slip melting point (38.3◦C to 39.7◦C), free fatty acid (3.13 to 3.50 mg KOH/g fat), peroxide value (1.04 to 1.67 meq of O2/kg of fat), p-anisidine value (1.10 to 1.56), and total oxidation value (4.21 to 5.67) were significant (p < 0.05). Both fats showed needle-like shaped crystals. Our results provide usefu linformation in the pre-treatment of RSF, which has potential to be used as blending component with palm oil for cocoa butter equivalent formulation in chocolate and confectionery industries