15,832 research outputs found
Bioassays for coastal water quality: an assessment using the larval development of Haliotis midae L
The United States Environmental Protection Agency (USEPA) has established a suite of methods that use coastal invertebrate species as bioassay organisms to test industrial and domestic effluent as well as coastal waters for potential toxicity. Although these methods are used globally, the potential of such toxicity tests has not been adequately explored for South African coastal waters. This study serves to describe a simple, cost-effective and relatively quick testing procedure using the development of Haliotis midae larvae as a bioassay of coastal water quality. This test is based on the sensitivity of these larvae to low concentrations of zinc (Zn). Its performance in a field trial demonstrates not only that this test has the potential to identify coastal waters of poor quality, but also that such identification could be of value in attempts to restock natural abalone populations, which are under extreme pressure from legal and illegal exploitation. Further work in this line should focus on the refinement of the methodology for this and other local species and should aim to contribute to the development of suitable criteria for the management of coastal water quality in South Africa.
WaterSA Vol.28(4) 2002: 457-46
VALUASI EKONOMI MANFAAT REKREASI TEBING KERATON DENGAN METODE TRAVEL COST METHOD
Jasa rekreasi hutan sebagai produk tambahan yang sifatnya intangible, tidak dapat dihitung secara
kuantitatif karena tidak memiliki harga pada sistem pasar normal. Hal ini mendasari penelitian untuk
mengetahui nilai ekonomi rekreasi, dengan studi kasus Tebing Keraton menggunakan metode
Individual Travel Cost Method. Analisis data dari kuesioner, menggunakan alat pengolah data SPSS
versi 21 dengan metode regresi linier berganda untuk mendapatkan fungsi permintaan rekreasi Tebing
Keraton. Variabel yang diduga berpengaruh terhadap jumlah kunjungan yaitu : biaya perjalanan (X1),
total pendapatan (X2), umur (X3), jarak tempuh (X4), dan jenis kelamin (X5). Nilai koefisien variabel
menentukan kecenderungan dalam meningkatkan atau menurunkan jumlah kunjungan wisata. Fungsi
permintaan rekreasi Tebing Keraton dibedakan menjadi dua yaitu fungsi rekreasi untuk
pelajar/mahasiswa dan untuk yang sudah bekerja dikarenakan perbedaan tolak ukur pada pendapatan
perbulan. Untuk memperoleh fungsi permintaan Tebing Keraton harus diketahui data-data variabel pada
model fungsi permintaan berdistribusi normal dengan uji normalitas. Berdasarkan hasil regresi
diperoleh fungsi permintaan rekreasi untuk pelajar/mahasiswa yaitu Y = -2,179 – 0,0000347 X1 + 0,286
X2 + 0.159 X3 - 0.0000794 X4 - 0.267 X5, dan yang sudah bekerja Y = 1,994 – 0,00000164 X1 + 0,53
X2 - 0.32 X3 - 0.003 X4 - 0.334 X5. Dari hasil regresi didapatkan nilai koefisien determinasi (R
) yaitu
persentase keragaman permintaan jumlah kunjungan ke Tebing Keraton yang dapat dijelaskan oleh
variabel-variabel bebas dalam model. Pada model fungsi permintaan rekreasi untuk pelajar/mahasiswa
R
2
2
sebesar 67,1% dan menurut ketetapan, terdapat pada rentang > 0,5 yaitu ketepatannya tinggi.
Sedangkan untuk yang sudah bekerja R
sebesar 48,9% terdapat pada rentang 0,31 - 0,5 yaitu
ketepatannya cukup. Surplus konsumen didapat sebesar Rp 22.863,00 per individu per kunjungan untuk
pelajar/mahasiswa. sebesar Rp 468.307,00 per individu per kunjungan untuk pekerja. Lalu dikalikan
dengan jumlah pengunjung dalam setahun didapat nilai ekonomi rekreasi Tebing Keraton untuk
pelajar/mahasiswa sebesar Rp. 1.603.585.014 dan nilai ekonomi Tebing Keraton untuk pekerja sebesar
Rp 21.898.035.320.
2
Kata kunci : fungsi permintaan rekreasi, regresi linier berganda, Tebing Keraton, variabe
It’s about time: A synthesis of changing phenology in the Gulf of Maine ecosystem
The timing of recurring biological and seasonal environmental events is changing on a global scale relative to temperature and other climate drivers. This study considers the Gulf of Maine ecosystem, a region of high social and ecological importance in the Northwest Atlantic Ocean and synthesizes current knowledge of (a) key seasonal processes, patterns, and events; (b) direct evidence for shifts in timing; (c) implications of phenological responses for linked ecological-human systems; and (d) potential phenology-focused adaptation strategies and actions. Twenty studies demonstrated shifts in timing of regional marine organisms and seasonal environmental events. The most common response was earlier timing, observed in spring onset, spring and winter hydrology, zooplankton abundance, occurrence of several larval fishes, and diadromous fish migrations. Later timing was documented for fall onset, reproduction and fledging in Atlantic puffins, spring and fall phytoplankton blooms, and occurrence of additional larval fishes. Changes in event duration generally increased and were detected in zooplankton peak abundance, early life history periods of macro-invertebrates, and lobster fishery landings. Reduced duration was observed in winter-spring ice-affected stream flows. Two studies projected phenological changes, both finding diapause duration would decrease in zooplankton under future climate scenarios. Phenological responses were species-specific and varied depending on the environmental driver, spatial, and temporal scales evaluated. Overall, a wide range of baseline phenology and relevant modeling studies exist, yet surprisingly few document long-term shifts. Results reveal a need for increased emphasis on phenological shifts in the Gulf of Maine and identify opportunities for future research and consideration of phenological changes in adaptation efforts
SISTEM PAKAR UNTUK INISIASI PENYELENGGARAAN RESEPSI PERNIKAHAN (Studi Kasus : Event Organizer Dot Of Corner, Bandung)
Sebuah pernikahan tidak pernah jauh dengan urusan sebuah resepsi, keduanya merupakan
serangkaian acara yang berkesinambungan. Dalam melaksanakan sebuah resepsi pernikahan di zaman
sekarang ini bukanlah hal yang mudah dimana setiap orang memiliki kesibukan yang sangat padat setiap
harinya. Hal yang perlu dipersiapkanpun tidaklah sedikit seperti sewa gedung, undangan, dokumentasi,
catering, pelaminan, dekorasi, perias, grup musik. Pada umumnya customer mencari informasi
mengenai perlengkapan pernikahan dan mendatangi langsung konsultan untuk berkonsultasi perihal
resepsi pernikahan. Sistem pakar untuk inisiasi penyelenggaraan resepsi pernikahan merupakan hal yang
penting mengingat proses inisiasi penyelenggaraan pernikahan di event organizer dot of corner masih
menggunakan cara konvensional. Permasalahan yang dijadikan titik tolak dalam pembuatan tugas akhir
ini adalah bagaimana cara meningkatkan kualitas layanan inisiasi penyelenggaraan pernikahan. Tujuan
dari tugas akhir ini adalah meningkatkan kualitas layanan inisiasi penyelenggaraan pernikahan dan
memberikan kenyamanan kepada customer dalam berkonsultasi.
Metodologi penelitian dilakukan dengan metode pengembangan sistem pakar ES DLC. Metode
akuisisi pengetahuan yang digunakan adalah metode manual dengan melakukan wawancara dan studi
literatur. Mesin inferensi pada sistem pakar ini dibangun dengan menggunakan metode forward
chaining. Untuk membangun sistem pakar ini menggunakan aplikasi sistem pakar yang sudah ada yaitu
Dexsys.
Hasil dari penelitian ini adalah aplikasi sistem pakar untuk berkonsultasi pada tahap inisiasi
penyelengaraan resepsi pernikahan yang memuat opsi budgeting, solusi, basis aturan dan rekomendasi
spesifikasi resepsi pernikahan. Berdasarkan hasil verifikasi dan validasi dapat disimpulkan bahwa
aplikasi sistem pakar ini dapat menjadi alat bantu untuk berkonsultasi perihal inisiasi penyelenggaraan
pernikahan.
Kata Kunci : Sistem Pakar, Inisiasi Penyelenggaraan Resepsi Pernikahan, Forward Chaining
Diversity has stronger top-down than bottom-up effects on decomposition
The flow of energy and nutrients between trophic levels is affected by both the trophic structure of food webs and the diversity of species within trophic levels. However, the combined effects of trophic structure and diversity on trophic transfer remain largely unknown. Here we ask whether changes in consumer diversity have the same effect as changes in resource diversity on rates of resource consumption. We address this question by focusing on consumer-resource dynamics for the ecologically important process of decomposition. This study compares the top-down effect of consumer (detritivore) diversity on the consumption of dead organic matter (decomposition) with the bottom-up effect of resource (detrital) diversity, based on a compilation of 90 observations reported in 28 studies. We did not detect effects of either detrital or consumer diversity on measures of detrital standing stock, and effects on consumer standing stock were equivocal. However, our meta-analysis indicates that reductions in detritivore diversity result in significant reductions in the rate of decomposition. Detrital diversity has both positive and negative effects on decomposition, with no overall trend. This difference between top-down and bottom-up effects of diversity is robust to different effect size metrics and could not be explained by differences in experimental systems or designs between detritivore and detrital manipulations. Our finding that resource diversity has no net effect on consumption in brown\u27\u27 (detritus-consumer) food webs contrasts with previous. ndings from green\u27\u27 (plant-herbivore) food webs and suggests that effects of plant diversity on consumption may fundamentally change after plant death
IDENTIFIKASI PENGARUH KUALITAS AIR SUNGAI TERHADAP KUALITAS AIR SUMUR DI RW 08 KELURAHAN BABAKAN CIAMIS KECAMATAN SUMUR BANDUNG KOTA BANDUNG BERDASARKAN PARAMETER BIOLOGIS E-COLI
Air merupakan kebutuhan paling vital bagi kehidupan manusia dan
makhluk hidup lainnya. Penyediaan air minum yang aman harus diupayakan
karena kemungkinan adanya pencemaran mikroorganisme pada air minum, seperti
pencemaran bakteri Escherichia coli (E.coli) yang menjadi indikator patogen
penyebab terjadinya diare. Menurut persyaratan Peraturan Menteri Kesehatan
Republik Indonesia Nomor 492/Menkes/Per/IV/2010 tentang persyaratan kualitas
air minum bahwa kadar maksimum bakteri E.coli untuk air minum yang
diperbolehkan dalam per 100 ml sampel adalah 0/100 ml. Tujuan dari penelitian
ini adalah untuk mengetahui ada atau tidaknya bakteri E.coli pada air sumur
warga RW 08 Kelurahan Babakan Ciamis dan berapa kadar MPN/100 ml serta
untuk mengetahui apakah terdapat hubungan bahwa jarak air sungai ke setiap
sumur, jarak toilet ke sumur dan kedalaman sumur mempengaruhi pencemaran air
sumur dengan mengguna kan metode regresi linier. Semua sampel positif
mengandung bakteri E.coli, dimana untuk nilai E.coli tertinggi adalah 210
MPN/100 ml dan terendah adalah 5,6 MPN/100 ml. Hubungan yang didapat
berdasarkan menggunakan Software Statistical Product and Service Solutions
(SPSS) didapat hubungan antara jarak sungai dengan sumur memiliki hubungan
keterkaitan yang sangat baik dibandingkan dengan variabel bebas lainnya dan
nilai yang didapat bernilai negatif, dimana dapat diartikan jika jarak dari sungai ke
setiap sumur dekat, maka bakteri E.coli akan tinggi begitu juga sebaliknya. Dan
variabel jarak dari sungai ke sumur ini berpengaruh signifikan karena nilai
Signifikansi hasil SPSS tidak melebihi 25% yaitu 0,052 atau 5,2% error nya.
Kata Kunci: Escherichia coli (E.coli), MPN, Regresi Linie
Bottom-Up versus Top-Down Induction of Sleep by Zolpidem Acting on Histaminergic and Neocortex Neurons
Zolpidem, a GABAA receptor-positive modulator, is the gold-standard drug for treating insomnia. Zolpidem prolongs IPSCs to decrease sleep latency and increase sleep time, effects that depend on α2 and/or α3 subunit-containing receptors. Compared with natural NREM sleep, zolpidem also decreases the EEG power, an effect that depends on α1 subunit-containing receptors, and which may make zolpidem-induced sleep less optimal. In this paper, we investigate whether zolpidem needs to potentiate only particular GABAergic pathways to induce sleep without reducing EEG power. Mice with a knock-in F77I mutation in the GABAA receptor γ2 subunit gene are zolpidem-insensitive. Using these mice, GABAA receptors in the frontal motor neocortex and hypothalamic (tuberomammillary nucleus) histaminergic-neurons of γ2I77 mice were made selectively sensitive to zolpidem by genetically swapping the γ2I77 subunits with γ2F77 subunits. When histamine neurons were made selectively zolpidem-sensitive, systemic administration of zolpidem shortened sleep latency and increased sleep time. But in contrast to the effect of zolpidem on wild-type mice, the power in the EEG spectra of NREM sleep was not decreased, suggesting that these EEG power-reducing effects of zolpidem do not depend on reduced histamine release. Selective potentiation of GABAA receptors in the frontal cortex by systemic zolpidem administration also reduced sleep latency, but less so than for histamine neurons. These results could help with the design of new sedatives that induce a more natural sleep
Antibacterial activity of watermelon (Citrullus lanatus) seed against selected microorganisms
This study was aimed at evaluating the effect of extraction methods on the antibacterial activity of Citrullus lanatus seed extract. C. lanatus (watermelon) is a popular fruit consumed all over the world. Three solvents were used for the extraction process: chloroform, methanol and distilled water while two extraction conditions- cold extraction and Soxhlet extraction (coded as hot in this study) were employed. Antibacterial activity of the seed extracts was determined by agar well diffusion method. The seed extracts were tested against clinical isolates including Staphylococcus sp., Escherichia coli, Proteus sp., Klebsiella sp. and a type Pseudomonas aeruginosa (ATCC 27853). It was observed that the cold methanol extracts had the highest antibacterial effect on Staphylococcus sp. followed by hotmethanol extract while cold chloroform extract showed no antibacterial activity. In the presence of P.aeruginosa only the hot methanol and chloroform extracts showed significant antibacterial potentials (p.0.05). Also, saponins which have been implicated in antimicrobial activity were found to be present in moderate and high concentrations in the hot and cold methanol extracts respectively. Results of this study reveal that the kind of solvent employed as well as the conditions for extraction (cold maceration and Soxhlet extraction) influenced the efficacy of the extract against specific test organisms. Furthermore, the presence of saponins may have influence the relatively high zone of inhibition recorded with coldand hot methanol extracts against some of the test organisms.Key words: Watermelon seed, antibacterial, Soxhlet extraction, cold maceration, solvents
Effect of social media in improving knowledge among patients having fixed appliance orthodontic treatment: A single-center randomized controlled trial
Research has shown that orthodontic patients are more likely to retain information presented in an audiovisual format. However, there has been little research on the effectiveness of audiovisual information provided through different routes such as the Internet. This parallel-group randomized controlled trial assessed whether provision of audiovisual information on the YouTube (Google, San Bruno, Calif) Web site to orthodontic patients undergoing fixed appliance treatment results in improved patient knowledge when compared with conventional methods of information provision. The effects of sex and ethnicity were also investigated
Individual differences in visual salience vary along semantic dimensions
What determines where we look? Theories of attentional guidance hold that image features and task demands govern fixation behavior, while differences between observers are interpreted as a “noise-ceiling” that strictly limits predictability of fixations. However, recent twin studies suggest a genetic basis of gaze-trace similarity for a given stimulus. This leads to the question of how individuals differ in their gaze behavior and what may explain these differences. Here, we investigated the fixations of >100 human adults freely viewing a large set of complex scenes containing thousands of semantically annotated objects. We found systematic individual differences in fixation frequencies along six semantic stimulus dimensions. These differences were large (>twofold) and highly stable across images and time. Surprisingly, they also held for first fixations directed toward each image, commonly interpreted as “bottom-up” visual salience. Their perceptual relevance was documented by a correlation between individual face salience and face recognition skills. The set of reliable individual salience dimensions and their covariance pattern replicated across samples from three different countries, suggesting they reflect fundamental biological mechanisms of attention. Our findings show stable individual differences in salience along a set of fundamental semantic dimensions and that these differences have meaningful perceptual implications. Visual salience reflects features of the observer as well as the image
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