Potency of Vibrio Isolates for Biocontrol of Vibriosis in Tiger Shrimp (Penaeus Monodon) Larvae

This study was carried out to obtain Vibrio isolates able to function as biocontrol of vibriosis in shrimp hatchery. Thirty one Vibrio isolates were isolated from tiger shrimp larvae and hatchery environments, i.e. Labuan, Pangandaran, and Lampung, Indonesia. Pathogenic V. harveyi MR5339 was obtained from Maros, South-Sulawesi and was made as a rifampicin resistant mutant (RFR) to screen for those 31 Vibrio isolates in in vitro assays and to allow us to monitor their presence in shrimp larvae and larval rearing water. Almost all Vibrio isolates could inhibit the growth of pathogenic V. harveyi MR5339 RFR. SKT-b isolate from Skeletonema was the most effective to inhibit the growth of V. harveyi MR5339 Rf* and significantly reduced larval mortality in pathogen challenge assays. These prospective biocontrol bacteria, at concentration of 10" CFU/ml, did not show pathogenicity to shrimp larvae. SKT-b was Gram negative, short rod-shape, exhibited yellow colonies on TCBS and swarming on SWC-agar media, motile, utilized glucose and sucrose but not lactose: produced extra-cellular protease and amylase, but did not produce chitmase. Partial sequencing of 16S-rRNA gene SKT-b showed SKT-b similarity to Vibrio alginofyticus

POTENCY OF VIBRIO ISOLATES FOR BIOCONTROL OF VIBRIOSIS IN TIGER SHRIMP (PENAEUS MONODON) LARVAE

This study was carried out to obtain Vibrio isolates able to function as biocontrol of vibriosis in shrimp hatchery. Thirty one Vibrio isolates were isolated from tiger shrimp larvae and hatchery environments, i.e. Labuan, Pangandaran, and Lampung, Indonesia. Pathogenic  V. harveyi MR5339 was obtained from Maros, South-Sulawesi and was made as a rifampicin resistant mutant (RFR) to screen for those 31 Vibrio isolates in in vitro assays and to allow us to monitor their presence in shrimp larvae and larval rearing water. Almost all Vibrio  isolates could inhibit the growth of pathogenic V. harveyi MR5339 RFR. SKT-b isolate from Skeletonema was the most effective to inhibit the growth of V. harveyi MR5339 Rf* and significantly reduced larval mortality in pathogen challenge assays. These prospective biocontrol bacteria, at concentration of 10" CFU/ml, did not show pathogenicity to shrimp larvae. SKT-b was Gram negative, short rod-shape, exhibited yellow colonies on TCBS and swarming on SWC-agar media, motile, utilized glucose and sucrose but not lactose: produced extra-cellular protease and amylase, but did not produce chitmase. Partial sequencing of 16S-rRNA gene SKT-b showed SKT-b similarity to Vibrio alginofyticus. Keywords: shrimp larvae / biocontrol bacteria / vibriosis

Nitrifikasi Dalam Biodegradasi Limbah Tambak

Penelitian ini bertujuan untuk mengetahui laju nitrifikasi dan bakteri yang paling efektif membentuk nitrat dalam biodegradasi limbah tambak udang. Percobaan dilakukan dengan 6 perlakuan dan 3 ulangan dengan media percobaan limbah tambak biasa dan limbah tambak steril. Hasil percobaan memperlihatkan bahwa semakin tinggi kadar OSS dalam media percobaan, laju nitrifikasi semakin rendah, tetapi populasi mikroba nitrifikasi semakin tinggi. Laju nitrifikasi berkisar antara 0.0059 – 0.0089 ppm/hari, dengan laju tertinggi diperoleh pada perlakuan T2 (kadar TSS 200 ppm, OSS 147.30 ppm, amonia 0.22 ppm) dan terendah pada perlakuan T0 (kadar TSS 100 ppm, OSS 58.20 ppm, amonia 0.19 ppm). Bakteri nitrifikasi yang paling efektif membentuk nitrat dalam media percobaan adalah Nitrococcus sp. untuk perlakuan T0 dan T1, Nitrospira sp.untuk perlakuan T2 dan T3, dan Nitrobacter sp. untuk perlakuan T4 dan T5. Dalam media limbah tambak steril, laju nitrifikasi setiap jenis bakteri berkisar antara 0.0039 – 0.0069 ppm/hari dengan tingkat efektivitas rata-rata 72.02%. Bakteri yang paling efektif membentuk nitrat dalam biodegradasi limbah tambak udang adalahNitrospira marina

The Purpose of This Research is to Built a Water Quality Model Which Explains DO-BOD Responsse as the Effect of Organic Loading by Hydrodynamic Behavior, Chemical and Biological Processes in the Stream Which Are Developed Mathematically From Reoxygenation Rate (Ka), Deoxygenation Rate (Kd), Photosynthesis and Respiration, Sediment Oxygen Demand (SOD) That Are Got From Laboratory Analysis and Direct Measuring in the Field. the Research Was Done in Laboratory Using Standard Method and Also Done in Field When Rainy and Dry Season. Parameters That Were Measured Are Water Temperature, PH, BOD, DO, Discharge, Velocity, and Water Depth. Based on the Research, DO-BOD Responsse Observation Has a Same Tendency with the Result of Model. Key Words: Hydrodinamic, Reoxygenation Rate, Decomposition Rate, DO-BOD Responsse

The purpose of this research is to built a water quality model which explains DO-BOD responsse as the effect of organic loading by hydrodynamic behavior, chemical and biological processes in the stream which are developed mathematically from reoxygenation rate (ka), deoxygenation rate (kd), photosynthesis and respiration, sediment oxygen demand (SOD) that are got from laboratory analysis and direct measuring in the field. The research was done in laboratory using standard method and also done in field when rainy and dry season. Parameters that were measured are water temperature, pH, BOD, DO, discharge, velocity, and water depth. Based on the research, DO-BOD responsse observation has a same tendency with the result of model

Spontaneous Interlayer Charge Transfer near the Magnetic Quantum Limit

Experiments reveal that a confined electron system with two equally-populated layers at zero magnetic field can spontaneously break this symmetry through an interlayer charge transfer near the magnetic quantum limit. New fractional quantum Hall states at unusual total filling factors such as \nu = 11/15 (= 1/3 + 2/5) stabilize as signatures that the system deforms itself, at substantial electrostatic energy cost, in order to gain crucial correlation energy by "locking in" separate incompressible liquid phases at unequal fillings in the two layers (e.g., layered 1/3 and 2/5 states in the case of \nu = 11/15).Comment: 4 pages, 4 figures (1 color) included in text. Related papers at http://www.ee.princeton.edu/~hari/papers.htm

Involuntary psychiatric hospitalisation, stigma stress and recovery: a 2-year study

AIMS Compulsory admission can be experienced as devaluing and stigmatising by people with mental illness. Emotional reactions to involuntary hospitalisation and stigma-related stress may affect recovery, but longitudinal data are lacking. We, therefore, examined the impact of stigma-related emotional reactions and stigma stress on recovery over a 2-year period. METHOD Shame and self-contempt as emotional reactions to involuntary hospitalisation, stigma stress, self-stigma and empowerment, as well as recovery were assessed among 186 individuals with serious mental illness and a history of recent involuntary hospitalisation. RESULTS More shame, self-contempt and stigma stress at baseline were correlated with increased self-stigma and reduced empowerment after 1 year. More stigma stress at baseline was associated with poor recovery after 2 years. In a longitudinal path analysis more stigma stress at baseline predicted poorer recovery after 2 years, mediated by decreased empowerment after 1 year, controlling for age, gender, symptoms and recovery at baseline. CONCLUSION Stigma stress may have a lasting detrimental effect on recovery among people with mental illness and a history of involuntary hospitalisation. Anti-stigma interventions that reduce stigma stress and programs that enhance empowerment could improve recovery. Future research should test the effect of such interventions on recovery

Quantum Hall effect in single wide quantum wells

We study the quantum Hall states in the lowest Landau level for a single wide quantum well. Due to a separation of charges to opposite sides of the well, a single wide well can be modelled as an effective two level system. We provide numerical evidence of the existence of a phase transition from an incompressible to a compressible state as the electron density is increased for specific well width. Our numerical results show a critical electron density which depends on well width, beyond which a transition incompressible double layer quantum Hall state to a mono-layer compressible state occurs. We also calculate the related phase boundary corresponding to destruction of the collective mode energy gap. We show that the effective tunneling term and the interlayer separation are both renormalised by the strong magnetic field. We also exploite the local density functional techniques in the presence of strong magnetic field at $\nu=1$ to calculate renormalized $\Delta_{SAS}$. The numerical results shows good agreement between many-body calculations and local density functional techniques in the presence of a strong magnetic field at $\nu=1$. we also discuss implications of this work on the $\nu=1/2$ incompressible state observed in SWQW.Comment: 30 pages, 7 figures (figures are not included