Modelling the Dynamics of a Renewable Resource under Harvesting with Taxation as a Control Variable

The present paper describes a model of resource biomass and population with a non-linear catch rate function on resource biomass. The harvesting effort is assumed to be a dynamical variable. Tax on per unit harvested resource biomass is used as a tool to control exploitation of the resource. Pontryagin’s Maximum Principle is used to find the optimal control to maintain the resource biomass and population at an optimal level. A numerical simulation is also carried out to support the analytical results

Low current Cd4+T cell count: prediction, for persistent herpetic gingivostomatitis in HIV-positive patients under antiretroviral therapy

Background: Oral viral lesions associated with HIV infection are important since they affect the quality of life of the patient and are useful markers of disease progression and immunosuppression. The purpose of this study was to correlate the persistence of herpetic gingivostomatitis lesions with the current CD4+ T cell count for adherence of HIV-infected individuals to anti retroviral therapy (ART) and antiviral therapy.Methods: 302 HIV +ve patients developing oral ulcers were included in this study. The herpes simplex viral infections associated with the oral manifestations were detected through Immuno histochemical staining. The quantitative analysis of oral ulceration was done by using mucositis index.CD4T cell count was correlated with clinical manifestations of extensiveness of oral ulcers, acute febrile condition and other constitutional symptoms during follow up of cases for the treatment with anti viral therapies.Results: Association of herpes simplex viral infections was found in 72 out of 302 HIV+ ve cases. All the HSV +ve patients developed extensive oral mucsal lesions during the 1st week. Extensive lesions developed within 7 days in patients with CD4 count 500, manifestation of mucosal ulcers due to acute herpetic gingivostomatitis was limited to a period of 1 to 2 weeks. Patients with CD4 count >200 <500 did not follow a definite pattern.Conclusions: Persistent oropharyngeal mucosal ulcers along with acute febrile condition due to herpes simplex virus infection are associated with low CD4 T cell count in HIV + patients under antiretroviral therapy

Study of Radiophotoluminescence of Eu Doped CaSO4 Phosphor for Gamma Dosimetric Applications

CaSO4:Eu phosphor is synthesised by acid distillation method with varying synthesis parameters for studying its Radiophotoluminescence (RPL) properties for gamma absorbed dose measurements. Five phosphor samples are prepared by varying quantity of solvent, distillation temperature and reaction time. XRD, SEM, particle size analysis and photoluminescence studies are carried out. The characterisation study shows polycrystalline luminescent particles of average size varying from 35 μm to 55 μm. Characteristic emission of Eu3+ is observed around 590, 615 and 620 nm at 242 nm excitation. Gamma dose response of maximum Eu3+ PL intensity sample is studied in the range 10 cGy to 1000 cGy using Co-60 source. Gamma radiation exposure induces conversion of Eu3+ to Eu2+ giving luminescence at 385 nm with 320 nm excitation. Repetitive measurements of gamma exposed samples are carried out and no significant fading is observed within one week of post-irradiation. The phosphor has the potential to be used for gamma dosimetry

The need for calcium imaging in nonhuman primates: New motor neuroscience and brain-machine interfaces

A central goal of neuroscience is to understand how populations of neurons coordinate and cooperate in order to give rise to perception, cognition, and action. Nonhuman primates (NHPs) are an attractive model with which to understand these mechanisms in humans, primarily due to the strong homology of their brains and the cognitively sophisticated behaviors they can be trained to perform. Using electrode recordings, the activity of one to a few hundred individual neurons may be measured electrically, which has enabled many scientific findings and the development of brain-machine interfaces. Despite these successes, electrophysiology samples sparsely from neural populations and provides little information about the genetic identity and spatial micro-organization of recorded neurons. These limitations have spurred the development of all-optical methods for neural circuit interrogation. Fluorescent calcium signals serve as a reporter of neuronal responses, and when combined with post-mortem optical clearing techniques such as CLARITY, provide dense recordings of neuronal populations, spatially organized and annotated with genetic and anatomical information. Here, we advocate that this methodology, which has been of tremendous utility in smaller animal models, can and should be developed for use with NHPs. We review here several of the key opportunities and challenges for calcium-based optical imaging in NHPs. We focus on motor neuroscience and brain-machine interface design as representative domains of opportunity within the larger field of NHP neuroscience

F(T) Models within Bianchi Type I Universe

In this paper, we consider spatially homogenous and anisotropic Bianchi type I universe in the context of F(T) gravity. We construct some corresponding models using conservation equation and equation of state parameter representing different phases of the universe. In particular, we take matter dominated era, radiation dominated era, present dark energy phase and their combinations. It is found that one of the models has a constant solution which may correspond to the cosmological constant. We also derive equation of state parameter by using two well-known F(T) models and discuss cosmic acceleration.Comment: 19 pages, accepted for publication in Mod. Phys. Lett.

Human African Trypanosomiasis and challenges to its control in Urambo, Kasulu and Kibondo Districts, western Tanzania

A study was carried out to determine the prevalence and management of Human African Trypanosomiasis (HAT) in Urambo, Kasulu and Kibondo districts of western Tanzania. Parasitological surveys for trypanosome and other blood parasites were conducted in selected villages. Interviews with health workers were conducted to explore facility capacity to diagnose and manage HAT. Community knowledge on tsetse and availability of trypanocidal drugs was explored. Results showed that, although health facility records showed HAT is an important public health problem in the three districts, typanosomes were found in 0.6% of the examined individuals in Urambo district only. Malaria parasites with a prevalence of 12.1%, 19.7% and 9.7%, in Urambo, Kibondo and Kasulu, respectively were detected in blood samples from the same individuals examined for trypanosomes. There was poor capacity for most of the health facilities in the diagnosis, treatment and control of HAT. In both districts, communities were knowledgeable of the tsetse identity (82.4%) and had experienced tsetse bites (94%). The majority (91.4%) of the community members knew that they were at risk of acquiring HAT. However, only 29% of the respondents knew that anti-trypanocidal drugs were readily available free of charge from health care facilities. Late treatment seeking behaviour was common in Kasulu and Urambo districts. In conclusion, health facilities in western Tanzania are faced with problems of poor capacity to diagnose and manage HAT and that treatment seeking behaviour among the communities at risk is poor. Efforts should be made to strengthen the capacity of the health facility to handle HAT cases and health education to the population at risk. Keywords: Human African Trypanosomiasis, diagnosis, control, TanzaniaTanzania Health Research Bulletin Vol. 8 (2) 2006: pp. 80-8

Ultrazvučna procjena reakcije jajnika nakon primjene mjera svjetlosnoga režima u deva (Camelus dromedarius).

The present study was carried out with two objectives, (a) the use of ultrasound scanners to study the effect of ‘mask on eyes’ as a photoperiodic control measure for folliculogenesis in female camels, (b) Use of blood progesterone assays to monitor ovarian changes in camels. Fourteen female camels aged 7-11 years were used for the present experiment. Seven were studied for the effect of a mask over the eyes (for six hours daily) as a photoperiodic control measure on ovarian activity and the remaining seven were kept as controls. Ovaries were examined by ultrasound at weekly intervals for seven weeks during the non-breeding season. Camels were mated with virile stud when a follicle (≥0.9 cm diameter, ovulating size) was visible on either of the ovaries. Ovaries were monitored for ovulation up to 48 h post-mating by ultrasound at 12 hourly intervals and at 20, 30 and 40 days post mating to ascertain pregnancy. A commercially available RIA kit was used for serum progesterone assay on samples obtained at 0, 7, 15, 30 and 45 days of mating. No follicle was observed in camels before treatment and in treated (masked) or untreated camels during the first week of treatment. By the third week 100% camels in the treatment group evidenced measurable small follicles (0.5-0.89 cm, 6/7) or follicles of ovulating size (≥0.9 cm, 1/7). Follicles of ovulating size were observed in 28.6, 14.3, 14.3 and 14.3 percent camels by 4th, 5th, 6th and 7th week of treatment. Fifty percent (3/6) of the camels became pregnant. The serum plasma progesterone level increased after ovulation and remained higher than 1.0 ng/mL in pregnant camels. In the control group one camel showed a follicle (0.6 cm diameter) at the 5th week, which did not reach ovulating size. The results of the present study indicate that protecting eyes from sunlight one or two months ahead of the breeding season stimulates follicular growth in camels and pregnancy can occur in these camels when mated.Istraživanje je provedeno u svrhu ultrazvučnoga praćenja utjecaja svjetlosnoga razdoblja kontroliranog pomoću maske na očima na tijek i dinamiku folikulogeneze u deva i određivanja razine progesterona za praćenje cikličnih promjena na jajnicima. Promatrano je 14 deva u dobi od sedam do 11 godina koje su bile podijeljene u pokusnu (n = 7) i kontrolnu skupinu (n = 7). Devama u kontrolnoj skupini svakodnevno je stavljana maska na oči tijekom 6 sati u razdoblju od 7 tjedana izvan rasplodne sezone. Deve su ultrazvučno pregledavane jednom tjedno za vrijeme čitavoga trajanja istraživanja. One su bile parene s plodnim mužjakom kad je uočen folikul na jajniku (≥0,9 cm promjera, ovulacijski folikul). Kad je uočen ovulacijski folikul, jajnici su bili pregledavani ultrazvukom svakih 12 sati u razdoblju od 48 sati radi potvrđivanja ovulacije, a potom nakon 20, 30 i 40 dana radi potvrđivanja gravidnosti. Uzorci krvi bili su uzeti 0., 7., 15., 30. i 45. dana nakon parenja, a plazma je bila analizirana komercijalnim RIA kompletom za određivanje koncentracije progesterona. Prije početka istraživanja i tijekom prvog tjedna istraživanja nijedna deva nije imala folikule na jajnicima. Do trećega tjedna istraživanja, uočeni su folikuli u svih deva pokusne skupine, ali su većinom bili maloga promjera (0,5 - 0,89 cm, 6/7), osim u jedne deve u koje je folikul bio ovulacijske veličine (>0,9 cm). Folikuli koji su po veličini odgovarali ovulacijskim folikulima ustanovljeni su u 28,6% deva tijekom 4. tjedna, 14,3% tijekom 5. tjedna, 14,3% tijekom 6. i 14,3% deva tijekom 7. tjedna istraživanja. Koncipiralo je 50% deva (3/6). Razina progesterona u krvi porasla je nakon ovulacije i bila je veća od 1 ng/ml u svih gravidnih deva. U kontrolnoj skupini samo je jedna deva imala folikul (0,6 cm) na jajniku tijekom 5. tjedna, ali on nije dosegnuo ovulacijsku veličinu. Rezultati istraživanja pokazuju da zaštita očiju od svjetlosti mjesec do dva prije sezone parenja potiče razvoj folikula u deva i može dovesti do gravidnosti ako se deve tada par

A Universal Marginalizer for Amortized Inference in Generative Models

We consider the problem of inference in a causal generative model where the set of available observations differs between data instances. We show how combining samples drawn from the graphical model with an appropriate masking function makes it possible to train a single neural network to approximate all the corresponding conditional marginal distributions and thus amortize the cost of inference. We further demonstrate that the efficiency of importance sampling may be improved by basing proposals on the output of the neural network. We also outline how the same network can be used to generate samples from an approximate joint posterior via a chain decomposition of the graph

MicroRNAs targeting oncogenes are down-regulated in pancreatic malignant transformation from benign tumors

BACKGROUND MicroRNA (miRNA) expression profiles have been described in pancreatic ductal adenocarcinoma (PDAC), but these have not been compared with pre-malignant pancreatic tumors. We wished to compare the miRNA expression signatures in pancreatic benign cystic tumors (BCT) of low and high malignant potential with PDAC, in order to identify miRNAs deregulated during PDAC development. The mechanistic consequences of miRNA dysregulation were further evaluated. METHODS Tissue samples were obtained at a tertiary pancreatic unit from individuals with BCT and PDAC. MiRNA profiling was performed using a custom microarray and results were validated using RT-qPCR prior to evaluation of miRNA targets. RESULTS Widespread miRNA down-regulation was observed in PDAC compared to low malignant potential BCT. We show that amongst those miRNAs down-regulated, miR-16, miR-126 and let-7d regulate known PDAC oncogenes (targeting BCL2, CRK and KRAS respectively). Notably, miR-126 also directly targets the KRAS transcript at a "seedless" binding site within its 3'UTR. In clinical specimens, miR-126 was strongly down-regulated in PDAC tissues, with an associated elevation in KRAS and CRK proteins. Furthermore, miR-21, a known oncogenic miRNA in pancreatic and other cancers, was not elevated in PDAC compared to serous microcystic adenoma (SMCA), but in both groups it was up-regulated compared to normal pancreas, implicating early up-regulation during malignant change. CONCLUSIONS Expression profiling revealed 21 miRNAs down-regulated in PDAC compared to SMCA, the most benign lesion that rarely progresses to invasive carcinoma. It appears that miR-21 up-regulation is an early event in the transformation from normal pancreatic tissue. MiRNA expression has the potential to distinguish PDAC from normal pancreas and BCT. Mechanistically the down-regulation of miR-16, miR-126 and let-7d promotes PDAC transformation by post-transcriptional up-regulation of crucial PDAC oncogenes. We show that miR-126 is able to directly target KRAS; re-expression has the potential as a therapeutic strategy against PDAC and other KRAS-driven cancers

Dendritic calcium signals in rhesus macaque motor cortex drive an optical brain-computer interface

Calcium imaging is a powerful tool for recording from large populations of neurons in vivo. Imaging in rhesus macaque motor cortex can enable the discovery of fundamental principles of motor cortical function and can inform the design of next generation brain-computer interfaces (BCIs). Surface two-photon imaging, however, cannot presently access somatic calcium signals of neurons from all layers of macaque motor cortex due to photon scattering. Here, we demonstrate an implant and imaging system capable of chronic, motion-stabilized two-photon imaging of neuronal calcium signals from macaques engaged in a motor task. By imaging apical dendrites, we achieved optical access to large populations of deep and superficial cortical neurons across dorsal premotor (PMd) and gyral primary motor (M1) cortices. Dendritic signals from individual neurons displayed tuning for different directions of arm movement. Combining several technical advances, we developed an optical BCI (oBCI) driven by these dendritic signalswhich successfully decoded movement direction online. By fusing two-photon functional imaging with CLARITY volumetric imaging, we verified that many imaged dendrites which contributed to oBCI decoding originated from layer 5 output neurons, including a putative Betz cell. This approach establishes new opportunities for studying motor control and designing BCIs via two photon imaging