Influence of Intra-cell Traffic on the Output Power of Base Station in GSM

In this paper we analyze the influence of intracell traffic in a GSM cell on the base station output power. It is proved that intracell traffic increases this power. If offered traffic is small, the increase of output power is equal to the part of intracell traffic. When the offered traffic and, as the result, call loss increase, the increase of output power becomes less. The results of calculation are verified by the computer simulation of traffic process in the GSM cell. The calculation and the simulation consider the uniform distribution of mobile users in the cell, but the conclusions are of a general nature

Combining frequency and time domain approaches to systems with multiple spike train input and output

A frequency domain approach and a time domain approach have been combined in an investigation of the behaviour of the primary and secondary endings of an isolated muscle spindle in response to the activity of two static fusimotor axons when the parent muscle is held at a fixed length and when it is subjected to random length changes. The frequency domain analysis has an associated error process which provides a measure of how well the input processes can be used to predict the output processes and is also used to specify how the interactions between the recorded processes contribute to this error. Without assuming stationarity of the input, the time domain approach uses a sequence of probability models of increasing complexity in which the number of input processes to the model is progressively increased. This feature of the time domain approach was used to identify a preferred direction of interaction between the processes underlying the generation of the activity of the primary and secondary endings. In the presence of fusimotor activity and dynamic length changes imposed on the muscle, it was shown that the activity of the primary and secondary endings carried different information about the effects of the inputs imposed on the muscle spindle. The results presented in this work emphasise that the analysis of the behaviour of complex systems benefits from a combination of frequency and time domain methods

Relating reflex gain modulation in posture control to underlying neural network properties using a neuromusculoskeletal model

During posture control, reflexive feedback allows humans to efficiently compensate for unpredictable mechanical disturbances. Although reflexes are involuntary, humans can adapt their reflexive settings to the characteristics of the disturbances. Reflex modulation is commonly studied by determining reflex gains: a set of parameters that quantify the contributions of Ia, Ib and II afferents to mechanical joint behavior. Many mechanisms, like presynaptic inhibition and fusimotor drive, can account for reflex gain modulations. The goal of this study was to investigate the effects of underlying neural and sensory mechanisms on mechanical joint behavior. A neuromusculoskeletal model was built, in which a pair of muscles actuated a limb, while being controlled by a model of 2,298 spiking neurons in six pairs of spinal populations. Identical to experiments, the endpoint of the limb was disturbed with force perturbations. System identification was used to quantify the control behavior with reflex gains. A sensitivity analysis was then performed on the neuromusculoskeletal model, determining the influence of the neural, sensory and synaptic parameters on the joint dynamics. The results showed that the lumped reflex gains positively correlate to their most direct neural substrates: the velocity gain with Ia afferent velocity feedback, the positional gain with muscle stretch over II afferents and the force feedback gain with Ib afferent feedback. However, position feedback and force feedback gains show strong interactions with other neural and sensory properties. These results give important insights in the effects of neural properties on joint dynamics and in the identifiability of reflex gains in experiments

Neural cytoskeleton capabilities for learning and memory

This paper proposes a physical model involving the key structures within the neural cytoskeleton as major players in molecular-level processing of information required for learning and memory storage. In particular, actin filaments and microtubules are macromolecules having highly charged surfaces that enable them to conduct electric signals. The biophysical properties of these filaments relevant to the conduction of ionic current include a condensation of counterions on the filament surface and a nonlinear complex physical structure conducive to the generation of modulated waves. Cytoskeletal filaments are often directly connected with both ionotropic and metabotropic types of membrane-embedded receptors, thereby linking synaptic inputs to intracellular functions. Possible roles for cable-like, conductive filaments in neurons include intracellular information processing, regulating developmental plasticity, and mediating transport. The cytoskeletal proteins form a complex network capable of emergent information processing, and they stand to intervene between inputs to and outputs from neurons. In this manner, the cytoskeletal matrix is proposed to work with neuronal membrane and its intrinsic components (e.g., ion channels, scaffolding proteins, and adaptor proteins), especially at sites of synaptic contacts and spines. An information processing model based on cytoskeletal networks is proposed that may underlie certain types of learning and memory

Sensitivity of contribution margin in milk production on family farms

© 2018, University of Zagreb - Faculty of Agriculture. All rights reserved. Milk production in Serbia is characterized by small surface of production and a large number of small family farms. For rural areas where this production is mostly carried out, economic profitability of production contributes to becoming a family business. This study refers to milk family farms of smaller and medium economic and production capacity, for which the economic analysis in the period of three years was applied and production results were calculated. Applying the calculation method the total revenues and total costs, and contribution margins per cow and per liter of produced milk were computed. By comparing the results obtained on farms A and B, conclusions were drawn, and the sensitivity of contribution margins to change of the given parameters (purchase prices of milk and milk produced per cow) was determined by sensitivity analysis. The stability in production is realized by achieving higher contribution margins with satisfactory milk yield per cow and quality milk, as well acceptable purchase prices of milk

Equipment of family farms with agricultural mechanization in northwest of montenegro

© 2020, University of Montenegro. All rights reserved. The paper presents the results of testing equipment at family farms with agricultural machinery in Northwest Montenegro in municipalities Pljevlja, Žabljak, Kolašin and Mojkovac. In the mentioned municipalities, 123 agricultural farms in 65 villages were surveyed. The total area of available land on farms is 1612.08 ha, of which only 8.27% are cultivated and the rest meadows and pastures. The average area of family farms is 13.11 ha of used agricultural land, which is three times more than the average in Montenegro. Single-axle tractors with an engine power of 5-10 kW are represented by 16% of the total number of tractors. Family farms are not sufficiently equipped with two-axle tractors, because every other one has a tractor (0.51 tractors per farm). The tractors are average power of 30.12 kW. Energy equipments in the surveyed area, expressed through the nominal engine power of two-axle tractors per unit area, in averages at 1.18 kW / ha. There’s a shortage of tractors with engine power over 50 kW with rear and front wheel drive (double traction). Family farms are insufficiently equipped with attached machines (1.28 machines / farm). Ratios per one two-axle tractor are 2.49 attachments and 10.27 ha of used land. There is a lack of machines for vertical tillage and combined machines for pre-sowing soil preparation (chisel plows, seed drills, rotary harrows), as well a seeder for small grains and corn. In addition, there is a lack of machines for the preparation of silage and haylage in silage facilities (self-loading trailers and combines), as well roll presses, wrappers and catchers wrapped in foil

Invasive inflammatory pseudotumor of the pelvis: A case report with review of the literature

Inflammatory pseudotumor (IPT) is a rare benign lesion of unknown etiology, which mimics malignant neoplasm and may arise from various organs. A 53-year-old woman was submitted to diagnostic evaluation because of bilateral, hydroureteronephrosis and oedema of the left leg after a 3-month history of fever of unknown origin. On bimanual vaginal and rectal examination, a mass was involving the uterus, parametria and mostly left adnexa, while the cervix appeared normal. Computed tomographic (CT) scan revealed a 13x10.5 cm mass in the pelvis, mostly at the place of the left adnexa, uterus and both parametria, also involving the surrounding tissues and producing bilateral hydroureteronephrosis. At laparotomy, a grey solid mass was seen, mainly involving the reproductive system. As no radical operation could be performed, the mass was only biopsied and histology showed an inflammatory pseudotumor. Antibiotic therapy was given for one month. Follow-up CT4 and 8 months after laparotomy showed local regression of IPT The last follow-up CT, 20 months after laparotomy, revealed no evidence of tumor. © 2009 Zerbinis Medical Publications