Window-Based Channel Impulse Response Prediction for Time-Varying Ultra-Wideband Channels.

This work proposes channel impulse response (CIR) prediction for time-varying ultra-wideband (UWB) channels by exploiting the fast movement of channel taps within delay bins. Considering the sparsity of UWB channels, we introduce a window-based CIR (WB-CIR) to approximate the high temporal resolutions of UWB channels. A recursive least square (RLS) algorithm is adopted to predict the time evolution of the WB-CIR. For predicting the future WB-CIR tap of window wk, three RLS filter coefficients are computed from the observed WB-CIRs of the left wk-1, the current wk and the right wk+1 windows. The filter coefficient with the lowest RLS error is used to predict the future WB-CIR tap. To evaluate our proposed prediction method, UWB CIRs are collected through measurement campaigns in outdoor environments considering line-of-sight (LOS) and non-line-of-sight (NLOS) scenarios. Under similar computational complexity, our proposed method provides an improvement in prediction errors of approximately 80% for LOS and 63% for NLOS scenarios compared with a conventional method.

Statistical Modelling and Characterization of Experimental mm-Wave Indoor Channels for Future 5G Wireless Communication Networks.

This paper presents an experimental characterization of millimeter-wave (mm-wave) channels in the 6.5 GHz, 10.5 GHz, 15 GHz, 19 GHz, 28 GHz and 38 GHz frequency bands in an indoor corridor environment. More than 4,000 power delay profiles were measured across the bands using an omnidirectional transmitter antenna and a highly directional horn receiver antenna for both co- and cross-polarized antenna configurations. This paper develops a new path-loss model to account for the frequency attenuation with distance, which we term the frequency attenuation (FA) path-loss model and introduce a frequency-dependent attenuation factor. The large-scale path loss was characterized based on both new and well-known path-loss models. A general and less complex method is also proposed to estimate the cross-polarization discrimination (XPD) factor of close-in reference distance with the XPD (CIX) and ABG with the XPD (ABGX) path-loss models to avoid the computational complexity of minimum mean square error (MMSE) approach. Moreover, small-scale parameters such as root mean square (RMS) delay spread, mean excess (MN-EX) delay, dispersion factors and maximum excess (MAX-EX) delay parameters were used to characterize the multipath channel dispersion. Multiple statistical distributions for RMS delay spread were also investigated. The results show that our proposed models are simpler and more physically-based than other well-known models. The path-loss exponents for all studied models are smaller than that of the free-space model by values in the range of 0.1 to 1.4 for all measured frequencies. The RMS delay spread values varied between 0.2 ns and 13.8 ns, and the dispersion factor values were less than 1 for all measured frequencies. The exponential and Weibull probability distribution models best fit the RMS delay spread empirical distribution for all of the measured frequencies in all scenarios.

Enabling Remote Health-Caring Utilizing IoT Concept over LTE-Femtocell Networks.

As the enterprise of the "Internet of Things" is rapidly gaining widespread acceptance, sensors are being deployed in an unrestrained manner around the world to make efficient use of this new technological evolution. A recent survey has shown that sensor deployments over the past decade have increased significantly and has predicted an upsurge in the future growth rate. In health-care services, for instance, sensors are used as a key technology to enable Internet of Things oriented health-care monitoring systems. In this paper, we have proposed a two-stage fundamental approach to facilitate the implementation of such a system. In the first stage, sensors promptly gather together the particle measurements of an android application. Then, in the second stage, the collected data are sent over a Femto-LTE network following a new scheduling technique. The proposed scheduling strategy is used to send the data according to the application's priority. The efficiency of the proposed technique is demonstrated by comparing it with that of well-known algorithms, namely, proportional fairness and exponential proportional fairness.

Transplanted sweat glands from mature and aged donors determine cholinergic phenotype and altered density of host sympathetic nerves.

Contact with sweat gland acini causes sympathetic neurons to switch from a catecholaminergic to a cholinergic phenotype during development and following experimental manipulations. Substantial reductions of cholinergic innervation have been shown in the sweat glands of ageing rats and humans. Using in oculo transplantation, we have now studied whether sweat gland target tissues retain the capacity to regulate changes in the phenotype of sympathetic neurons observed in maturity and old age, including a switch from catecholaminergic to cholinergic characters. Markers have been used which indicate changes in nerve fibre morphology (the pan-neuronal marker, PGP9.5) as well as neurotransmitter expression (acetylcholinesterase (AChE), vasocative intestinal polypeptide (VIP) and tyrosine hydroxylase (TH). Sweat glands from young and old donor rats became reinnervated by an organotypic pattern of cholinergic host nerves. Surgical sympathectomy demonstrated that these cholinergic nerve fibres originate from sympathetic neurons of the host superior cervical ganglion (SCG). Retrograde tracing combined with staining for VIP (a marker associated with cholinergic phenotype in neurons supplying sweat glands) showed that SCG neurons projecting to irises with sweat gland implants may be induced to express VIP. We hypothesise that these neurons have been switched from their normal catecholaminergic phenotype to a cholinergic one by contact with the sweat gland implants. Transplants from old donors attracted a density of reinnervation by young host nerves which was appropriate to the age of the donor, thus old sweat glands received a significantly reduced density of innervation compared to young glands. Despite the reduced density of innervation, there was no obvious difference in the ability of young and old implants to induce the switch to a cholinergic phenotype, suggesting that different mechanisms regulate nerve growth and neurotransmitter phenotype.

Effects of facial cooling on elderly and young subjects: interactions with breath-holding and lower body negative pressure.

1. The effects of convective facial cooling by cold air on arterial blood pressure, heart rate and finger blood flow and on the reflex interactions between facial cooling and respiratory and orthostatic cardiac reflexes have been examined in 28 young adults (20-39 years) and 17 elderly (66-78 years) volunteer subjects. 2. During 2 min facial cooling alone, bradycardia was smaller (P < 0.001) and reduction in finger blood flow smaller (P < 0.001) in elderly subjects than in young subjects. Increases in systolic blood pressure and mean arterial pressure were similar and diastolic pressure increased only in the young subjects. Systolic blood pressure and mean arterial pressure remained elevated in the elderly 1 min after facial cooling, but subsided in the young. 3. Arterial blood pressure increased more during a 30-s breath-hold in expiration than in inspiration (P < 0.001) in both groups, and this was exaggerated by breath-hold in expiration combined with facial cooling. The bradycardia produced by facial cooling and breath-holding in expiration was more pronounced in the young subjects than in the elderly (P < 0.002). 4. Interactions between facial cooling and orthostatic reflexes induced by lower-body negative pressure showed significantly different age-related linear trends. Facial cooling diminished the hypotension induced by lower-body negative pressure in both groups. Facial cooling had a greater effect in diminishing the lower-body negative pressure-induced tachycardia in the young than in the elderly. 5. The mechanism of alteration of the facial cooling response in elderly subjects could be largely impairment of arterial baroreflexes, particularly as a result of reduced cardiac vagal activity as well as impairment of cardiopulmonary reflexes with ageing.

Transplanted sweat glands from mature and aged donors determine cholinergic phenotype and altered density of host sympathetic nerves.

Contact with sweat gland acini causes sympathetic neurons to switch from a catecholaminergic to a cholinergic phenotype during development and following experimental manipulations. Substantial reductions of cholinergic innervation have been shown in the sweat glands of ageing rats and humans. Using in oculo transplantation, we have now studied whether sweat gland target tissues retain the capacity to regulate changes in the phenotype of sympathetic neurons observed in maturity and old age, including a switch from catecholaminergic to cholinergic characters. Markers have been used which indicate changes in nerve fibre morphology (the pan-neuronal marker, PGP9.5) as well as neurotransmitter expression (acetylcholinesterase (AChE), vasocative intestinal polypeptide (VIP) and tyrosine hydroxylase (TH)). Sweat glands from young and old donor rats became reinnervated by an organotypic pattern of cholinergic host nerves. Surgical sympathectomy demonstrated that these cholinergic nerve fibres originate from sympathetic neurons of the host superior cervical ganglion (SCG). Retrograde tracing combined with staining for VIP (a marker associated with cholinergic phenotype in neurons supplying sweat glands) showed that SCG neurons projecting to irises with sweat gland implants may be induced to express VIP. We hypothesise that these neurons have been switched from their normal catecholaminergic phenotype to a cholinergic one by contact with the sweat gland implants. Transplants from old donors attracted a density of reinnervation by young host nerves which was appropriate to the age of the donor, thus old sweat glands received a significantly reduced density of innervation compared to young glands. Despite the reduced density of innervation, there was no obvious difference in the ability of young and old implants to induce the switch to a cholinergic phenotype, suggesting that different mechanisms regulate nerve growth and neurotransmitter phenotype.

Circadian body temperatures and the effects of a cold stress in elderly and young subjects.

To determine whether there is a decrement in normal resting body temperature with age, 11 healthy elderly and 11 young adults were studied together for 48 h in warm (21 degrees C) ambient conditions. The resting levels and daytime rhythms of urine and oral temperature were similar, but night-time body temperature fell to a lower value in the young. There were time-of-day effects of increasing skin temperature and metabolic rate in both groups with resting levels higher in the young. After 6 h in cold (6 degrees C) conditions, core (urine) temperature fell by 0.4 degrees C in the elderly subjects but was maintained in the young, and the rise in blood pressure in the elderly exceeded that in the young. Self-reported arousal, however, increased equally in both groups in the cold.

Neurodegeneration in sweat glands and skin of aged rats.

In order to compare age-associated neurodegenerative changes in peripheral nerves of laboratory mammals and humans, we have investigated the density and pattern of different nerve populations innervating sweat glands of ageing rats and compared our results with a previous study of the innervation of human sweat glands. We have also studied age-changes in subepidermal afferent nerves that may be involved in reflex activation of sweat glands. Total nerve density, measured by immunohistochemical staining for the general neuronal marker, protein gene product (PGP9.5) and image analysis, showed a significant decline around secretory coils of sweat glands of old compared to young rats. Marked reductions of acetylcholinesterase (AChE) histochemical staining and of vasoactive intestinal polypeptide (VIP)- and calcitonin gene-related peptide (CGRP)-like immunoreactivity were observed in nerves around sweat glands. In the sub-epidermis, PGP- and CGRP-like immunoreactive nerves were significantly reduced in old rats. The age-related changes in sweat gland innervation of old rats were comparable to those reported in elderly human subjects suggesting that these tissues may provide a suitable model for experimental studies of neuronal ageing.

Immunohistochemical, morphological and functional changes in the peripheral sudomotor neuro-effector system in elderly people.

Age-related changes in the human peripheral sudomotor neuro-effector system have been investigated in six 80-year-olds and six young adults. Histochemical and immunohistochemical studies on forearm skin biopsies showed diminished vasoactive intestinal polypeptide (VIP) and calcitonin gene related peptide (CGRP)-like immunoreactivity and a virtual absence of acetylcholinesterase in the elderly sudomotor nerve endings compared to the young. Reduced size of nerve bundles and decreased density of sympathetic nerve endings adjacent to the sweat glands of old people were shown by the neuronal marker, protein gene product (PGP 9.5), and by electron microscopy. Image analysis techniques were also used to demonstrate a marked regression in secretory coil size with age. Functional decrements accompanying the neurochemical and morphological changes in the neuro-effector system were measured in ten 80-year-olds by local quantitative nicotine axon reflex responses and compared with 12 young adults. These studies demonstrate marked regressive changes in both the nerve endings and target cells in old age and appear to express a significant loss of vigour in trophic interactions.

Oxylog studies of energy expenditure and schistosomiasis in the Sudan.

The effects of varying intensities of S. mansoni infection on physical work performance in agricultural tasks were studied in 269 male farmers living in the highly endemic Gezira area of the Sudan. The subjects were in the age range 18-50 years, and they were subdivided into four infection groups: non-infected (passing no S. mansoni eggs in their faeces), lightly infected (egg excretion 1-499), moderately infected (egg excretion 500-999), and heavily infected (egg excretion 1000+ eggs g-1 faeces). The Oxylog, a portable oxygen analyser, was used to measure energy expenditure throughout the field studies. The investigations showed that heavy S. mansoni infection significantly lowered oxygen intake by 20-30% during agricultural work tasks. There was a clear relationship between the intensity of S. mansoni infection and both the aerobic power output and morbidity in those populations. Anti-schistosomal treatment (praziquantel) given over a period of 1 year produced a marked improvement in working capacity and reduced morbidity.

Studies of contents of norepinephrine and 5-hydroxytryptamine in brain--I. Normal and cold exposure.

The levels of NE and 5-HT were determined in different brain regions of the field rat and the guinea-pig under normal conditions and following cold exposure at 10 degrees C. Under normal conditions NE was found to be mainly accumulated in the midbrain while 5-HT exhibited its highest value in the pons plus medulla of both animals. Cold exposure of the field rat caused a general increase in NE concentrations while a general decrease occurred in the brain regions of the guinea-pig. 5-HT mostly decreased in the two animals. These changes in the amine levels could be related directly to the animal's response to cold.

Studies of contents of norepinephrine and 5-hydroxytryptamine in brain--II. Effect of sodium barbitone and chlorpromazine.

The effect of i.p. injection of sodium barbitone and chlorpromazine (25 mg/100 g body wt) on the levels of NE, 5-HT and body temperature was investigated in the brain regions of the field rat and the guinea-pig. Injection of the field rat with barbitone sodium or chlorpromazine provoked a general increase in the NE and 5-HT concentrations of the various brain parts. In guinea-pig variable changes were observed. Following injection with either of the two drugs, hypothermia was induced in the two animals at all of the time intervals examined.

Effect of heat stress on brain 5-hydroxytryptamine and 5-hydroxyindoleacetic acid in some vertebrate species.

1. The variations in 5-HT and 5-HIAA levels following heat exposure and split heat doses were determined in the different brain regions of Gerbillus pyramidum, Streptopelia senegalensis aegyptiaca and Agama stellio. 2. Heat exposure was found to be associated with an increase in the levels of the two indole compounds. 3. The 5-HT concentrations increased markedly in the three species following the first heat dose and decreased following the second dose in the various brain regions except in the cerebellum of Agama. 4. The increased 5-HT levels when animals are exposed to high temperature probably represent a response to activate heat-loss mechanisms and to depress heat production.

Effect of cold exposure on brain 5-hydroxytryptamine and 5-hydroxyindoleacetic acid in some vertebrate species.

1. The changes in 5-HT and 5-HIAA levels were studied in the brain regions of Gerbillus pyramidum, Streptopelia senegalensis aegyptiaca and Agama stellio following exposure to cold. 2. In general, the 5-HT levels increased in the Gerbillus brain parts and decreased in those of Streptopelia. 3. Cold exposure in the Agama brain regions caused a transient decrease in the 5-HT levels of the cerebral hemispheres, midbrain and pons plus medulla after 6 hr and a general increase after 12, 24 and 48 hr. 4. It is concluded that cold exposure may be associated with increased activity of 5-HT ergic neurons and the rate of turnover of 5-HT to 5-HIAA.