Pilot scale study on retrofitting conventional activated sludge plant for biological nutrient removal.

Eutrophication of receiving waters due to the discharge of nitrogen and phosphorus through the wastewater effluent has received much interest in recent years. Numerous techniques have been proposed and aimed at retrofitting the existing conventional activated sludge process for nutrient removal. A pilot-scale research program was conducted to evaluate the effectiveness of a biological nutrient process for this purpose. The results indicated that creating an anoxic/anaerobic zone before aeration basin significantly enhances total phosphorus (TP) and total nitrogen (TN) removal. Without internal cycle, about 80 percent TP and TN removal were respectively achieved under their optimal conditions. However, adverse trends for phosphorus and nitrogen removal were observed when the ratio of return sludge to the influent was varied in the range between 0.5 and 3.0. The total phosphorus removal decreased as the concentration of BOD5 in the mixture of influent and return sludge decreased. Improved sludge settling properties and reduced foaming problems were also observed during the pilot plant operation. Based upon experimental results, the strategies to modify an existing conventional activated sludge plant into a biological nutrient removal (BNR) system are discussed.

Motion sickness: part I--a theory.

Early reports on space exploration suggested that cosmonauts and astronauts sustained "motion sickness" symptoms described as "dizziness, nausea, vomiting, flashes of light, formed hallucinations or illusions of inversion of image in space." Hallucinations may be due to many causes but most of the above symptoms were similar to those experienced by some patients with expanding intracranial lesions whose symptomatology was referable to the temporoparieto-occipital cortex of the brain. On the basis of our observations, it is suggested that the term "motion sickness" might be applied to earthly symptoms of dizziness, nausea, and vomiting--such as encountered ascending in an elevator or tossing about on the sea--for they are primarily related to the inner ear, the peripheral or end organ. However, when inversion of body image and formed and unformed visual hallucinations are superimposed upon these, there must be interpretation by the temporoparieto-occipital cortex and this might be designed as "motion sickness in space."

Motion sickness: part II--a clinical study based on surgery of cerebral hemisphere lesions.

Man has always been intrigued with the localization of function within the brain but has paid insufficient attention to the long and the short association fiber pathways which, when stimulated, may fire distant areas evoking unusual responses. Three cases of intracerebral lesions are presented to demonstrate the significance of these structures. The vestibular symptoms of dizziness may occur from excitation of the temporal operculum. If, added to this symptom, the patient has spatial disorientation, such as feeling upside down, it suggests that the region of the supramarginal gyrus and the angular gyrus are involved. When unformed visual hallucinations (such as flashes of light) or formed hallucinations (such as distorted images) are present the occipital and midtemporal regions of the brain, respectively, are considered to be the sources of such responses. The symptoms described above were reminiscent of those experienced by some of the cosmonauts and astronauts and it called the authors' attention to this "motion sickness in space." The areas from which such responses may be elicited are the temporoparieto-occipital regions, which are nourished by the posterior cerebral artery and its branches. Vascular insufficiency to this area by spasm of the vessel may be responsible for this symptomatology.

Motion sickness: part III--a clinical study based on surgery of posterior fossa tumors.

Three patients who had large, benign cerebellar tumors were operated upon in the sitting position and developed symptoms referable to the temporoparieto-occipital region of the brain 24-48 h postoperatively. They consisted of dizziness, nausea, vomiting, formed and unformed hallucinations, and inversion of image or disorientation in space, some of which were experienced by some of the astronauts and cosmonauts during space flight. Such findings are not due to stimulation of the cerebellum, the site of the lesion, but must come from the cerebral hemisphere. The symptoms were believed to be caused by "the luxury perfusion" of Lassen with the development of local lactic acidosis secondary to vascular insufficiency to the brain in the distribution of the posterior cerebral artery thus stimulating the temporoparieto-occipital region. This theory is suggested to some degree by the work of Endo et al. using CT scans, which showed the shifting of increased blood flow from the frontal region to the temporoparieto-occipital region following removal of a benign posterior fossa tumor. The mechanism for the compression of the posterior cerebral artery may be due to uncal herniation at the tentorium. The authors believe that it might be well to consider further testing in a vertical or oblique plane rather than only in a centrifugal horizontal one. This method would tend to cause uncal herniation more readily. Monitoring of such effects could be done with the colored CT scan.

Ruptured arteriovenous anomaly in a former woman astronaut candidate.

A case is reported of a former woman astronaut candidate who withstood the rigors of the preliminary physical examinations for this position. Some years later, she sustained a subarachnoid hemorrhage from an arteriovenous malformation in the right parieto-occipital area, which was successfully excised. Postoperatively, she had a marked visual deficit, from which she completely recovered within 3 months. The development of psychomotor seizures 5 months later was due to probable scarring in the right parieto-occipital region of the cerebral cortex, the interpretive area for orientation of body image in space, which had been supplied by the clipped right anterior and posterior cerebral arteries feeding the arteriovenous anomaly. These seizures have been well controlled on anticonvulsants. A lesion in the temporoparieto-occipital region due to a hemorrhage from a ruptured arteriovenous anomaly, resulting in the disabling symptoms of disorientation or loss of body image due to impairment of the interpretive cortex, could be devastating to the pilot and a mission. This case raises the question of an automatic use of the CT brain scan in screening potential space candidates, and even the consideration of a percutaneous femoral four-vessel arteriogram in all, or possibly selected, candidates. Most neurosurgeons and neuroradiologists probably would consider the risks of the latter procedure too great to justify its use for fear of permanent complications to the space candidate.

The functional significance of certain duplicate motor patterns on the cerebral cortex in primates including man.

Rotation elicitable from direct irritation or implantation of the cortical irritant, penicillin, in both rostral and posterior parts of the temporal operculum and on the island cortex in the monkey (Macaca mulatta) has been described and illustrated in photographs. The pathways to and from these temporal and island areas have been considered and the results obtained have been compared with related reports in the literature on rotation in monkeys and man. The probable role of the precentral and postcentral insular areas and their related paths to the contraction of the muscles (sometimes called the agonists) on the side of an extremity in the direction of movement of that extremity and the commensurate relaxation of the muscles (sometimes called the antagonists) cooperating with them on the other side of the extremity is discussed.

Motor effects of stimulation and ablation of the caudate nucleus of the monkey.

Electric stimulation of the caudate nucleus of the lightly anesthetized monkey was undertaken to demonstrate contralateral extremity movement. Contralateral forelimb flexion was observed in 75 percent of stimulations. The caudate nuclei were subsequently ablated, and 40 percent showed abnormal movements, mainly ipsilateral torticollis and ipsilateral eye deviation. The findings are consistent with previous studies using the caudate nucleus of the cat.