Autonomous control for miniaturized mobile robots in unknown pipe networks.

Despite recent advances in robotic technology, sewer pipe inspection is still limited to conventional approaches that use cable-tethered robots. Such commercially available tethered robots lack autonomy, and their operation must be manually controlled via their tethered cables. Consequently, they can only travel to a certain distance in pipe, cannot access small-diameter pipes, and their deployment incurs high costs for highly skilled operators. In this paper, we introduce a miniaturised mobile robot for pipe inspection. We present an autonomous control strategy for this robot that is effective, stable, and requires only low-computational resources. The robots used here can access pipes as small as 75 mm in diameter. Due to their small size, low carrying capacity, and limited battery supply, our robots can only carry simple sensors, a small processor, and miniature wheel-legs for locomotion. Yet, our control method is able to compensate for these limitations. We demonstrate fully autonomous robot mobility in a sewer pipe network, without any visual aid or power-hungry image processing. The control algorithm allows the robot to correctly recognise each local network configuration, and to make appropriate decisions accordingly. The control strategy was tested using the physical micro robot in a laboratory pipe network. In both simulation and experiment, the robot autonomously and exhaustively explored an unknown pipe network without missing any pipe section while avoiding obstacles. This is a significant advance towards fully autonomous inspection robot systems for sewer pipe networks.

Effect of intensive insulin therapy on progression of overt nephropathy in patients with type 1 diabetes mellitus.

OBJECTIVE: To assess the effects of chronic (long-term) intermittent intravenous insulin therapy (CIIIT) on the progression of overt nephropathy in patients with type 1 diabetes mellitus. METHODS: We undertook a retrospective longitudinal three-center study of 31 patients with type 1 diabetes mellitus and overt nephropathy, who were receiving intensive subcutaneous insulin therapy (four insulin injections daily) and weekly CIIIT. All study patients had follow-up consultations weekly for at least 12 months (mean duration, 37.0 +/- 4.6 months). Each patient had monthly hemoglobin A(1c) (by high-performance liquid chromatography) and semiannual creatinine clearance determinations. RESULTS: The hemoglobin A(1c) levels declined significantly from 8.6 +/- 0.6% to 7.6 +/- 0.3% (P = 0.0062) during the study period. The creatinine clearance remained essentially unchanged (from 46.1 +/- 3.0 mL/min per 1.73 m 2 at baseline to 46.0 +/- 3.9 mL/min per 1.73 m 2 at the end of the observation period, with an average annualized slope increase of 3.39 +/- 1.5 mL/min per year--no significant difference). CONCLUSION: The addition of CIIIT to intensive subcutaneous insulin therapy in patients with type 1 diabetes mellitus seems to arrest or appreciably reduce the progression of overt diabetic nephropathy, as well as substantially improve their glycemic control.

Anterior pitutiary and pitutiary-dependent target organ function in men infected with the human immunodeficiency virus.

To evaluate pituitary and pituitary-dependent target organ function in men infected with the human immunodeficiency virus (HIV), 26 ambulatory HIV-positive men (13 with acquired immunodeficiency syndrome [AIDS]) and nine healthy control men were administered rapid sequential injections of thyrotropin (TSH)-releasing hormone (TRH), gonadotropin-releasing hormone (GnRH), ovine corticotropin (ACTH)-releasing hormone (oCRH), and human growth hormone-(GH)-releasing hormone (hGHRH). Blood samples were collected before and for 90 minutes after the injections for immunoassay of pituitary hormones, cortisol, testosterone, and free thyroxine (fT(4)). Data were analyzed for each group of men considering basal, peak, and incremental responses to the releasing hormones, as well as the time course of response of each hormone. Mean basal serum GH concentrations were the same in all groups (control, AIDS, and non-AIDS HIV-positive), but stimulated GH levels were substantially higher at all time points in both groups of HIV-positive subjects. Results for prolactin (PRL) were similar, although stimulated PRL levels were increased significantly only in the AIDS group. The mean basal serum TSH concentration and stimulated TSH levels at 60 and 90 minutes were significantly greater in the AIDS group than in the control group. Basal mean fT(4) concentration in the AIDS group was significantly less than in the control group. Mean basal and stimulated serum (total) testosterone concentrations in all groups were the same. However, basal serum luteinizing hormone (LH) concentrations in both groups of HIV-infected men were significantly greater than in controls; stimulated (peak) LH levels were not different from control levels. Basal and peak stimulated plasma ACTH concentrations were significantly increased in both HIV-infected groups. Basal serum cortisol levels were also greater, on average, in HIV-infected groups, although stimulated (peak) cortisol responses were not different. These results indicate that basal serum concentrations of TSH, LH, ACTH, and cortisol are modestly increased in men with AIDS, and that maximum levels of GH, PRL, TSH, and ACTH stimulated by the releasing hormones are also increased in this group. Measurements obtained in the non-AIDS HIV-infected men showed a pattern generally similar to that obtained in men with AIDS, but less marked. The basis for the increased pituitary activity is unknown; we speculate that it is due to modestly impaired target organ function and to increased hypothalamic stimulation.

Long-term intermittent intravenous insulin therapy and type 1 diabetes mellitus.

An important defect in insulin-dependent diabetes mellitus (IDDM) is that the liver does not meet its full fuel-processing function, because many of the enzymes involved depend on high insulin concentrations in the portal vein. We tried to reactivate the liver by long-term treatment of IDDM patients with intravenous insulin in pulses, with the aim of achieving high portal-vein concentrations during and after a glucose meal. We studied 20 IDDM patients with brittle disease; despite use of a four-injection regimen with manipulation of insulin doses, diet, and physical activity, and frequent clinic visits for at least a year, these patients still had wide swings in blood glucose and frequent hypoglycaemic reactions. The intermittent therapy consisted of 7-10 pulses of intravenous insulin, infused while the patient was ingesting carbohydrate, primarily glucose, during the first hour of a 3 h treatment; three treatments were given in a day. After 2 consecutive days' treatment, patients were treated for 1 day per week. No patient was withdrawn from the study. At the time of this analysis the duration of intermittent treatment ranged from 7 to 71 months (mean 41 [SE 5] months). Haemoglobin A1C concentrations declined from 8.5 (0.4)% at the end of the stabilisation phase to 7.0 (0.2)% at the analysis point (p = 0.0003). During the same time the frequencies of major and minor hypoglycaemic events also fell significantly (major 3.0 [1.1] to 0.1 [0], minor 13.0 [2.6] to 2.4 [0.8] per month; both p < 0.0001). Because the use of saline rather than insulin pulses would have led to unacceptable hyperglycaemia we opted for a historical control design. The absence of a true control group limits the interpretation of these preliminary results, but we believe further studies of hepatic and muscle metabolism before and after long-term intermittent intravenous insulin therapy would be worth while.