Large and Small Data Blow-Up Solutions in the Trojan Y Chromosome Model

The Trojan Y Chromosome Strategy (TYC) is an extremely well investigated biological control method for controlling invasive populations with an XX-XY sex determinism. In [35, 36] various dynamical properties of the system are analyzed, including well posedness, boundedness of solutions, and conditions for extinction or recovery. These results are derived under the assumption of positive solutions. In the current manuscript, we show that if the introduction rate of trojan fish is zero, under certain large data assumptions, negative solutions are possible for the male population, which in turn can lead to finite time blow-up in the female and male populations. A comparable result is established for any positive initial condition if the introduction rate of trojan fish is large enough. Similar finite time blow-up results are obtained in a spatial temporal TYC model that includes diffusion. Lastly, we investigate improvements to the TYC modeling construct that may dampen the mechanisms to the blow-up phenomenon or remove the negativity of solutions. The results draw into suspect the reliability of current TYC models under certain situations

Comparative Study of Acetazolamide and Spironolactone on Regional Blood Distribution on Exposure to Acute Hypobaric Hypoxia

Regional blood distribution was studied in rats, which were divided into four groups viz., (i) control, (ii) exposed to acute hypobaric hypoxia, (iii) exposed to acute hypobaric hypoxia after oral treatment with 25mg acetazolamide, and (iv) exposed to acute hypobaric hypoxia after oral treatment with 6mg spironolactone. The regional blood distribution was measured using radio-iodinated serum albumin (R131ISA). The acute hypoxic exposure results in major readjustment in the blood flow to the various organs mainly from the renal and splanchic vascular beds to the heart and brain. Treatment with acetazolamide and spironolactone results only in a slight decrease in blood contents of the heart, brain and lung as compared to thehypoxia alone exposed group

Solid State Physics

Contains reports on five research projects

Lower extremity fatigue increases complexity of postural control during a single-legged stance

<p>Abstract</p> <p>Background</p> <p>Non-linear approaches to assessment of postural control can provide insight that compliment linear approaches. Control entropy (CE) is a recently developed statistical tool from non-linear dynamical systems used to assess the complexity of non-stationary signals. We have previously used CE of high resolution accelerometry in running to show decreased complexity with exhaustive exercise. The purpose of this study was to determine if complexity of postural control decreases following fatiguing exercise using CE.</p> <p>Methods</p> <p>Ten subjects (5 M/5 F; 25 ± 3 yr; 169.4 ± 11.7 cm; 79.0 ± 16.9 kg) consented to participation approved by Western Oregon University IRB and completed two trials separated by 2-7 days. Trials consisted of two single-legged balance tests separated by two Wingate anaerobic tests (WAnT; PreFat/PostFat), or rest period (PreRest/PostRest). Balance tests consisted of a series of five single-legged stances, separated by 30 s rest, performed while standing on the dominant leg for 15-s with the participant crossing the arms over the chest and flexing the non-dominant knee to 90 degrees. High resolution accelerometers (HRA) were fixed superficial to L3/L4 at the approximate center of mass (COM). Triaxial signals from the HRA were streamed in real time at 625 Hz. COM accelerations were recorded in g's for vertical (VT), medial/lateral (ML), and anterior/posterior (AP) axes. A newly developed statistic (R-test) was applied to group response shapes generated by Karhunen Loeve (KL) transform modes resulting from Control Entropy (CE) analysis.</p> <p>Results</p> <p>R-tests showed a significant mean vector difference (<it>p </it>< .05) within conditions, between axes in all cases, except PostFat, indicating the shape of the complexity response was different in these cases. R-test between conditions, within axis, differences were only present in PostFat for AP vs. PreFat (<it>p </it>< .05). T-tests showed a significantly higher overall CE PostFat in VT and ML compared to PreFat and PostRest (<it>p </it>< .0001). PostFat CE was also higher than PostRest in AP (<it>p </it>< .0001).</p> <p>Conclusions</p> <p>These data indicate that fatiguing exercise eliminates the differential complexity response between axes, but increases complexity in all axes compared to the non-fatigued condition. This has implications with regard to the effects of fatigue on strategies of the control system to maintain postural control.</p

Čvrsta disperzija meloksikama: faktorijalno dizajnirani dozirani pripravak za gerijatrijsku populaciju

The objective of the present work was to improve the dissolution properties of the poorly water-soluble drug meloxicam by preparing solid dispersions with hydroxyethylcellulose (HEC), mannitol and polyethylene glycol (PEG) 4000 and to develop a dosage form for geriatric population. Differential scanning calorimetry, X–ray diffractometry, Fourier transform infrared spectroscopy and scanning electron microscopy were used to investigate the solid-state physical structure of the prepared solid dispersions. Higher in vitro dissolution of solid dispersions was recorded compared to their corresponding physical mixtures and the pure drug. PEG 4000 in 1:9 drug to carrier ratio exhibited the highest drug release (100.2%), followed by mannitol (98.2%) and HEC (89.5%) in the same ratio. Meloxicam-PEG 4000 solid dispersion was formulated into suspension and optimization was carried out by 23 factorial design. Formulations containing higher levels of methyl cellulose and higher levels of either sodium citrate or Tween 80 exhibited the highest drug release.Cilj rada bio je poboljšati topljivost meloksikama u vodi pripravom čvrstih disperzija s hidroksietilcelulozom (HEC), manitolom i polietilen glikolom 4000 (PEG 4000) te razviti dozirani pripravaka za gerijatrijsku populaciju. Za ispitivanje fizičke strukture pripravljenih čvrstih disperzija korištene su diferencijalna pretražna kalorimetrija, difraktometrija rentgentskim zrakama, FTIR i pretražna elektronska mikroskopija. Čvrste disperzije su u in vitro uvjetima pokazale bolju topljivost u odnosu na fizičku smjesu i čistu ljekovitu tvar. Najbolje oslobađanje lijeka (100,2%). postignuto je iz disperzija s PEG 4000 (omjer ljekovite tvari i nosača 1:9). Slijede manitol (98,2%) i HEC (89,5%) (isti omjer meloksikama i polimera). Čvrsta disperzija meloksikama s PEG 4000 prevedena je u suspenziju te optimirana 23 faktorijalnim dizajnom. Najbolje oslobađanje ljekovite tvari postignuto je iz pripravaka koji sadrže veći udio etilceluloze i natrijevog citrata, odnosno Tween 80

Miscellaneous Problems

Contains reports on eight research projects