Credit Cycles in a OLG Economy with Money and Bequest

In this paper we develop an extended version of the original Kiyotaki and Moore's model ("Credit Cycles" Journal of Political Economy, vol. 105, no 2, April 1997)(hereafter KM) using an overlapping generation structure instead of the assumption of infinitely lived agents adopted by the authors. In each period the population consists of two classes of heterogeneous interacting agents, in particular: a financially constrained young agent (young farmer), a financially constrained old agent (old farmer), an unconstrained young agent (young gatherer), an unconstrained old agent (old gatherer). By assumption each young agent is endowed with one unit of labour. Heterogeneity is introduced in the model by assuming that each class of agents use different technologies to pro- duce the same non durable good. If we study the effect of a technological shock it is possible to demonstrate that its effects are persistent over time in fact the mechanism that it induces is the reallocation the durable asset ("land")among agents. As in KM we develop a dynamic model in which the durable asset is not only an input for production processes but also collateralizable wealth to secure lenders from the risk of borrowers'default. In a context of intergenerational altruism, old agents leave a bequest to their offspring. Money is a means of payment and a reserve of value because it enables to access consumption in old age. For simplicity we assume that preferences are defined over consumption and bequest of the agent when old. Money plays two different and contrasting roles with respect to landholding. On the one hand, given the bequest, the higher the amount of money the young wants to hold, the lower landholding. On the other hand the higher the money of the old, the higher the resources available to him and the higher bequest and landholding. We study the complex dynamics of the allocation of land to farmers and gatherers - which determines aggregate output - and of the price of the durable asset. If a policy move does not change the ratio of money of the farmer and of the gatherer, i.e. if the central bank changes the rates of growth of the two monetary aggregates by the same amount, monetary policy is superneutral, i.e. the allocation of land to the farmer and to the gatherer does not change, real variables are unaffected and the only e¤ect of the policy move is an increase in the rate of inflation, which is pinned down to the (uniform) rate of change of money, and of the nominal interest rate. If, on the other hand, the move is differentiated, i.e. the central bank changes the rates of growth of the two monetary aggregates by different amounts so that the rates of growth are heterogeneous, money is not superneutral, i.e. the allocation of land changes and real variables are permanently affected, even if the rates of growth of the two aggregates go back to the original value afterwardsCredit Cycles, monetary policy

Daily rhythm of circulating fat soluble vitamin concentration (A, D, E and K) in the horse

BACKGROUND: Many physiological processes of mammalian species exhibit daily rhythmicity. An intrinsic relationship exists between fat soluble vitamins (A, D, E and K) and several body functions. Few investigations on the rhythmic pattern of vitamins in domestic animals have been carried out. The present study evaluated the circadian rhythmicity of fat soluble vitamins in the horse. METHODS: Blood samples from 5 Thoroughbred mares were collected at four-hour intervals over a 48-hour period (starting at 8:00 hours on day 1 and finishing at 4:00 on day 2) via an intravenous cannula inserted into the jugular vein. Fat soluble vitamin concentration in the serum (A, D, E and K) was measured by HPLC. One-way repeated measures analysis of variance (ANOVA) was used to determine significant differences. p values < 0.05 were considered statistically significant. RESULTS: ANOVA showed a highly significant effect of time in all the horses for the vitamins studied (p < 0.0001). The application of the periodic model and the statistical analysis of the "Cosinor" enabled us to define the periodic parameters and their acrophases (expressed in hours) during the 2 days of monitoring: all the studied vitamins showed diurnal acrophases with values between 15:16 and 18:08 hours. CONCLUSION: Fat soluble vitamins exhibit daily rhythmicity with diurnal peak. Further investigations could help optimize the use of these substances according to their circadian (or other) rhythms

Borrowing constraints and complex dynamics in an OLG framework

In this paper we model an OLG economy à la Kiyotaki and Moore whose novel feature is the role of money as a store of value and of bequest as a source of funds to be "invested" in landholding. The dynamics generated by the model are generally characterized by irregular cyclical trajectories and, under special con.guration of the parameters, a strange attractor appears. In this setting, an expansionary monetary policy may have a stabilizing role due to the interaction between money holding and the accumulation of borrowers' net worth

Thirty-day rhythmicity in electrocardiographic and electrolytic parameters in the athletic horse

This paper describes circatrigintan progress of some electrocardiographic parameters and of the serum electrolytes in the jumper horse during a period of pre-competitive training performed in order to define the temporal organization of some parameters employed to evaluate the athletic performance of the horse. Five Sella Italiana horses, clinically healthy and specifically trained have been utilized for the study. All the subjects have undergone electrocardiographic recordings and blood sample takings by means of jugular venopuncture, at rest and always at the same hour, every five days for a period of one month. The following electrocardiographic parameters have been measured on individual ECG-recordings: P wave duration and amplitude, P-Q interval duration, QRS complex duration, R wave amplitude, T wave duration, S-T segment duration, Q-T interval duration, the longest and shortest R-R intervals; besides, mean R-R interval and D R-R, the highest, lowest and mean heart rate, have been calculated. The concentrations of magnesium, calcium, phosphorus and chlorine and of sodium and potassium have been determined on the blood samples, respectively by UV spectrophotometry and by flaming. The application of a statistic trigonometric model has permitted to point out the circatrigintan periodicity of the following electrocardiographic parameters: P wave duration, T wave duration, R wave amplitude, mean R-R interval and mean heart rate, and of the following serum electrolytes: sodium and magnesium. Based on these results, it is hypothesized that the cardiovascular system follows a “deterministic” progress with a “linear” variability systematically predictable within the temporal period considered

Central fatigue and nycthemeral change of serum tryptophan and serotonin in the athletic horse

BACKGROUND: The serotonergic system is associated with numerous brain functions, including the resetting of the mammalian circadian clock. The synthesis and metabolism of 5-HT in the brain increases in response to exercise and is correlated with high levels of blood-borne tryptophan (TRP). The present investigation was aimed at testing the existence of a daily rhythm of TRP and 5-HT in the blood of athletic horses. METHODS: Blood samples from 5 Thoroughbred mares were collected at 4-hour intervals for 48 hours (starting at 08:00 hours on day 1 and finishing at 4:00 on day 2) via an intravenous cannula inserted into the jugular vein. Tryptophan and serotonin concentrations were assessed by HPLC. Data analysis was conducted by one-way repeated measures analysis of variance (ANOVA) and by the single cosinor method. RESULTS: ANOVA showed a highly significant influence of time both on tryptophan and on serotonin, in all horses, on either day, with p values < 0.0001. Cosinor analysis identified the periodic parameters and their acrophases (expressed in hours) during the 2 days of monitoring. Both parameters studied showed evening acrophases. CONCLUSION: The results showed that serotonin and tryptophan blood levels undergo nycthemeral variation with typical evening acrophases. These results enhance the understanding of the athlete horse's chronoperformance and facilitate the establishment of training programs that take into account the nycthemeral pattern of aminoacids deeply involved in the onset of central fatigue

Serum iron, ferritin, transferrin and haptoglobin concentration variations during repeated show jumping competition in horse

Modifications of the iron profile in athlete horses during two international three star (***) show jumping competitions performed in two consecutive weekends were evaluated. Serum iron, ferritin, transferrin, and haptoglobin were assessed in 12 well-trained Italian Saddle horses. Blood samplings were performed before the first day of competition (R1), within 10 min from the end of each competition (J1, J2) and on the day after competition (R2). The same plan was followed during the second weekend (J3, J4 and R3). One-way repeated measures analysis of variance (ANOVA) was applied on obtained data, and a significant effect of exercise (P < 0.05) on all studied indices was found. These results suggest that serum iron, transferrin, ferritin and haptoglobin are responsive to intense exercise and could be considered important indicators that may give important information about the horse's performance

Godišnje promjene nekih pokazatelja mijene tvari u mliječnih krava na području Sredozemlja.

The seasonal rhythms reflect the ability of the endogenous adaptive mechanism to react in advance to the regular environmental changes associated with the seasons. It seems that these biochemical parameters are often influenced by a change in physiological status. The aim of this study was to assess the trend of annual variations of some biochemical parameters in dairy cows. The experimental subjects were ten dairy cows and the start of the experimental period coincided with the last month of pregnancy. These animals were monitored for one year and blood samples were collected every month. From the obtained sera, total bilirubin, blood urea nitrogen (BUN), creatinine, total cholesterol, non-esterified fatty acids (NEFA), tryglicerides, β-hydroxybutyrate, total proteins, calcium and phosphorus were assessed by means of an automated spectrophotometer. All the results were expressed as mean ± standard deviation (SD). Data were normally distributed (P<0.05, Kolmogorov-Smirnov test). One method of repeated measurement, the Analysis of Variance (ANOVA), was applied to determine the effect of time during the experimental period (12 months) and P values of <0.05 were considered statistically significant. Using cosinor-rhythmometry, three rhythmic parameters were determined: mesor (mean level), amplitude (half the range of oscillation) and acrophase (Φ, time of peak). A significant effect of time (P<0.0001) was shown for all the parameters, except for NEFA. After application of cosinor rhythmometry, only total bilirubin, creatinine, triglycerides and β-hydroxybutyrate showed a seasonal rhythm. In conclusion we can affirm that our results supplement the current information available about the circannual changes in the metabolic activity of these animals and help us to evaluate the adaptation of these animals to environmental changes, together with the metabolic effect of calving and lactation.Ritam promjene godišnjih doba utječe na endogeni adaptacijski mehanizam kako bi on unaprijed reagirao na sezonske promjene u okolišu. Čini se da promjene u fiziološkom stanju često utječu na biokemijske pokazatelje vezane uz taj mehanizam. Svrha je ovog istraživanja procijeniti utjecaj godišnjih promjena na neke biokemijske pokazatelje u mliječnih krava. U pokus je bilo uzeto 10 mliječnih krava, a sam je pokus započeo kad su one bile u posljednjem mjesecu bređosti. Krave su bile promatrane tijekom jedne godine, a krv im je bila uzimana svaki mjesec. Uzeti uzorci seruma bili su automatskim spekrofotometrom pretraženi na ukupni bilirubin, dušik iz ureje u krvi (BUN), kreatinin, ukupni kolesterol, neesterificirane masne kiseline, trigliceride, β-hidroksibutirat, ukupne bjelančevine te kalcij i fosfor. Rezultati su bili izraženi kao srednja vrijednost ± standardna devijacija (SD). Podatci su bili normalno distribuirani (P<0,05, Kolmogorov-Smirnov test). Za ponovljeno mjerenje bila je primijenjena analiza varijance (ANOVA) kako bi se odredio učinak vremena tijekom pokusnog razdoblja (12 mjeseci) te su P vrijednosti <0,05 smatrane statistički značajnima. Uporabom Cosinor ritmometrije određena su četiri ritmička pokazatelja: mesor (srednja vrijednost), amplituda (polovica područja oscilacije) i akrofaza (Φ, vršno vrijeme). Značajan učinak vremena (P<0,0001) dokazan je za sve pokazatelje, osim za neesterificirane masne kiseline. Nakon primjene cosinor ritmometrije samo su ukupni bilirubin, kreatinin, trigliceridi i β-hidroksibutirat pokazivali sezonski ritam. Zaključno se može potvrditi da rezulati predstavljaju doprinos aktualnim informacijama o godišnjim promjenama metaboličke aktivnosti u krava i pomažu vrednovanju njihove prilagodbe okolišnim promjenama kod teljenja i laktacije

Oksidativni stres u punokrvnjaka u tijeku službenih utrka na 1800 metara.

The aim of the present study was to find possible relationships between physical exercise and oxidative stress in thoroughbreds during official races. For this purpose six healthy and trained thoroughbreds were used. Blood samples were collected from all horses at rest, immediately after the race, and 30 and 180 min after the race. The following parameters were assessed on obtained serum using the spectrophotometer method: lactate dehydrogenase, creatine kinase, reactive oxygen species, thiol antioxidant barrier and antioxidant barrier. Obtained results showed the highly significant effect of exercise on some of the studied parameters: LDH, F(3,15) = 49.85, P<0.0001; ROMs, F(3,15) = 60.71, P<0.0001; Oxy-adsorbent, F(3,15) = 393.70, P<0.0001. No statistical significant differences were observed for CK and SHP. Our results appear to indicate that during official races thoroughbreds generate free radicals, but are unable to determine a significant lyses of skeletal muscle cellsCilj istraživanja bio je ustanoviti moguću povezanost između tjelesne vježbe i oksidativnog stresa u punokrvnjaka u tijeku službenih utrka. Istraživanje je provedeno na osam zdravih uvježbanih punokrvnjaka. Svima su uzeti uzorci krvi u tijeku odmora, netom nakon utrke te 30 i 180 minuta nakon toga. Spekrofotometrijom su određivani sljedeći pokazatelji u uzorcima seruma: laktat dehidrogenaza, kreatin kinaza, vrsta reaktivnog kisika, tiol-antioksidativna barijera i antioksidativna barijera. Rezultati su pokazali znatan učinak vježbe na neke istraživane pokazatelje: LDH, F (3,15) = 49,85, P<0,0001; ROMs, F (3,15) = 60,71, P<0,0001; oksiadsorbens, F (3,15) = 393,70, P<0,0001. Nisu ustanovljene statistički značajne razlike za kreatin-kinazu i tiolantioksidativnu barijeru. Rezultati pokazuju da se u punokrvnjaka u tijeku službenih utrka oslobađaju slobodni radikali, ali se ne nije mogla utvrditi značajna liza stanica kosturnoga mišićja