Total Factor Productivity and the Mongolian Transition

Total Factor Productivity (TFP)is often used on the macro-economic level as an indicator of changes in efficiency of a country. In many transition economies TFP is seen to have been negative the last decade of the plan economy and starts increasing and become positive after a (quite a) few years of transition. Many authors conclude that this is a gain in efficiency due to the structural changes –such as privatisation and liberalisation – carried out in order to establish a market economy in those countries. In the case of Mongolia, not only non-viable enterprises closed down, but many possibly viable enterprises with potential closed down as well. This raises the question whether changes in TFP were really attributable to increases in efficiency. To investigate this, the mathematical properties of TFP are analysed in order to generate new insights into the development of TFP in Mongolia. Simulations are performed to see what happens with TFP if not the le! ast efficient, but a certain percentage of enterprises in a (closed) economy randomly close down. The robustness of Total Factor Productivity of Mongolia was tested not only for errors in all estimated values but also for measurement errors in the data. It was concluded that in many commonly occurring cases it is not necessary to estimate alpha; that a random closure of enterprises fits the data of Mongolia much more closely than closing only the least efficient enterprises; and that measurement errors in the data influence the estimated TFP significantly

Crack roughness and avalanche precursors in the random fuse model

We analyze the scaling of the crack roughness and of avalanche precursors in the two dimensional random fuse model by numerical simulations, employing large system sizes and extensive sample averaging. We find that the crack roughness exhibits anomalous scaling, as recently observed in experiments. The roughness exponents ($\zeta$, $\zeta_{loc}$) and the global width distributions are found to be universal with respect to the lattice geometry. Failure is preceded by avalanche precursors whose distribution follows a power law up to a cutoff size. While the characteristic avalanche size scales as $s_0 \sim L^D$, with a universal fractal dimension $D$, the distribution exponent $\tau$ differs slightly for triangular and diamond lattices and, in both cases, it is larger than the mean-field (fiber bundle) value $\tau=5/2$

Energy constrained sandpile models

We study two driven dynamical systems with conserved energy. The two automata contain the basic dynamical rules of the Bak, Tang and Wiesenfeld sandpile model. In addition a global constraint on the energy contained in the lattice is imposed. In the limit of an infinitely slow driving of the system, the conserved energy $E$ becomes the only parameter governing the dynamical behavior of the system. Both models show scale free behavior at a critical value $E_c$ of the fixed energy. The scaling with respect to the relevant scaling field points out that the developing of critical correlations is in a different universality class than self-organized critical sandpiles. Despite this difference, the activity (avalanche) probability distributions appear to coincide with the one of the standard self-organized critical sandpile.Comment: 4 pages including 3 figure

Hyperbolicity Measures "Democracy" in Real-World Networks

We analyze the hyperbolicity of real-world networks, a geometric quantity that measures if a space is negatively curved. In our interpretation, a network with small hyperbolicity is "aristocratic", because it contains a small set of vertices involved in many shortest paths, so that few elements "connect" the systems, while a network with large hyperbolicity has a more "democratic" structure with a larger number of crucial elements. We prove mathematically the soundness of this interpretation, and we derive its consequences by analyzing a large dataset of real-world networks. We confirm and improve previous results on hyperbolicity, and we analyze them in the light of our interpretation. Moreover, we study (for the first time in our knowledge) the hyperbolicity of the neighborhood of a given vertex. This allows to define an "influence area" for the vertices in the graph. We show that the influence area of the highest degree vertex is small in what we define "local" networks, like most social or peer-to-peer networks. On the other hand, if the network is built in order to reach a "global" goal, as in metabolic networks or autonomous system networks, the influence area is much larger, and it can contain up to half the vertices in the graph. In conclusion, our newly introduced approach allows to distinguish the topology and the structure of various complex networks

Universality in sandpiles

We perform extensive numerical simulations of different versions of the sandpile model. We find that previous claims about universality classes are unfounded, since the method previously employed to analyze the data suffered a systematic bias. We identify the correct scaling behavior and conclude that sandpiles with stochastic and deterministic toppling rules belong to the same universality class.Comment: 4 pages, 4 ps figures; submitted to Phys. Rev.

Suspended culture of <i>Ostrea edulis</i> in the Calich lagoon (North western Sardinia, Italy): preliminary results

Suspended culture is a widespread farming method used for many bivalve species such as mussels, oysters and scallops. In the Mediterranean, this technique is mainly practised in lagoons or in sheltered coastal areas using floating lines from which molluscs are suspended in several ways. In this study, the European flat oyster (Ostrea edulis Linné, 1758) was grown in suspended lantern nets in the Calich lagoon (Sardinia, Mediterranean Sea) from March 2004 to March 2005. Two distinct groups of 6 lanterns each were hung to longline ropes near the mouth (station 1) and in the central portion of the lagoon (station 2). In each lantern (diameter=50cm; height=30cm), 90 O. edulis specimens were grown and, in order to ensure good water circulation inside the lantern net, fouling organisms were removed every month. Overall mortality, shell length (anterior-posterior axis), shell width (maximum distance on the lateral axis, between both valves of the closed shell) and total wet weight of a 180 specimen oyster sample (30 from each lantern) were recorded every 2 months at each site. In addition, water temperature, salinity, dissolved oxygen, and pH were monitored monthly by means of a multi-parametric probe at both sites (between 10a.m. and 12p.m.). One-way ANOVA was used to test for differences in oyster final mean morphometric characters recorded at the 2 growing stations. Chi-square test (with Yates correction for continuity) was performed to compare survival rates at the end of the trial. From an initial mean shell length of 49.5±4.6mm, O. edulis growth rate showed a similar trend at both the stations. Nevertheless, ANOVA detected significant differences (F=7.10; p&lt;0.01) in final mean oyster length values (83.7±6.5mm at station 1 vs 81.7±7.6mm at station 2). Significant differences (F=9.74; p&lt;0.01) were also found in final mean oyster width (28.4±3.1mm at station 1 vs 27.5±2.8mm at station 2) and weight (F=4.00; p&lt;0.05) values (91.4±16.7g at station 1 vs 87.7±18.3g at station 2). Moreover, chi-square test revealed a significantly different survival rate (χ2=10.04; p&lt;0.01) between the 2 groups (57.4% at station 1 vs 47.6% at station 2).Water temperature, salinity, dissolved oxygen, and pH monthly values recorded at the 2 growing stations were almost identical. Thus, the observed differences in oyster growth and survival seemed not to be due to the hydrological variables considered. Instead, they could probably be related to mechanical and chemical effects of water renewal by coastal waters, which may have led to different seasonal seston food supplies at the 2 sites. The suspended culture of the European flat oyster described in this paper can increase the mollusc production of the Calich lagoon by growing a valuable bivalve species which is naturally scarce in this biotope. In fact, our preliminary results showed good survival and growth rates of O. edulis especially near the mouth of the lagoon. Furthermore, this farming technique could be a possible source of economic benefits for local fishermen and, above all, a low impact aquacultural activity compatible with the environment

Characterization of the casein gene complex in West Africa goats and description of a new αs1-casein polymorphism

The analysis of casein polymorphisms was carried out in West Africa goat populations: Red Sokoto (n = 57), West African Dwarf Nigeria (n = 27), West African Dwarf Cameroon (n = 39), and Borno (n = 37). The 4 casein genes alphas1 (CSN1S1), beta (CSN2), alphas2 (CSN1S2), and kappa (CSN3) were typed at the DNA level. No null alleles were found in any of the genes analyzed. A PCR single-strand conformation polymorphism method was implemented for the identification of CSN1S1*F allele simultaneously with A/01, B/E, N and the new allele. The allele differed from CSN1S1*B by a synonymous transversion TCG->TCT in the codon corresponding to Ser66 of the mature protein. The new allele, named CSN1S1*B', occurred at a high frequency in all the populations, ranging from 0.295 (West African Dwarf Cameroon) to 0.405 (Borno). A greater frequency was found for alleles associated with high alphas1-casein quantity, as has already been observed in the goat populations from the Mediterranean area. The intermediate E allele occurred only in the Red Sokoto and at a low frequency. The faint F allele occurred in 3 populations at frequencies lower than 0.03. Linkage disequilibrium occurred in all the populations, with highly significant differences in Borno, Red Sokoto, and West Africa Dwarf Nigeria, and significant differences in West Africa Dwarf Cameroon. Only 10 haplotypes showed frequencies >= 0.05 in at least 1 of the 4 populations considered, and the overall frequency was >0.1 only for 4 haplotypes: BAAB, B'ACA, ACAB, and BACA (in the order CSN1S1-CSN2-CSN1S2-CSN3). Haplotype BAAB, postulated as an ancestral haplotype in previous studies, was the most common haplotype in all breeds except Borno, where B'ACA was predominant. The results obtained are of considerable significance given that very little information exists on the subject for African goats. The high frequency of strong alleles in the calcium-sensitive caseins as well as the high linkage disequilibrium found among the casein genes in the African breeds analyzed may suggest that specific casein haplotypes have already been selected due to their advantages for nutrition. Haplotypes providing greater protein and casein content would increase the energy content of milk, thus resulting in more favorable growth and survival of young goats and humans consuming the milk

Casein haplotype structure in five Italian goat breeds

The aim of this work was to investigate the genetic structure of the casein gene cluster in 5 Italian goat breeds and to evaluate the haplotype variability within and among populations. A total of 430 goats from Vallesana, Roccaverano, Jonica, Garganica, and Maltese breeds were genotyped at alphas1-casein (CSN1S1), alphas2-casein, (CSN1S2), beta-casein (CSN2), and kappa-casein (CSN3) loci using several genomic techniques and milk protein analysis. Casein haplotype frequencies were estimated for each breed. Principal component analysis was carried out to highlight the relationship among breeds. Allele and haplotype distributions indicated considerable differences among breeds. The haplotype CSN1S1*F- CSN1S2*F-CSN3*D occurred in all breeds with frequencies >0.100 and was the most common haplotype in the Southern breeds. A high frequency of CSN1S1*0-CSN1S2*C-CSN3*A haplotype was found in Vallesana population (0.162). Principal component analysis clearly separated the Northern and Southern breeds by the first component. The variability of the caprine casein loci and variety of resulting haplotypes should be exploited in the future using specific breeding programs aiming to preserve biodiversity and to select goat genetic lines for specific protein production