Efficient term size computation for granularity control

Knowing the size of the terms to which program variables are bound at run-time in logic programs is required in a class of optimizations which includes granularity control and recursion elimination. Such size is difficult to even approximate at compile time and is thus generally computed at run-time by using (possibly predeñned) predicates which traverse the terms involved. We propose a technique which has the potential of performing this computation much more efficiently. The technique is based on ñnding program procedures which are called before those in which knowledge regarding term sizes is needed and which traverse the terms whose size is to be determined, and transforming such procedures so that they compute term sizes "on the fly". We present a systematic way of determining whether a given program can be transformed in order to compute a given term size at a given program point without additional term traversal. Also, if several such transformations are possible our approach allows ñnding minimal transformations under certain criteria. We also discuss the advantages and applications of our technique (specifically in the task of granularity control) and present some performance results.

Impaired long-term potentiation induction in dentate gyrus of calretinin-deficient mice

Calretinin (Cr) is a Ca2+ binding protein present in various populations of neurons distributed in the central and peripheral nervous systems. We have generated Cr-deficient (Cr−/−) mice by gene targeting and have investigated the associated phenotype. Cr−/− mice were viable, and a large number of morphological, biochemical, and behavioral parameters were found unaffected. In the normal mouse hippocampus, Cr is expressed in a widely distributed subset of GABAergic interneurons and in hilar mossy cells of the dentate gyrus. Because both types of cells are part of local pathways innervating dentate granule cells and/or pyramidal neurons, we have explored in Cr−/− mice the synaptic transmission between the perforant pathway and granule cells and at the Schaffer commissural input to CA1 pyramidal neurons. Cr−/− mice showed no alteration in basal synaptic transmission, but long-term potentiation (LTP) was impaired in the dentate gyrus. Normal LTP could be restored in the presence of the GABAA receptor antagonist bicuculline, suggesting that in Cr−/− dentate gyrus an excess of γ-aminobutyric acid (GABA) release interferes with LTP induction. Synaptic transmission and LTP were normal in CA1 area, which contains only few Cr-positive GABAergic interneurons. Cr−/− mice performed normally in spatial memory task. These results suggest that expression of Cr contributes to the control of synaptic plasticity in mouse dentate gyrus by indirectly regulating the activity of GABAergic interneurons, and that Cr−/− mice represent a useful tool to understand the role of dentate LTP in learning and memory.

Synergistic interaction between leptin and cholecystokinin to reduce short-term food intake in lean mice

Leptin is a circulating protein involved in the long-term regulation of food intake and body weight. Cholecystokinin (CCK) is released postprandially and elicits satiety signals. We investigated the interaction between leptin and CCK-8 in the short-term regulation of food intake induced by 24-hr fasting in lean mice. Leptin, injected intraperitoneally (i.p.) at low doses (4–120 μg/kg), which did not influence feeding behavior for the first 3 hr postinjection, decreased food intake dose dependently by 47–83% during the first hour when coinjected with a subthreshold dose of CCK. Such an interaction was not observed between leptin and bombesin. The food-reducing effect of leptin injected with CCK was not associated with alterations in gastric emptying or locomotor behavior. Leptin–CCK action was blocked by systemic capsaicin at a dose inducing functional ablation of sensory afferent fibers and by devazepide, a CCK-A receptor antagonist but not by the CCK-B receptor antagonist, L-365,260. The decrease in food intake which occurs 5 hr after i.p. injection of leptin alone was also blunted by devazepide. Coinjection of leptin and CCK enhanced the number of Fos-positive cells in the hypothalamic paraventricular nucleus by 60%, whereas leptin or CCK alone did not modify Fos expression. These results indicate the existence of a functional synergistic interaction between leptin and CCK leading to early suppression of food intake which involves CCK-A receptors and capsaicin-sensitive afferent fibers.

Enhanced tyrosine phosphorylation of the 2B subunit of the N-methyl-D-aspartate receptor in long-term potentiation.

Both serine/threonine and tyrosine phosphorylation of receptor proteins have been implicated in the process of long-term potentiation (LTP), but there has been no direct demonstration of a change in receptor phosphorylation after LTP induction. We show that, after induction of LTP in the dentate gyrus of anesthetized adult rats, there is an increase in the tyrosine phosphorylation of the 2B subunit of the N-methyl-D-aspartate (NMDA) receptor (NR2B), as well as several other unidentified proteins. Tyrosine phosphorylation of NR2B was measured in two ways: binding of antiphosphotyrosine antibodies (PY20) to glycoprotein(s) of 180 kDa (GP180) purified on Con A-Sepharose and binding of anti-NR2B antibodies to tyrosine-phosphorylated proteins purified on PY20-agarose. Three hours after LTP induction, anti-NR2B binding to tyrosine phosphorylated proteins, expressed as a ratio of tetanized to control dentate (Tet/Con), was 2.21 +/- 0.50 and PY20 binding to GP180 was 1.68 +/- 0.16. This increase in the number of tyrosine phosphorylated NR2B subunits occurred without a change in the total number of NR2B subunits. When the induction of LTP was blocked by pretreatment of the animal with the NMDA receptor antagonist MK801, the increase in PY20 binding to GP180 was also blocked (Tet/Con = 1.09 +/- 0.26). The increased PY20 binding to GP180 was also apparent 15 min after LTP induction (Tet/Con = 1.41 +/- 0.16) but not detectable 5 min after LTP induction (Tet/Con = 1.01 +/- 0.19). These results suggest that tyrosine phosphorylation of the NMDA receptor contributes to the maintenance of LTP.

The use of spreading depression waves for acute and long-term monitoring of the penumbra zone of focal ischemic damage in rats.

Slow potential recording was used for long-term monitoring of the penumbra zone surrounding an ischemic region produced by middle cerebral artery (MCA) occlusion in adult hooded rats (n = 32). Four capillary electrodes (El-E4) were chronically implanted at 2-mm intervals from AP -3, L 2 (El) to AP 0, L 5 (E4). Spontaneous or evoked slow potential waves of spreading depression (SD) were recorded during and 4 h after a 1-h MCA occlusion and at 2- to 3-day intervals afterward for 3 weeks. Duration of the initial focal ischemic depolarization was maximal at E4 and decreased with distance from the focus. SD waves in the penumbra zone were high at El and E2, low and prolonged at E3, and almost absent at E4. Amplitude of elicited SD waves was further reduced 3 days later and slowly increased in the following week. Cortical areas displaying marked reduction of SD waves in the first days after MCA occlusion either remained low or showed substantial (60%) recovery, the probability of which decreased with the duration of the initial focal ischemic depolarization and increased with the distance from the focus. It is concluded that the outcome of ischemia monitored by long-term SD recovery in the perifocal region can be partly predicted from the acute signs of MCA occlusion.

Macedonia: Illiberal democracy. CEPS Commentary, 16 May 2014

The recent presidential and early parliamentary elections in Macedonia are only one illustration of the country’s long-term political condition: illiberal democracy. What is needed is a re-think of the instruments and the manner in which major international actors could and should foster constitutional liberalism in Macedonia. While recognising that the primary and essential responsibility lies with Macedonians themselves, the author calls for support to establish the Macedonian state’s capacity for the legitimate exercise of power.

Juncker raises high expectations with ambitious agenda. CEPS Commentary, 16 July 2014

Based on his speech to the European Parliament on July 15th, following his election as President of the European Commission, Jean-Claude Juncker has clearly opted for ‘more Union’ during his five-year term, offering up an ambitious agenda that raises a host of expectations. In this CEPS Commentary, Karel Lannoo outlines the most salient items on Juncker’s agenda, focusing on the most laudable and those that will pose the greatest challenges.

The ‘Unknown Knowns’ of the Global Gas Market. CEPS Essay No. 16, 16 October 2014

Energy markets evolve at least as quickly as the economies they fuel. But development unfolds at an irregular pace, with starts and stops often precipitated by seemingly unpredictable dynamics. Is it really impossible to forecast these ‘revolutions’, if the past can be seen as prologue? The answer might be in the way we look at future events; even if we accept that some events are unpredictable, we may be able to infer much more about the future trends through a broader reading of available data, thus revealing ‘unknown knowns’ that may be useful in understanding paradigm shifts ahead. This paper presents an analysis of the global gas market, offering views on what the most relevant ‘unknown knowns’ of today look like, and hypotheses about some of the possible game-changing events that the market is likely to face in the short to medium term.

The eastern ‘partnership’ of gas. Gazprom and CNPC strike a deal on gas supplies to China. OSW COMMENTARY No. 139, 2014-06-16

The CEOs of Gazprom and China’s CNPC signed a contract concerning Russian gas supplies to China on 21 May 2014 in Shanghai. The contract had been under negotiation for many years and was signed in the presence of the two countries’ presidents. Under this 30-year deal, ultimately 38 billion m3 of natural gas will be exported annually from eastern Siberian fields (Chayandinskoye and Kovyktinskoye) via the Power of Siberia pipeline planned for construction in 2015–2019. The lengthy negotiation process (initial talks regarding this issue began back in the 1990s), the circumstances surrounding the signing of the contract (it was signed only on the second day of Vladimir Putin’s visit to Shanghai, and the Russian president’s personal engagement in the final phase of the talks turned out to be a key element) and information concerning the provisions of the contract (the clause determining the contract price has not been revealed) all indicate that the terms of the compromise are more favourable for China than for Russia. This contract is at present important to Russia mainly for political reasons (it will use the future diversification of gas export routes as an instrument in negotiations with the EU). However, the impact of this instrument seems to be limited since supplies cannot be redirected from Europe to Asia. It is unclear whether the contract will bring the anticipated long-term economic benefits to Gazprom. The gas price is likely to remain at a level of between US$350 and US$390 per 1000 m3. Given the high costs of gas field operation and production and transport infrastructure development, this may mean that supplies will be carried out at the margin of profitability. The Shanghai contract does not conclude the negotiation process since a legally binding agreement on gas pipeline construction has not been signed and not all of the financial aspects of the project have been agreed upon as yet (such as the issue of possible Chinese prepayments for gas supplies).

China on Central-Eastern Europe: ‘16+1’ as seen from Beijing. OSW COMMENTARY NUMBER 166/15.04.2015

From the Introduction. In 2012, China approached the countries of Central-Eastern Europe (CEE) with a proposal concerning regional cooperation in the ‘16+1’ formula. According to Chinese analysts, the rationale behind this breakthrough decision was Beijing’s acknowledgment of the growing importance of the region’s states within the European Union as well as a partial elimination of the ideological differences which had hamstrung cooperation in previous years. It seems that the eurozone crisis may be perceived as the reason for the CEE states’ increased interest in developing their cooperation with China. These circumstances have opened a ‘window of opportunity’ which Beijing has decided to exploit to create a kind of bridgehead in the region which it could later use in its further economic expansion in Europe. Apart from opening the CEE region up for investments, the ‘16+1’ format was intended to facilitate the shaping of relations between China and the EU and to become a tool in building a positive image for China. Chinese experts agree that after three years of functioning, the ‘16+1’ regional cooperation format has helped Beijing achieve its goals only to a limited extent. The major obstacles have included: the immense diversification of the region, barriers related to EU law, insufficient expertise on the part of Chinese companies, the asymmetry of economic needs on both sides, and no willingness within the region itself to develop cooperation. Regardless of the limited effectiveness of activities carried out so far, China has continued its ‘16+1’ initiative. This continuation and the progressing institutionalisation of cooperation in the ‘16+1’ format have often seemed superficial. China has been using this multi-party formula to improve its long-term bilateral relations with selected states in the region and thereby to create a basis for Beijing’s political and economic presence in Central-Eastern Europe.