The US current account deficit : how did it come about and what are the policy implications

One of the most remarkable characteristics of the world economy today is the enormous, ever worsening US balance of payments current account deficit, which reached a record level of 5.7 p.c. of GDP in 2004. This has given rise to concerns in academic and political circles regarding the sustainability of the current situation and the potential dangers for the global economy of a sudden, disorderly adjustment. The size of the US current account deficit is not only unprecedented in American post-war history, but it also seems to be exceptional from an international perspective. Moreover, the US deficit contrasts with a surplus in virtually every other region and the problem has consequently taken on a global dimension. The increase in the US current account deficit recorded in the nineties reflects an internal American shortfall in savings. Whereas the private savings-investment equilibrium was restored in 2002 and 2003, the same period saw a huge deficit in the public sector budget. The start of the new millennium brought notable changes in the way the US current account deficit was financed since investments by Asian public authorities in American government debt instruments largely took over the position previously occupied by European private foreign direct investments and investments in equities. It is sometimes put forward that the US, unlike other countries facing similar circumstances, is safeguarded from an attack on its currency because of its prominent role in the international financial system. According to an influential school of thought in economic literature, the current international system can even be seen as a “revived” Bretton Woods system. Indeed, a number of East-Asian countries, including China, use a fixed or quasi-fixed exchange rate against the dollar, which brings to mind an informal dollar standard. Although this set of circumstances has undoubtedly offered various regions in the world a number of mutual benefits during recent years, these exchange rate relations may nevertheless have caused some distortions in US spending, whereas Asian countries have to deal with a growing exchange rate risk on their official reserves. Different scenarios are conceivable to deal with the global imbalances. The results of model simulations show the huge effort required to significantly reduce the US current account deficit which highlights the scale of the problem, emphasising the need for simultaneous economic policy measures in the different economies involved. The concern over global imbalances and the development of exchange rates also feature prominently on the agenda of international forums such as the G7 or G20 meetings. In the statements issued at those meetings, the need for a common approach to tackle the global imbalances is given priority and the belief that excessive exchange rate volatility is not desirable is underlined.current account imbalances, United States current account, financial flows into the United States, international monetary system

Random acyclic networks

Directed acyclic graphs are a fundamental class of networks that includes citation networks, food webs, and family trees, among others. Here we define a random graph model for directed acyclic graphs and give solutions for a number of the model's properties, including connection probabilities and component sizes, as well as a fast algorithm for simulating the model on a computer. We compare the predictions of the model to a real-world network of citations between physics papers and find surprisingly good agreement, suggesting that the structure of the real network may be quite well described by the random graph.Comment: 4 pages, 2 figure

Data assimilation insights on selecting the most valuable atmospheric measurements

We discuss how objective guidance on selecting the most valuable atmospheric measurements on future Mars spacecraft missions can be provided through already developed Martian atmospheric data assimilation systems, and in particular through Observing System Simulation Experiments (OSSEs) which are widely used to design instruments for the Earth’s atmosphere

The optical depth of the Universe to ultrahigh energy cosmic ray scattering in the magnetized large scale structure

This paper provides an analytical description of the transport of ultrahigh energy cosmic rays in an inhomogeneously magnetized intergalactic medium. This latter is modeled as a collection of magnetized scattering centers such as radio cocoons, magnetized galactic winds, clusters or magnetized filaments of large scale structure, with negligible magnetic fields in between. Magnetic deflection is no longer a continuous process, it is rather dominated by scattering events. We study the interaction between high energy cosmic rays and the scattering agents. We then compute the optical depth of the Universe to cosmic ray scattering and discuss the phenomological consequences for various source scenarios. For typical parameters of the scattering centers, the optical depth is greater than unity at 5x10^{19}eV, but the total angular deflection is smaller than unity. One important consequence of this scenario is the possibility that the last scattering center encountered by a cosmic ray be mistaken with the source of this cosmic ray. In particular, we suggest that part of the correlation recently reported by the Pierre Auger Observatory may be affected by such delusion: this experiment may be observing in part the last scattering surface of ultrahigh energy cosmic rays rather than their source population. Since the optical depth falls rapidly with increasing energy, one should probe the arrival directions of the highest energy events beyond 10^{20}eV on an event by event basis to circumvent this effect.Comment: version to appear in PRD; substantial improvements: extended introduction, sections added on angular images and on direction dependent effects with sky maps of optical depth, enlarged discussion of Auger results (conclusions unchanged); 27 pages, 9 figure

Aged garlic extract therapy for sickle cell anemia patients

BACKGROUND: Sickle cell anemia is one of the most prevalent hereditary disorders with prominent morbidity and mortality. With this disorder oxidative, phenomena play a significant role in its pathophysiology. One of the garlic (Allium sativum L.) formulations, aged garlic extract (AGE), has been reported to exert an anti-oxidant effect in vitro, we have evaluated the anti-oxidant effect of AGE on sickle red blood cells (RBC). METHODS: Five patients (two men and three women, mean age 40 ± 15 years, range 24–58 years) with sickle cell anemia participated in the study. AGE was administered at a dose of 5 ml a day. Whole blood samples were obtained at baseline and at 4 weeks for primarily Heinz body analysis. RESULTS: The data were consistent with our hypothesis. In all patients, the number of Heinz bodies decreased over the 4 week period (58.9 ± 20.0% at baseline to 29.8 ± 15.3% at follow-up, p = 0.03). CONCLUSIONS: These data suggest that there is a significant anti-oxidant activity of AGE on sickle RBC. AGE may be further evaluated as a potential therapeutic agent to ameliorate complications of sickle cell anemia

Tailoring teleportation to the quantum alphabet

We introduce a refinement of the standard continuous variable teleportation measurement and displacement strategies. This refinement makes use of prior knowledge about the target state and the partial information carried by the classical channel when entanglement is non-maximal. This gives an improvement in the output quality of the protocol. The strategies we introduce could be used in current continuous variable teleportation experiments.Comment: 16 pages, 6 figures, RevTeX, made changes as recommended by referee, other minor textual corrections, resubmitted to Phys. Rev.

Resonant inelastic x-ray scattering study of charge excitations in La2CuO4

We report a resonant inelastic x-ray scattering study of the dispersion relations of charge transfer excitations in insulating La$_2$CuO$_4$. These data reveal two peaks, both of which show two-dimensional characteristics. The lowest energy excitation has a gap energy of $\sim 2.2$ eV at the zone center, and a dispersion of $\sim 1$ eV. The spectral weight of this mode becomes dramatically smaller around ($\pi$, $\pi$). The second peak shows a smaller dispersion ($\sim 0.5$ eV) with a zone-center energy of $\sim 3.9$ eV. We argue that these are both highly dispersive exciton modes damped by the presence of the electron-hole continuum.Comment: 5 pages, 3 figure

DNA replication stress restricts ribosomal DNA copy number

Ribosomal RNAs (rRNAs) in budding yeast are encoded by ~100–200 repeats of a 9.1kb sequence arranged in tandem on chromosome XII, the ribosomal DNA (rDNA) locus. Copy number of rDNA repeat units in eukaryotic cells is maintained far in excess of the requirement for ribosome biogenesis. Despite the importance of the repeats for both ribosomal and non-ribosomal functions, it is currently not known how “normal” copy number is determined or maintained. To identify essential genes involved in the maintenance of rDNA copy number, we developed a droplet digital PCR based assay to measure rDNA copy number in yeast and used it to screen a yeast conditional temperature-sensitive mutant collection of essential genes. Our screen revealed that low rDNA copy number is associated with compromised DNA replication. Further, subculturing yeast under two separate conditions of DNA replication stress selected for a contraction of the rDNA array independent of the replication fork blocking protein, Fob1. Interestingly, cells with a contracted array grew better than their counterparts with normal copy number under conditions of DNA replication stress. Our data indicate that DNA replication stresses select for a smaller rDNA array. We speculate that this liberates scarce replication factors for use by the rest of the genome, which in turn helps cells complete DNA replication and continue to propagate. Interestingly, tumors from mini chromosome maintenance 2 (MCM2)-deficient mice also show a loss of rDNA repeats. Our data suggest that a reduction in rDNA copy number may indicate a history of DNA replication stress, and that rDNA array size could serve as a diagnostic marker for replication stress. Taken together, these data begin to suggest the selective pressures that combine to yield a “normal” rDNA copy number