Social Security: What Would Happen If the Trust Funds Ran Out?

[Excerpt] Each year when the Social Security trustees release their annual report, attention is focused on the projection of the year that the Social Security trust funds will become insolvent. In their 2014 report, the Trustees projected that, under their intermediate assumptions and under current law, the Disability Insurance (DI) trust fund will become exhausted in 2016 and the Old-Age and Survivors Insurance (OASI) trust fund will do so in 2034. Although the two funds are legally separate, they are often described in combination. The trustees project that the combined Social Security trust funds will become exhausted in 2033. Some Americans may believe that if the trust funds were exhausted, Social Security would be unable to pay any benefits. In fact, in 2033, the first year of projected insolvency of the combined Social Security trust funds, the program is projected to have enough tax revenue to pay about 77% of scheduled benefits; that percentage would decline to 72% by the end of the 75-year projection period. Although benefits would be paid in some form, it is unclear how the necessary reductions would be implemented, because the Social Security Act does not specify what would happen to benefits if a trust fund became exhausted. One option would be to pay full benefit checks on a delayed schedule; another would be to make timely but reduced payments. This report explains what the Social Security trust funds are and how they work. It describes the historical operations of the trust funds and the Social Security trustees’ projections of future operations. It explains what could happen if Congress allowed the trust funds to run out. It also analyzes two scenarios that assume Congress waits until the moment of insolvency to act, showing the magnitude of benefit cuts or tax increases needed and how such changes would affect beneficiaries

Beyond EICA : understanding post-establishment evolution requires a broader evaluation of potential selection pressures

Research on post-establishment evolution in nonnative plant populations has focused almost exclusively on testing the Evolution of Increased Competitive Ability (EICA) hypothesis, which posits that the lack of specialized herbivores in the invaded range drives evolution in nonnative plant populations. Fifteen years of conflicting EICA test results suggest that selection pressures other than specialized herbivory are important in driving post-establishment evolution in invasive species. Alternative hypotheses, such as the Evolution of Reduced Competitive Ability (ERCA) hypothesis, have been proposed but have received little attention or testing. We argue that the lack of consensus across studies that test EICA may be due in part to the lack of consistent definitions and varying experimental design parameters, and that future research in this field would benefit from new methodological considerations. We examined previous work evaluating post-establishment evolution and evaluated the range of study systems and design parameters used in testing the EICA hypothesis. Our goal was to identify where different uses of ecological terms and different study parameters have hindered consensus and to suggest a path forward to move beyond EICA in post-establishment evolution studies. We incorporated these methods into a design framework that will increase data harmony across future studies and will facilitate examinations of any potential selection pressure driving evolution in the invaded range

Effect of hypokinesia on cardiac contractile function and nervous regulation of the heart

Longterm hypokinesia caused cardiac deadaptation in rabbits, which resulted in the diminishing of the left ventricular rate of contraction and relaxation, joined later by decreased vascular resistance. As a results, the ejection rate as well as stroke volume and cardiac output were normal. The decrease of the relaxation speed was more obvious at a high heart rate and results in shortening of the diastolic pause and diminishing of cardiac output. Hearts of the hypokinetic animals were characterized by normal maximal pressure developed by a unit of muccardial mass aorta clamping, decreased adrenoreactivity, and increased cholinoreactivity. This complex of changes is contrary to changes observed in adaptation to exercise, but is similar to changes observed in compensatory hypertrophy of the heart

Geographic variation in apparent competition between native and invasive \u3ci\u3ePhragmites australis\u3c/i\u3e

Apparent competition, the negative interaction between species mediated by shared natural enemies, is thought to play an important role in shaping the structure and dynamics of natural communities. However, its importance in driving species invasions, and whether the strength of this indirect interaction varies across the latitudinal range of the invasion, has not been fully explored. We performed replicated field experiments at four sites spanning 900 km along the Atlantic Coast of the United States to assess the presence and strength of apparent competition between sympatric native and invasive lineages of Phragmites australis. Four herbivore guilds were considered: stem‐feeders, leaf‐miners, leaf‐chewers and aphids. We also tested the hypothesis that the strength of this interaction declines with increasing latitude. Within each site, native and invasive plants of P. australis were cross‐transplanted between co‐occurring native and invasive patches in the same marsh habitat and herbivore damage was evaluated at the end of the growing season. Apparent competition was evident for both lineages and involved all but the leaf‐chewer guild. For native plants, total aphids per plant was 296% higher and the incidence of stem‐feeding and leaf‐mining herbivores was 34% and 221% higher, respectively, when transplanted into invasive than native patches. These data suggest that invasive P. australis has a negative effect on native P. australis via apparent competition. Averaged among herbivore types, the indirect effects of the invasive lineage on the native lineage was 57% higher than the reverse situation, suggesting that apparent competition was asymmetric. We also found that the strength of apparent competition acting against the native lineage was comparable to the benefits to the invasive lineage from enemy release (i.e., proportionately lower mean herbivory of the invasive relative to the native taxa). Finally, we found the first evidence that the strength of apparent competition acting against the native lineage (from stem‐feeders only) decreased with increasing latitude. These results suggest that not only could apparent competition be of tantamount importance to enemy release in enhancing the establishment and spread of invasive taxa, but also that these indirect and direct herbivore effects could vary over the invasion range

Biogeography of a Plant Invasion: Plant–Herbivore Interactions

Theory predicts that native plant species should exhibit latitudinal gradients in the strength of their interactions with herbivores. We hypothesize that if an invasive plant species exhibits a different latitudinal gradient in response to herbivores (e.g., a nonparallel gradient), it can create large-scale heterogeneities in community resistance/susceptibility to the invasive species. We conducted a study of latitudinal variation in the strength of herbivory and defenses of native genotypes of Phragmites australis in North America (NA) and Europe (EU) and European invasive genotypes in NA. Within NA, we tested whether (1) invasive genotypes are better defended and suffer less herbivory than co-occurring native genotypes, (2) herbivory and defenses of native P. australis decreases with increasing latitude; and (3) invasive genotypes exhibit either no latitudinal gradient, or a nonparallel latitudinal gradient in herbivory and defenses compared to native genotypes. For the European genotypes, we tested two additional hypotheses: (4) defenses, nutritional condition, and herbivory would differ between the native (EU) and invasive ranges (NA) and (5) latitudinal gradients in defenses and herbivory would be similar between ranges. Within NA, chewing damage, internal stem-feeding incidence, and aphid abundance were 650%, 300%, and 70% lower, respectively, on invasive than native P. australis genotypes. Genotypes in NA also differed in nutritional condition (percent N, C:N ratio), but there was little support for invasive genotypes being better defended than native genotypes. For the European genotypes, herbivory was significantly lower in the invaded than native range, supporting the enemy-release hypothesis. Defense levels (leaf toughness and total phenolics) and tissue percent C and percent N were higher in the invaded than native range for European genotypes. Overall, latitudinal gradients in P. australis nutritional condition, defenses, and herbivory were common. Interestingly, chewing damage and stem-feeder incidence decreased with latitude for native P. australis genotypes in NA and EU, but no latitudinal gradients in response to herbivores were evident for invasive genotypes in NA. Nonparallel latitudinal gradients in herbivory between invasive and native P. australis suggest that the community may be more susceptible to invasion at lower than at higher latitudes. Our study points to the need for invasion biology to include a biogeographic perspective

Parameterized Complexity of the k-anonymity Problem

The problem of publishing personal data without giving up privacy is becoming increasingly important. An interesting formalization that has been recently proposed is the $k$-anonymity. This approach requires that the rows of a table are partitioned in clusters of size at least $k$ and that all the rows in a cluster become the same tuple, after the suppression of some entries. The natural optimization problem, where the goal is to minimize the number of suppressed entries, is known to be APX-hard even when the records values are over a binary alphabet and $k=3$, and when the records have length at most 8 and $k=4$ . In this paper we study how the complexity of the problem is influenced by different parameters. In this paper we follow this direction of research, first showing that the problem is W[1]-hard when parameterized by the size of the solution (and the value $k$). Then we exhibit a fixed parameter algorithm, when the problem is parameterized by the size of the alphabet and the number of columns. Finally, we investigate the computational (and approximation) complexity of the $k$-anonymity problem, when restricting the instance to records having length bounded by 3 and $k=3$. We show that such a restriction is APX-hard.Comment: 22 pages, 2 figure

Biological control of invasive Phragmites australis will be detrimental to native P. australis

Phragmites australis biological control is intended to address a major invasion in North America and is likely to change the ecology of vast areas of coastal and inland wetlands. However, the real risks to the native North American genotypes of P. australis (as indicated by recent research summarized above) may not have been fully considered, particularly the extirpation of native populations or the eventual extinction of the native North American lineage altogether. The concerns we raise need to be considered in the process of developing and approving the release of biological control agents and the entire approval process would benefit from greater transparency and wider input from Phragmites researchers globally

Response to Blossey and Casagrande: ecological and evolutionary processes make host specificity at the subspecies level exceedingly unlikely

We agree with Blossey and Casagrande (2016) that absolute host-specificity is a necessity for successful biological control of invasive plants without unintended consequences for native species. However, inclusion of non-target native species in the diet of a biological control agent is a relatively common phenomenon with native congeners of the target plant species at greatest risk (Pemberton 2000)

Biogeography of a plant invasion: drivers of latitudinal variation in enemy release

© 2016 John Wiley & Sons Ltd Aim: The relationship between herbivory and latitude may differ between native and invasive plant taxa, which can generate biogeographical heterogeneity in the strength of enemy release. Our aim was to compare latitudinal gradients in herbivory between native and invasive plants and investigate whether gradients are driven by local adaptation or phenotypic plasticity. Location: North America. Methods: Using sympatric native and invasive lineages of the wetland grass Phragmites australis and the specialist gall-fly Lipara rufitarsis, we conducted a field survey to examine whether the relationship between herbivory (the proportion of stems galled) and latitude was parallel between lineages. In a subsequent common garden experiment, we assessed whether latitudinal gradients in herbivory were genetically based or driven by phenotypic plasticity. Results: In the field, L. rufitarsis herbivory on the native P. australis lineage increased from 27% of stems galled in southern populations (36.5°) to 37% in northern populations (43.6°), whereas there was no relationship for the invasive lineage. Similar relationships were evident in the common garden experiment, indicating a genetic basis to latitudinal variation in herbivory. Moreover, the invasive lineage suffered five times less herbivory than the native lineage on average, supporting the enemy release hypothesis. However, a genetic basis to this pattern was absent in the common garden experiment, suggesting that local environmental conditions were responsible for the enemy release observed in nature. Specifically, stem height, diameter and density during the L. rufitarsis oviposition period appeared to be important drivers of herbivory. Main conclusions: Non-parallel gradients in herbivory may help explain the equivocal results of other studies that examine enemy release and biotic resistance at local scales, and can be an important mechanism promoting biogeographical variation in invasion success. We suggest that these latitudinal patterns in herbivory and other species interactions are likely to be a common phenomenon across a range of invaded systems