Manuscript Type: Conceptual Research Question/Issue: Our study evaluates the role of social capital in new director selection, board composition, and board effectiveness. Research Findings/Insights: We take steps toward a theory of director selection, explaining how social capital at the individual-level influences director selection and at the group level influences board effectiveness. At the individual level, social capital is defined as the interpersonal linkages that director candidates have to others, both inside and outside the firm. At the group level, board social capital is an asset that includes both relations of directors and potential resources arising from the relations. Theoretical/Academic Implications: We argue that: 1) social capital can be divided into internal and external dimensions according to its locus and function; 2) both internal and external social capital are associated with board composition through director selection, although the causal logic differs considerably; 3) the influences of social capital on director selection vary according to the context; and 4) both internal social capital and external social capital generate unique resources that are important to board effectiveness. Practitioner/Policy Implications: Our study informs practicing managers, because we describe how and why most research and public discussion has emphasized the role of directors as monitors of managers and this has significantly downplayed the role of directors in providing advice, counsel, and other resources to their organizations. We provide a strong logic for seeking directors with specific types of social capital (internal or external) under specific contexts.

In response to light, water relation parameters (turgor, half-time of water exchange, T 1/2 , and hydraulic conductivity, Lp; T 1=2 }1=Lp) of individual cells of parenchyma sitting in the midrib of leaves of intact corn (Zea mays L.) plants were investigated using a cell pressure probe. Parenchyma cells were used as model cells for the leaf mesophyll, because they are close to photosynthetically active cells at the abaxial surface, and there are stomata at both the adaxial and abaxial sides. Turgor ranged from 0.2 to 1.0 MPa under laboratory light condition (40 lmol m 22 s 21 at the tissue level), and individual cells could be measured for up to 6 h avoiding the variability between cells. In accordance with earlier findings, there was a big variability in T 1/2 s measured ranging from 0.5 s to 100 s, but the action of light on T 1/2 s could nevertheless be worked out for cells having T 1/2 s greater than 2 s. Increasing light intensity ranging from 100 lmol m 22 s 21 to 650 lmol m 22 s 21 decreased T 1/2 by a factor up to five within 10 min and increased Lp (and aquaporin activity) by the same factor. In the presence of light, turgor decreased due to an increase in transpiration, and this tended to compensate or even overcompensated for the effect of light on T 1/2. For example, during prolonged illumination, cell turgor dropped from 0.2 to 1.0 MPa to-0.03 to 0.4 MPa, and this drop caused an increase of T 1/2 and a reduction of cell Lp, i.e. there was an effect of turgor on cell Lp besides that of light. To separate the two effects, cell turgor (water potential) was kept constant while changing light intensity by applying gas pressure to the roots using a pressure chamber. At a light intensity of 160 lmol m 22 s 21 , there was a reduction of T 1/2 by a factor of 2.5 after 10-30 min, when turgor was constant within 60.05 MPa. Overall, the effects of light on T 1/2 (Lp) were overriding those of turgor only when decreases in turgor were less than about 0.2 MPa. Otherwise, turgor became the dominant factor. The results indicate that the hydraulic conductivity increased with increasing light intensity tending to improve the water status of the shoot. However, when transpiration induced by light tends to cause a low turgidity of the tissue, cell Lp was reduced. It is concluded that, when measuring the overall hydraulic conductivity of leaves, both the effects of light and turgor should be considered. Although the mechanism(s) of how light and turgor influence the cell Lp is still missing, it most likely involves the gating of aquaporins by both parameters.

This paper examines the effects of board of directors' network characteristics on firm performance using a sample of 199 large, publicly traded Korean companies from 1990 through 1999. Two board network characteristics are discussed, namely: board network density and board external social capital. Board network density is defined as the extensiveness or the cohesiveness of contact among the members of board of directors, and board external social capital refers to the degree to which board members have outside contacts in the external environment. The test results suggest that a moderate level of board network density enhances firm value, while too cohesive a board network destroys it. It is also found that board members' elite school networks were positively associated with firm performance. Copyright Blackwell Publishing Ltd 2005.

SummaryWhere and how fast does water flow from soil into roots? The answer to this question requires direct and in situ measurement of local flow of water into roots of transpiring plants growing in soil.We used neutron radiography to trace the transport of deuterated water (D 2 O) in lupin (Lupinus albus) roots. Lupins were grown in aluminum containers (30 9 25 9 1 cm) filled with sandy soil. D 2 O was injected in different soil regions and its transport in soil and roots was monitored by neutron radiography. The transport of water into roots was then quantified using a convection-diffusion model of D 2 O transport into roots.The results showed that water uptake was not uniform along roots. Water uptake was higher in the upper soil layers than in the lower ones. Along an individual root, the radial flux was higher in the proximal segments than in the distal segments.In lupins, most of the water uptake occurred in lateral roots. The function of the taproot was to collect water from laterals and transport it to the shoot. This function is ensured by a low radial conductivity and a high axial conductivity. Lupin root architecture seems well designed to take up water from deep soil layers.

Midterm outcomes of PVR in patients with chronic PR were acceptable. PVR should be considered before RV EDVI exceeds 163 ml/m(2) or RV ESVI exceeds 80 ml/m(2), with more attention to RV ESVI.

This study examines the effects of outside directors' proportion and their social capital on firm value using a sample of 473 large, publicly traded Korean companies from 1998 through 2003. Outside director proportion, which is defined as the ratio of outside directors to the total number of directors of a company, is regarded as a proxy of board independence. Outside director social capital, which is defined as the degree to which outside board members have outside contacts in the external environment, is regarded as a proxy of board's ability to extract valuable resources or information from the environment. It is hypothesised that both the proportion of outside directors to the total directors and outside director social capital will be positively associated with firm value. This study reports strong GLS evidence of the relationship between outside director social capital and firm value but no significant relationship between outside director proportion and firm value. Copyright (c) 2007 The Author; Journal compilation (c) 2007 Blackwell Publishing Ltd.

We investigated the catheterization and angiographic findings of 26 patients with Williams' syndrome to evaluate the natural course of supravalvar aortic stenosis and peripheral pulmonary arterial stenosis. The severity of the stenosis was correlated with age and body surface area in terms of the pulmonary arterial index, right ventricular systolic pressure, sinutubular ratio (ratio of measured to mean normal diameter of sinutubular junction), and systolic pressure gradient across the sinutubular junction. In patients with pulmonary arterial stenosis (n=20), right ventricular systolic pressure tended to decrease, and pulmonary arterial index increased, with increase in age and body surface area. Between the groups with and without pulmonary arterial stenosis, there was significant difference in age (mean 4.70 vs. 9.87, p=0.019), body surface area (0.62 vs. 1.16, p=0.002), pulmonary arterial index (152 vs. 317, p=0.002) and right ventricular systolic pressure (73.9 vs. 33.0, p=0.006). As all patients showed similar diameters at the sinutubular junction regardless of age and body size, sinutubular ratio decreased with increases in age and body surface area. The group with abnormal coronary arteries (n=7) had smaller sinutubular ratio (0.46 vs. 0.61, p=0.021) and higher pressure gradients between the left ventricle and the aorta (67.6 vs. 42.2, p=0.023) than did the group with normal coronary arteries. Stenosis of a coronary artery, or a branch of the aortic arch, was observed only in three patients with diffuse aortic stenosis. Our results suggest that, with time, peripheral pulmonary arterial stenosis tends to improve, and supravalvar aortic stenosis to progress. Failure of growth of the sinutubular junction might be responsible for the progression of the aortic lesion. Progression of the aortic lesion may be associated with involvement of the coronary arteries.

Background and Aims Roots have complex anatomical structures, and certain localized cell layers develop suberized apoplastic barriers. The size and tightness of these barriers depend on the growth conditions and on the age of the root. Such complex anatomical structures result in a composite water and solute transport in roots. Methods Development of apoplastic barriers along barley seminal roots was detected using various staining methods, and the suberin amounts in the apical and basal zones were analysed using gas chromatography–mass spectometry (GC-MS). The hydraulic conductivity of roots (Lpr) and of cortical cells (Lpc) was measured using root and cell pressure probes. Key Results When grown in hydroponics, barley roots did not form an exodermis, even at their basal zones. However, they developed an endodermis. Endodermal Casparian bands first appeared as ‘dots’ as early as at 20 mm from the apex, whereas a patchy suberin lamellae appeared at 60 mm. The endodermal suberin accounted for the total suberin of the roots. The absolute amount in the basal zone was significantly higher than in the apical zone, which was inversely proportional to the Lpr. Comparison of Lpr and Lpc suggested that cell to cell pathways dominate for water transport in roots. However, the calculation of Lpr from Lpc showed that at least 26 % of water transport occurs through the apoplast. Roots had different solute permeabilities (Psr) and reflection coefficients (σsr) for the solutes used. The σsr was below unity for the solutes, which have virtually zero permeability for semi-permeable membranes. Conclusions Suberized endodermis significantly reduces Lpr of seminal roots. The water and solute transport across barley roots is composite in nature and they do not behave like ideal osmometers. The composite transport model should be extended by adding components arranged in series (cortex, endodermis) in addition to the currently included components arranged in parallel (apoplastic, cell to cell pathways).