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This investigation resulted from a pilot research paper prepared in conjunction with a graduate course on the Civil War. This study suggested that the Federal blockade of the Confederacy may not have contributed significantly to its defeat. Traditionally, historians had assumed that the Union's Anaconda Plan had effectively strangled the Confederacy. Recent studies which compared the statistics of ships captured to successful infractions of the blockade had somewhat revised these views. While accepting these revisionist findings as broadly valid, this investigation strove to determine specifically the effectiveness of Admiral Farragut's West Gulf Blockading Squadron. Since the British Foreign Office maintained consulates in three blockaded southern ports and in many Caribbean ports through which blockade running was conducted, these consular records were vital for this study. Personal research in Great Britain's Public Record Office disclosed valuable consular reports pertaining to the effectiveness of the Federal blockade. American consular records, found in the National Archives in Washington, D.C. provided excellent comparative reports from those same Gulf ports. Official Confederate reports, contained in the National Archives, various state archives and in the published Official Records of the Union and Confederate Armies revealed valuable statistical data on foreign imports. Limited use was made of Spanish and French consular records written from ports involved in blockade running. Extensive use was made of Senate and House documents in determining Federal blockade policy during the war. The record of the Navy's enforcement of the blockade was found in The Official Records of the Union and Confederate Navies. The contemporary reports of Union and Confederate governmental officials was found in James D. Richardson's respective works on The Messages and Papers, and in the published diaries of Gideon Welles and Gustavas Fox. Contemporary newspapers and first hand accounts by participants on both sides provided color and perspective. In evaluating the performance of the West Gulf Blockading Squadron, a review of the international laws governing blockading was undertaken, emphasizing America's traditional posture regarding the blockades of other nations. Under Gideon Welles, the Federal navy became a powerful and efficient force, although the navy's enforcement of the blockade often resulted in serious diplomatic embarrassment, especially from maritime incidents occurring near the mouth of the Rio Grande River. Nearby Matamoros, Mexico virtually became an international trade mart for Confederate cotton and imports. However, much contraband trade was conducted through blockaded Gulf ports such as Galveston, Texas. It is concluded that the West Gulf Blockading Squadron performed only satisfactorily at best. This did not result so much from innate limitations as from outside factors. Among the latter were the open door at Matamoros, the Lincoln administration's diplomatic timerity and national policies that authorized a type of cotton trade with the south. Further, the better vessels were assigned land campaign priorities. The statistics of the cotton trade in this portion of the Confederacy show that cotton exports were significantly high. Most of these exports egressed via Matamoros, but a high percentage existed through blockaded Gulf ports. The fact that 10,000 bales of cotton left the heavily guarded port of Galveston in the last six months of the war indicates the inefficiency of the West Gulf Blockade. It appears that the West Gulf Blockade was effective enough to create scarcity but never effective enough to seriously interdict the flow of trade. That the Trans-Mississippi Confederacy was largely sustained by imports underscores the blockade's limited effectiveness.

This thesis presents an experimental study of the thermoelectrical properties of semiconductor quantum dots (QD). The measurements give information about the interplay between first order tunneling and macroscopic quantum tunneling transport effects in the presence of thermal gradients by the direct comparison of the thermoelectric response and the energy spectrum of the QD. The aim of the thesis is to contribute to the understanding of the charge and spin transport in few-electron quantum dots with respect to potential applications in future quantum computing devices. It also gives new insight into the field of low temperature thermoelectricity. The investigated QDs were defined electrostatically in a two dimensional electron gas (2DEG) formed with a GaAs/(Al,Ga)As heterostructure by means of metallic gate electrodes on top of the heterostructure. Negative voltages with respect to the potential of the 2DEG applied to the gate electrodes were used to deplete the electron gas below them and to form an isolated island of electron gas in the 2DEG which contains a few ten electrons. This QD was electrically connected to the 2DEG via two tunneling barriers. A special electron heating technique was used to create a temperature difference between the two connecting reservoirs across the QD. The resulting thermoelectric voltage was used to study the charge and spin transport processes with respect to the discrete energy spectrum and the magnetic properties of the QD. Such a two dimensional island usually exhibits a discrete energy spectrum, which is comparable to that of atoms. At temperatures below a few degrees Kelvin, the electrostatic charging energy of the QDs exceeds the thermal activation energy of the electrons in the leads, and the transport of electrons through the QD is dominated by electron-electron interaction effects. The measurements clarify the overall line shape of thermopower oscillations and the observed fine structure as well as additional spin effects in the thermoelectrical transport. The observations demonstrate that it is possible to control and optimize the strength and direction of the electronic heat flow on the scale of a single impurity and create spin-correlated thermoelectric transport in nanostructures, where the experimenter has a close control of the exact transport conditions. The results support the assumption that the performance of thermoelectric devices can be enhanced by the adjustment of the QD energy levels and by exploiting the properties of the spin-correlated charge transport via localized, spin-degenerate impurity states. Within this context, spin entropy has been identified as a driving force for the thermoelectric transport in the spin-correlated transport regime in addition to the kinetic contributions. Fundamental considerations, which are based on simple model assumptions, suggest that spin entropy plays an important role in the presence of charge valence fluctuations in the QD. The presented model gives an adequate starting point for future quantitative analysis of the thermoelectricity in the spin-correlated transport regime. These future studies might cover the physics in the limit of single electron QDs or the physics of more complex structures such as QD molecules as well as QD chains. In particular, it should be noted that the experimental investigations of the thermopower of few-electron QDs address questions concerning the entropy transport and entropy production with respect to single-bit information processing operations. These questions are of fundamental physical interest due to their close connection to the problem of minimal energy requirements in communication, and thus ultimately to the so called "Maxwell's demon" with respect to the second law of thermodynamics. / Diese Dissertation präsentiert eine experimentelle Studie über die thermoelektrischen Eigenschaften von Halbleiterquantenpunkten. Das thermoelektrische Verhalten der Quantenpunkte wird unter besonderer Berücksichtigung ihrer jeweiligen Energiespektren und magnetischen bzw Spin-Eigenschaften diskutiert. Die durchgeführten Messungen geben Aufschluss über das Zusammenspiel von Einzelelektronentunnelprozessen erster und höherer Ordnung unter dem Einfluss thermischer Gradienten. Somit trägt diese Dissertation zum Verständnis des Ladungs- und Spintransports in potentiellen, zukünftigen Bausteinen für die Quanteninformationsverarbeitung bei und ermöglicht neue Einblicke in das Themengebiet der Thermoelektrizität bei sehr tiefen Temperaturen. Die untersuchten Quantenpunkte wurden in einem zweidimensionalen Elektronengas (2DEG) mittels nanostrukturierter, metallischer "gates" erzeugt, die auf der Oberfläche einer GaAs/AlGaAs Heterostrukturoberfläche aufgebracht wurden. Durch das Anlegen negativer Spannungen in Bezug auf das Potential des 2DEGs, wurde das Elektronengas unter den gates verdrängt, so dass eine isolierte Insel entstand, die bis zu ca. 30 Elektronen zählte. Zwei Tunnelbarrieren dienten als elektrische Verbindung dieses Quantenpunkts zu den Zuleitungen. Unter Verwendung einer speziellen Stromheizungstechnik wurde eine Temperaturdifferenz zwischen den zwei Zuleitungsreservoirs über dem Quantenpunkt erzeugt. Die Untersuchung von Ladungs- und Spintransportprozessen erfolgte über den direkten Vergleich der resultierenden thermoelektrischen Spannung mit den jeweiligen Energiespektren der Quantenpunkte. Im Allgemeinen weist eine solche zweidimensionale Insel ein diskretes Energiespektrum auf, das vergleichbar mit dem einzelner Atome ist. Unterhalb einer Temperatur von wenigen Grad Kelvin, ist die elektrostatische Aufladungsenergie des Quantenpunkts größer als die thermische Anregungsenergie der Elektronen in den Zuleitungen. Als Folge bestimmen Elektron-Elektron-Wechselwirkungseffekte den Transport von Elektronen durch den Quantenpunkt. Die durchgeführten Messungen erklären den Verlauf der Thermokraft als Funktion des Quantenpunktpotentials einschließlich der aufgeprägten Feinstruktur sowie zusätzliche thermoelektrische Effekte, die von den Spin-Eigenschaften des Quantenpunkts hervorgerufen werden. Die Beobachtungen beweisen, dass es möglich ist Stärke und Richtung des elektronischen Wärmeflusses auf der Größenskala einzelner Verunreinigungen zu kontrollieren und gegebenenfalls zu optimieren sowie Spin-korrelierten thermoelektrischen Transport in künstlich hergestellten Nanostrukturen zu verwirklichen, welche eine gezielte Kontrolle der Transportbedingungen erlauben. Die Ergebnisse untermauern die Annahmen einer möglichen Verbesserung der Effizienz thermoelektrisch aktiver Materialien durch die Anpassung der energetischen Lage entsprechender Quantenpunktzustände und durch die Ausnutzung der thermoelektrischen Effekte im Spin-korrelierten Ladungstransport durch energetisch entartete, lokalisierte Zustände. In diesem Rahmen wurde erläutert, dass Spinentropie neben den kinetischen Beiträgen eine weitere treibende Kraft des thermoelektrischen Transports durch Quantenpunkte darstellt. Grundlegende Überlegungen, die auf einfachen Modellannahmen beruhen, lassen erwarten, dass die Beiträge der Spinentropie zum thermoelektischen Transport bei vorhandenen Fluktuationen der Anzahl der Ladungen auf dem Quantenpunkt eine signifikante Rolle spielen. Das vorgestellte Modell bietet hierzu einen geeigneten Ausgangspunkt für weitere quantitative Analysen der Thermoelektrizität im Spin-korrelierten Transportregime. Insbesondere sei darauf hingewiesen, dass die experimentelle Untersuchung der Thermokraft von Quantenpunktstrukturen, wie sie hier verwendet wurden, den Entropietransport und die Entropieerzeugung in Bezug zu Ein-Bit-Rechenoperationen setzen. Fragestellungen dieser Art sind von fundamentalem physikalischen Interesse aufgrund ihrer engen Verknüpfung mit der Frage nach dem minimalen Energieaufwand, der eine Kommunikation ermöglicht. Dieses Problem wird häufig mittels des so genannten Maxwell'schen Dämon diskutiert und hinterfragt in ihrem Ursprung den zweiten Hauptsatz der Thermodynamik.

<p>The endothelium plays an important part in blood flow regulation by producing the vasodilatory substance nitric oxide (NO). Various studies have shown that commonly accepted risk factors for coronary heart disease, such as hypertension, diabetes, hypercholesterolemia, smoking and mental stress impair endothelium-derived vasodilation by the NO-pathway. This thesis focuses on the effects of mental stress on the endothelium. Furthermore, the effects of epinephrine (E) and norepinephrine (NE) and blockades of adrenergic receptors were studied in the forearm in young healthy subjects.</p><p>Different blockades were given locally in the forearm, not affecting general hemodynamics. β-adrenoceptor blockade impaired endothelium-dependent vasodilation (EDV), while α-adrenoceptor blockade and neurogenic blockade caused a general vasodilation which was not endothelium dependent. Neuropeptide Y did not seem to influence blood flow in the resting forearm.</p><p>A short period of mental stress induced by an arithmetic task, impaired EDV in the forearm. This negative effect could be blocked by β-adrenergic, but not α-adrenergic receptor blockade.</p><p>Local infusions of E and NE in the human forearm induced vasodilation and vasoconstriction, respectively. As both EDV and endothelium-independent vasodilation were affected by both E and NE, the two catecholamines did not seem to affect vascular tone by an endothelium-specific mechanism.</p><p>Both cold pressure stress and mental stress induced impairments in flow-mediated vasodilation (FMD) when normalised for the degree of hyperemic blood flow.</p><p>These findings give us new insights in how mental stress and sympathetic activation affects the endothelium and how the negative effects can be prevented.</p>

The endothelium plays an important part in blood flow regulation by producing the vasodilatory substance nitric oxide (NO). Various studies have shown that commonly accepted risk factors for coronary heart disease, such as hypertension, diabetes, hypercholesterolemia, smoking and mental stress impair endothelium-derived vasodilation by the NO-pathway. This thesis focuses on the effects of mental stress on the endothelium. Furthermore, the effects of epinephrine (E) and norepinephrine (NE) and blockades of adrenergic receptors were studied in the forearm in young healthy subjects. Different blockades were given locally in the forearm, not affecting general hemodynamics. β-adrenoceptor blockade impaired endothelium-dependent vasodilation (EDV), while α-adrenoceptor blockade and neurogenic blockade caused a general vasodilation which was not endothelium dependent. Neuropeptide Y did not seem to influence blood flow in the resting forearm. A short period of mental stress induced by an arithmetic task, impaired EDV in the forearm. This negative effect could be blocked by β-adrenergic, but not α-adrenergic receptor blockade. Local infusions of E and NE in the human forearm induced vasodilation and vasoconstriction, respectively. As both EDV and endothelium-independent vasodilation were affected by both E and NE, the two catecholamines did not seem to affect vascular tone by an endothelium-specific mechanism. Both cold pressure stress and mental stress induced impairments in flow-mediated vasodilation (FMD) when normalised for the degree of hyperemic blood flow. These findings give us new insights in how mental stress and sympathetic activation affects the endothelium and how the negative effects can be prevented.

Was wäre, wenn es die Kontinentalsperre nicht gegeben hatte? Die Beantwortung dieser Frage setzt eine Beschäftigung mit den Konsequenzen der Blockade auf die wirtschaftliche Entwicklung der betroffenen Länder voraus. Desweiteren ist die Suche nach einem möglichen Alternativszenario notwendig, um einen Vergleich zwischen realem und kontrafaktischem Verlauf ziehen zu können. Diese Arbeit betrachtet zunächst die unterschiedliche Entwicklung der Textilindustrien in England und dem deutschsprachigen Raum. Die Auseinandersetzung mit dem Zustand vor, während und nach der Blockade leitet in die kontrafaktischen Überlegungen über. Hierbei wird ein Vorschlag entwickelt, wie ein solches kontingentes Alternativszenario aussehen könnte. Die in dieser Arbeit angestellten Überlegungen sollen einen Beitrag dazu leisten, die Bedeutung der Kontinentalsperre für die europaische Wirtschaftsgeschichte einschätzen zu können ...

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Central mechanisms involving aldosterone - mineralocorticoid receptor (MR) activation mediate the increase in sympathetic tone after myocardial infarction (MI). We hypothesized that an increase in cardiac sympathetic activity (CSA) post MI facilitates cardiac sympathetic axonal sprouting, and that central MR blockade attenuates CSA and reduces cardiac sympathetic hyperinnervation post MI. Western blotting and qRT-PCR were used to assess protein and gene expression, and fluorescent immunohistochemistry was used to study changes in sympathetic innervation. Tyrosine hydroxylase (TH) and Norepinephrine transporter protein content in the non-infarcted base of the heart remained unaltered. In contrast, protein gene product (PGP 9.5) protein was significantly increased 2 fold in the base of the heart, and 6 fold in the peri-infarct area at 1 wk post MI, and associated with increased ubiquitin expression. Cardiac myocytes rather than sympathetic axons were identified as the main source of elevated PGP 9.5 expression. At the infarct border sympathetic hyperinnervation was observed with a 4 fold increase in growth associated protein 43 (GAP 43), a 2 fold increase in TH and a 50% increase in PGP 9.5 positive fibers when compared to the epicardial side of the left ventricle in sham rats. Central infusion of the MR blocker eplerenone at 5 ug/day for 9 days post MI markedly attenuated the increase in TH, GAP 43 and PGP 9.5 nerve densities at the infarct border. Central MR blockade may attenuate sympathetic hyperinnervation by several mechanisms, including decreasing CSA post MI, or affecting expression or function of nerve growth factor protein. Marked PGP 9.5 expression occurs in cardiomyocytes early post MI, which may contribute to the increase in ubiquitin and the early cardiac remodeling post MI.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2002. / Härtill 5 uppsatser.